Document ID: EPA-R09-OAR-2020-0425-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: California; Sacramento Metro Area; 2008 8-Hour Ozone Nonattainment Area Requirements
Posted Date: 2020-10-29T04:00Z

[Federal Register Volume 85, Number 210 (Thursday, October 29, 2020)]
[Proposed Rules]
[Pages 68509-68533]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-23032]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2020-0425; FRL-10015-07-Region 9]

Approval of Air Quality Implementation Plans; California; 
Sacramento Metro Area; 2008 8-Hour Ozone Nonattainment Area 
Requirements

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve, or conditionally approve, all or portions of two state 
implementation plan (SIP) revisions submitted by California to meet 
Clean Air Act (CAA or ``Act'') requirements for the 2008 8-hour ozone 
national ambient air quality standards (NAAQS or ``standards'') in the 
Sacramento Metro ozone nonattainment area. These SIP revisions include 
the ``Sacramento Regional 2008 NAAQS 8-hour Attainment and Reasonable 
Further Progress Plan'' and the Sacramento Metro portion of the ``2018 
Updates to the California State Implementation Plan.'' Collectively, 
the EPA refers to these submittals as the ``Sacramento Metro Area Ozone 
SIP.'' The Sacramento Metro Area Ozone SIP addresses the CAA 
nonattainment area requirements for the 2008 ozone NAAQS, such as the 
requirements for an emissions inventory, an attainment demonstration, 
reasonable further progress, reasonably available control measures, and 
contingency measures, and it establishes motor vehicle emissions 
budgets. The EPA is proposing to approve the Sacramento Metro Area 
Ozone SIP as meeting all the applicable ozone nonattainment area 
requirements, except for the contingency measure requirement where the 
EPA is proposing a conditional approval. Also, the EPA is beginning the 
adequacy process for the 2023 and 2024 motor vehicle emissions budgets 
in the Sacramento Metro Area Ozone SIP via this proposed rule.

DATES: Written comments must arrive on or before November 30, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2020-0425 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, or if you need assistance in a language 
other than English or if you are a person with disabilities who needs a 
reasonable accommodation at no cost to you, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For 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.

FOR FURTHER INFORMATION CONTACT: Jerry Wamsley, Air Planning Office 
(ARD-2), EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105, 
(415) 947-4111, or by email at Wamsley.Jerry@epa.gov.

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

Table of Contents

I. Regulatory Context
    A. Ozone Standards, Area Designations, and SIPs
    B. The Sacramento Metro Ozone Nonattainment Area
    C. CAA and Regulatory Requirements for 2008 Ozone Nonattainment 
Area SIPs
II. Submissions from the State of California To Address 2008 Ozone 
Standard Requirements in the Sacramento Metro Area
    A. Summary of State Submissions
    B. Clean Air Act Procedural Requirements for Adoption and 
Submission of SIP Revisions
III. Evaluation of the Sacramento Metro Area Ozone SIP
    A. Emissions Inventories
    B. Emissions Statement
    C. Reasonably Available Control Measures Demonstration
    D. Attainment Demonstration
    E. Rate of Progress Plan and Reasonable Further Progress 
Demonstration
    F. Transportation Control Strategies and Measures to Offset 
Emissions Increases From Vehicle Miles Traveled
    G. Contingency Measures
    H. Motor Vehicle Emissions Budgets for Transportation Conformity
    I. Other Clean Air Act Requirements Applicable to Severe Ozone 
Nonattainment Areas

[[Page 68510]]

IV. Proposed Action
V. Statutory and Executive Order Reviews

I. Regulatory Context

A. Ozone Standards, Area Designations, and SIPs

    Ground-level ozone pollution is formed from the reaction of 
volatile organic compounds (VOC) and oxides of nitrogen 
(NOX) in the presence of sunlight.\1\ These two pollutants, 
referred to as ozone precursors, are emitted by many types of sources, 
including on-and off-road motor vehicles and engines, power plants and 
industrial facilities, and smaller area sources such as lawn and garden 
equipment and paints. Scientific evidence indicates that adverse public 
health effects occur following exposure to ozone, particularly in 
children and adults with lung disease. Breathing air containing ozone 
can reduce lung function and inflame airways, which can increase 
respiratory symptoms and aggravate asthma or other lung diseases.\2\
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    \1\ The State of California refers to reactive organic gases 
(ROG) rather than VOC in some of its ozone-related SIP submissions. 
As a practical matter, ROG and VOC refer to the same set of chemical 
constituents, and for the sake of simplicity, we refer to this set 
of gases as VOC in this proposed rule.
    \2\ ``Fact Sheet--2008 Final Revisions to the National Ambient 
Air Quality Standards for Ozone'' dated March 2008.
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    In 1979, under section 109 of the CAA, the EPA established primary 
and secondary national ambient air quality standards for ozone at 0.12 
parts per million (ppm) averaged over a 1-hour period (``1-hour ozone 
standard'').\3\
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    \3\ 44 FR 8202 (February 8, 1979).
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    With the CAA Amendments of 1990, the Sacramento Metro ozone 
nonattainment area (``Sacramento Metro Area'') was designated as 
``Serious'' for the 1979 1-hour ozone standard and was required to 
submit an attainment plan designed to meet this NAAQS by 1999. The 
California Air Resources Board (CARB) submitted such an attainment plan 
to the EPA on November 15, 1994, and we approved this attainment plan 
on January 8, 1997.\4\ When subsequent air quality modeling studies 
from the State showed that the control strategy in the 1994 attainment 
plan would not meet the 1-hour ozone standard, the State requested and 
the EPA approved a voluntary reclassification from Serious to ``Severe-
15.'' \5\ This reclassification extended the deadline for attaining the 
1-hour ozone standard from 1999 to November 2005. Based on the air 
quality data collected from 2007 through 2009, the EPA determined that 
the Sacramento Metro Area met the 1979 1-hour ozone standard on October 
18, 2012.\6\
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    \4\ 62 FR 1150 (January 8, 1997).
    \5\ 60 FR 20237 (April 25, 1995).
    \6\ 77 FR 64036 (October 18, 2012).
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    On July 18, 1997, the EPA revised the primary and secondary NAAQS 
for ozone to set the acceptable level of ozone in the ambient air at 
0.08 ppm, averaged over an 8-hour period (``1997 8-hour ozone 
standard'').\7\ The EPA set the 1997 8-hour ozone standard based on 
scientific evidence demonstrating that ozone causes adverse health 
effects at lower concentrations and over longer periods of time than 
was understood when the previous 1-hour ozone standard was set. The EPA 
determined that the 1997 8-hour standard would be more protective of 
human health, especially children and adults who are active outdoors, 
and individuals with a pre-existing respiratory disease, such as 
asthma.
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    \7\ 62 FR 38856 (July 18, 1997).
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    In 2004, the Sacramento Metro Area was designated as nonattainment 
for the 1997 8-hour ozone standard and classified as Serious.\8\ 
Subsequently, CARB requested that the EPA reclassify the Sacramento 
Metro Area, under CAA section 181(b)(3), from Serious to ``Severe-15.'' 
\9\ The EPA then finalized the reclassification of the Sacramento Metro 
Area to Severe-15 on May 5, 2010.\10\ The State and local air districts 
developed an attainment plan, along with state-wide and local control 
measures, for the 1997 8-hour ozone standard and submitted the plan and 
related components to the EPA over the course of several years from 
2006 to 2013.\11\ The EPA approved the ``Sacramento 8-Hour Ozone 
Attainment Plan'' on January 29, 2015.\12\
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    \8\ 69 FR 23858 (April 30, 2004).
    \9\ Letter dated February 14, 2008, from James N. Goldstene, 
Executive Officer, CARB, to Wayne Nastri, Regional Administrator, 
EPA Region IX.
    \10\ 75 FR 24409 (May 5, 2010).
    \11\ See Table 4 of our proposed rule for a listing of state and 
local submittals composing the attainment plan for the 1997 8-hour 
ozone standard; 79 FR 61803 (October 15, 2014).
    \12\ 80 FR 4795 (January 29, 2015). Please see our proposed rule 
for this final action for a complete description of the attainment 
plan and state and local control measures; 79 FR 61799 (October 15, 
2014).
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    On March 27, 2008, the EPA revised and further strengthened the 
primary and secondary NAAQS for ozone by setting the acceptable level 
of ozone in the ambient air at 0.075 ppm, averaged over an 8-hour 
period (``2008 8-hour ozone standard'').\13\ On May 21, 2012, we 
designated nonattainment areas for the 2008 8-hour ozone NAAQS.\14\ At 
the same time, we assigned classifications to many of these areas based 
upon their ozone design value, in accordance with the structure of part 
D, subpart 2 of Title I of the CAA.\15\ We designated the Sacramento 
Metro Area as nonattainment for the 2008 ozone standards, and at the 
request of CARB retained the Severe-15 classification, consistent with 
previous ozone NAAQS.\16\ The Sacramento Metro Area's outermost 
attainment date for the 2008 8-hour ozone standard is as expeditious as 
practicable but no later than July 20, 2027. As a practical matter, the 
Sacramento Metro Area would be required to demonstrate attainment of 
the 2008 NAAQS no later than the previous ozone season, 2026. As 
discussed further below, the EPA has determined that expeditious 
attainment for the Sacramento Metro Area can be achieved in 2024. 
Accordingly, the effective attainment date for the area is December 31, 
2024.
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    \13\ 73 FR 16436 (March 27, 2008).
    \14\ 77 FR 30088 (May 21, 2012) and 40 CFR 81.330.
    \15\ 69 FR 23858 (April 30, 2004) and 40 CFR 51.903(a). The 
designations and classifications for the 2008 8-hour ozone standard 
for California nonattainment areas are codified at 40 CFR 81.305. A 
design value is an ambient concentration calculated using a specific 
methodology to evaluate monitored air quality data and is used to 
determine whether an area's air quality is meeting a NAAQS. The 
methodology for calculating design values for the 8-hour ozone NAAQS 
is found in 40 CFR part 50, Appendix I.
    \16\ 77 FR 30088 (May 21, 2012).
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B. The Sacramento Metro Ozone Nonattainment Area

    The Sacramento Metro Area consists of Sacramento and Yolo counties 
and portions of El Dorado, Placer, Solano and Sutter counties.\17\ 
Several local air agencies have jurisdiction in this area. Sacramento 
County is under the jurisdiction of the Sacramento Metropolitan Air 
Quality Management District (SMAQMD). Yolo County and the eastern 
portion of Solano County comprise the Yolo-Solano AQMD (YSAQMD). The 
southern portion of Sutter County is part of the Feather River AQMD 
(FRAQMD). The western portion of Placer County is part of the Placer 
County Air Pollution Control District (PCAPCD). Lastly, the western 
portion of El Dorado County is part of the El Dorado County AQMD 
(EDCAQMD). In this action, we refer to these five districts 
collectively as the ``Districts.'' Under California law, each air 
district is responsible for adopting and implementing stationary source 
rules, while CARB adopts and

[[Page 68511]]

implements consumer products and mobile source rules. The Districts' 
and State's rules are submitted to the EPA by CARB.
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    \17\ For a precise description of the geographic boundaries of 
the Sacramento Metro Area for the 2008 ozone standards, see 40 CFR 
81.305. Specifically included portions are the eastern portion of 
Solano County, the western portions of Placer and El Dorado counties 
outside of the Lake Tahoe Basin, and the southern portion of Sutter 
County.
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    Current ambient 8-hour ozone levels in the Sacramento Metro Area 
are well above the 2008 8-hour ozone NAAQS. For the 2014-2016 period, 
the design value for the area, based on monitored readings at the 
Placerville monitor in El Dorado County, is 0.085 ppm. Since 2010, the 
highest design values have been found at the Folsom monitor in 
Sacramento County and the Placerville monitor in El Dorado County, 
ranging from 0.085 ppm to 0.102 ppm.\18\
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    \18\ Sacramento Regional 2008 NAAQS 8-hour Attainment and 
Reasonable Further Progress Plan, Table 4-2.
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C. CAA and Regulatory Requirements for 2008 Ozone Nonattainment Area 
SIPs

    States must implement the 2008 ozone NAAQS under Title 1, part D of 
the CAA, including sections 171-179B of subpart 1 (``Nonattainment 
Areas in General'') and sections 181-185 of subpart 2 (``Additional 
Provisions for Ozone Nonattainment Areas''). To assist states in 
developing effective plans to address ozone nonattainment problems, in 
2015, the EPA issued a SIP Requirements Rule (SRR) for the 2008 ozone 
NAAQS (``2008 Ozone SRR'') that addressed implementation of the 2008 
standards, including attainment dates, requirements for emissions 
inventories, attainment and reasonable further progress (RFP) 
demonstrations, among other SIP elements, as well as the transition 
from the 1997 ozone NAAQS to the 2008 ozone NAAQS and associated anti-
backsliding requirements.\19\ The 2008 Ozone SRR is codified at 40 CFR 
part 51, subpart AA. In section III below, we discuss in more detail 
the CAA and regulatory requirements for the air quality plans required 
to meet the 2008 ozone standard.
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    \19\ 80 FR 12264 (March 6, 2015).
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    The EPA's 2008 Ozone SRR was challenged, and on February 16, 2018, 
the U.S. Court of Appeals for the D.C. Circuit (``D.C. Circuit'') 
published its decision in South Coast Air Quality Management District 
v. EPA (``South Coast II'') \20\ vacating portions of the 2008 Ozone 
SRR. The only aspect of the South Coast II decision that affects this 
proposed action is the vacatur of the alternative baseline year for RFP 
plans. More specifically, the 2008 Ozone SRR required states to develop 
the baseline emissions inventory for RFP plans using the emissions for 
the most recent calendar year for which states submit a triennial 
inventory to the EPA under subpart A (``Air Emissions Reporting 
Requirements'') of 40 CFR part 51, which was 2011. The 2008 Ozone SRR, 
however, allowed states to use an alternative year, between 2008 and 
2012, for the baseline emissions inventory provided that the state 
demonstrated why the alternative baseline year was appropriate. In the 
South Coast II decision, the D.C. Circuit vacated the provisions of the 
2008 Ozone SRR that allowed states to use an alternative baseline year 
for demonstrating RFP.
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    \20\ South Coast Air Quality Management District v. EPA, 882 
F.3d 1138 (D.C. Cir. 2018). The term ``South Coast II'' is used in 
reference to the 2018 court decision to distinguish it from a 
decision published in 2006 also referred to as ``South Coast.'' The 
earlier decision involved a challenge to the EPA's Phase 1 
implementation rule for the 1997 ozone NAAQS. South Coast Air 
Quality Management Dist. v. EPA, 472 F.3d 882 (D.C. Cir. 2006).
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II. Submissions From the State of California To Address 2008 Ozone 
Standard Requirements in the Sacramento Metro Area

A. Summary of Submissions

    The EPA's designation of an area as nonattainment for a NAAQS 
starts the process for a state to develop and submit to the EPA a plan 
providing for attainment of the given NAAQS under title 1, part D of 
the CAA. For 8-hour ozone areas designated as nonattainment under the 
2008 ozone NAAQS, effective July 20, 2012, the Sacramento Metro Area's 
attainment plan was due by July 20, 2016.\21\ The State did not meet 
this July 20, 2016 deadline to submit an attainment plan and the EPA 
issued a finding of failure to submit an attainment SIP and several of 
its required elements on September 26, 2017.\22\ This finding of 
failure to submit an attainment plan and other required elements was 
addressed by the submittals discussed below.
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    \21\ 40 CFR 51.1108(b) and 40 CFR 51.1110.
    \22\ 82 FR 44736 (September 26, 2017), effective on October 26, 
2017.
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    California has submitted two SIP revisions to address the 
Sacramento Metro Area's CAA planning obligations for attaining the 2008 
8-hour ozone standard. The principal submittals are as follows:
     ``Sacramento Regional 2008 NAAQS 8-Hour Ozone Attainment 
Plan and Reasonable Further Progress Plan,'' dated July 25, 2017 
(``2017 Sacramento Regional Ozone Plan'' or ``Plan''); and
     The Sacramento Metro portion of CARB's ``2018 Updates to 
the California State Implementation Plan'' (``2018 SIP Update'').
    In this document, we are proposing action on all or portions of 
these SIP revisions, which are summarized below. Collectively, we refer 
to the relevant portions of these SIP revisions as the ``Sacramento 
Metro Area Ozone SIP.''
1. 2017 Sacramento Regional Ozone Plan
    On December 18, 2017, CARB submitted the 2017 Sacramento Regional 
Ozone Plan to the EPA as a revision to the California SIP.\23\ The 2017 
Sacramento Regional Ozone Plan addresses the nonattainment area 
requirements for the Sacramento Metro Area concerning the 2008 ozone 
NAAQS. The SIP revision for the 2017 Sacramento Regional Ozone Plan 
includes the Plan itself with its chapters and appendices, plus the 
Districts' resolutions of adoption for the plan, and CARB's resolution 
of adoption for the 2017 Sacramento Regional Ozone Plan. The 2017 
Sacramento Regional Ozone Plan was adopted by the Districts' governing 
boards beginning in late August through October 2017, and then by CARB, 
via Resolution 17-40, on November 16, 2017. See Table 1 for the 
Districts' adoption dates and board resolution or order numbers.
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    \23\ Letter dated December 18, 2017, from Richard Corey, 
Executive Officer, CARB, to Alexis Strauss, Acting Regional 
Administrator, EPA Region IX.

Table 1--Districts and Adoption Dates for 2017 Sacramento Regional Ozone
                                  Plan
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                                                                Board
           District             Hearing and  adoption dates  resolution/
                                                                 order
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SMAQMD.......................  August 24, 2017.............     2017-015
EDCAQMD......................  September 12, 2017..........     141-2017
FRAQMD.......................  October 2, 2017.............      2017-10
YSAQMD.......................  October 11, 2017............        17-06
PCAPCD.......................  October 12, 2017............        17-08
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    The 2017 Sacramento Regional Ozone Plan is organized into thirteen 
chapters and six technical appendices addressing the CAA requirements 
for VOC and NOX emissions inventories, air quality and 
photochemical modeling to demonstrate attainment of the 2008 ozone 
standard, reasonably available control measures (RACM) for each of the 
Districts along with the overall control strategy for the Sacramento 
Metro Area, RFP, adoption and implementation of transportation control 
strategies and measures, and contingency measures for failure to meet 
RFP or attain, among other requirements. Submittal of the 2017 
Sacramento Regional Ozone Plan and the EPA's completeness determination 
for the Plan set aside our September 26,

[[Page 68512]]

2017 finding of failure to submit.\24\ In addition to the 2017 
Sacramento Regional Ozone Plan, CARB submitted its Staff Report 
reviewing the plan and discussing the photochemical modeling supporting 
its attainment demonstration and referred to herein as the ``CARB Staff 
Report.'' \25\
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    \24\ Letter dated June 14, 2018, from Elizabeth Adams, Acting 
Director, Air Division, EPA Region IX, to Richard Corey, Executive 
Officer, CARB.
    \25\ ``Staff Report, ARB Review of the Sacramento Regional 2008 
NAAQS 8-Hour Ozone Attainment and Reasonable Further Progress Plan'' 
(``CARB Staff Report''), release date October 13, 2017.
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2. 2018 SIP Update
    On December 5, 2018, CARB submitted the 2018 SIP Update to the EPA 
as a revision to the California SIP.\26\ CARB developed the 2018 SIP 
Update in response to the court's decision in South Coast II vacating 
the 2008 Ozone SRR with respect to the use of an alternate baseline 
year for demonstrating RFP and to address contingency measure 
requirements in the wake of the court decision in Bahr v. EPA.\27\ The 
2018 SIP Update includes an RFP demonstration using the required 2011 
baseline year for the Sacramento Metro Area for the 2008 ozone NAAQS. 
The 2018 SIP Update also includes updated motor vehicle emission 
budgets and information to support the contingency measure element of 
the 2017 Sacramento Regional Ozone Plan. The 2018 SIP Update includes 
updates for 8 different California ozone nonattainment areas. We have 
already acted to approve portions of the 2018 SIP Update related to 
other nonattainment areas.\28\ In this action, we are proposing action 
on the Sacramento Metropolitan Area portion of the 2018 SIP Update, 
specifically, Section V--SIP Elements for the Sacramento Metropolitan 
Area.
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    \26\ Letter dated December 5, 2018, from Richard Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX. CARB adopted the 2018 SIP Update on October 25, 2018.
    \27\ Bahr v. EPA, 836 F.3d 1218 (9th Cir. 2016) (``Bahr v. 
EPA''). In Bahr v. EPA, the court rejected the EPA's longstanding 
interpretation of CAA section 172(c)(9) as allowing for early 
implementation of contingency measures. The court concluded that a 
contingency measure must take effect at the time the area fails to 
make RFP or attain by the applicable attainment date, not before.
    \28\ See, e.g., 84 FR 11198 (March 25, 2019) (final approval of 
the San Joaquin Valley portion of the 2018 SIP Update), 84 FR 52005 
(October 1, 2019) (final approval of the South Coast portion of the 
2018 SIP Update), and 85 FR 38081 (June 25, 2020) (final approval of 
the Ventura County portion of the 2018 SIP Update).
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    To supplement the contingency measure element of the 2017 
Sacramento Regional Ozone Plan, in a letter dated July 7, 2020, CARB 
forwarded to the EPA a May 26, 2020 letter of commitment from the 
Districts.\29\ In this letter, the Districts commit to modify their 
existing architectural coatings rules, and the SMAQMD also commits to 
adopt a VOC rule that would serve as contingency measures that will be 
triggered if the area fails to meet an RFP milestone or fails to attain 
the 2008 ozone NAAQS.\30\ In the July 7, 2020 letter, CARB commits to 
submit the Districts' revised rules to the EPA as a SIP revision within 
12 months of the EPA's final conditional approval of the contingency 
measures element of the Sacramento Metro Area Ozone SIP.\31\
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    \29\ Letter dated July 7, 2020, from Richard Corey, Executive 
Officer, CARB, to John Busterud, Regional Administrator, EPA Region 
IX.
    \30\ Letter dated May 26, 2020, from the Districts' respective 
Executive Officer or Air Pollution Control Officer, Alberto Ayala-
SMAQMD, Dave Johnston-EDCAQMD, Christopher Brown-FRAQMD, Erik White-
PCAPCD, Mat Ehrhardt-YSAQMD to Richard Corey, Executive Officer, 
CARB.
    \31\ Letter dated July 7, 2020, from Richard Corey, Executive 
Officer, CARB, to John Busterud, Regional Administrator, EPA Region 
IX.
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B. Clean Air Act Procedural Requirements for Adoption and Submission of 
SIP Revisions

    CAA sections 110(a) and 110(l) require a state to provide 
reasonable public notice and opportunity for public hearing prior to 
the adoption and submission of a SIP or SIP revision. To meet this 
requirement, every SIP submittal should include evidence that adequate 
public notice was given and an opportunity for a public hearing was 
provided consistent with the EPA's implementing regulations in 40 CFR 
51.102.
    The Districts, collectively, and CARB have satisfied the applicable 
statutory and regulatory requirements for reasonable public notice and 
hearing prior to the adoption and submittal of the SIP revisions that 
comprise the Sacramento Metro Area Ozone SIP. With respect to the 2017 
Sacramento Regional Ozone Plan, the Districts held hearings prior to 
adoption to discuss the plan and solicit public input. Prior to these 
adoption hearings, the Districts published notices of public hearing 
for the adoption of the 2017 Sacramento Regional Ozone Plan in local 
newspapers within the Districts.\32\ As noted in Table 1 above, the 
Districts adopted the 2017 Sacramento Regional Ozone Plan and each 
directed their respective Executive Officer or Air Pollution Control 
Officer to forward the plan to CARB for inclusion in the California 
SIP.
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    \32\ Please refer to the EPA's Completeness Determination and 
supporting information included in the docket for this proposal 
concerning the specific notices of public hearing, their evidence of 
publication in local newspapers, and the Districts' public hearings.
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    CARB also provided public notice and opportunity for public comment 
on the 2017 Sacramento Regional Ozone Plan. On October 12, 2017, CARB 
released for public review its Staff Report for the 2017 Sacramento 
Regional Ozone Plan and published a notice of public meeting to be held 
on November 16, 2017, to consider adoption of the 2017 Sacramento 
Regional Ozone Plan.\33\ On November 16, 2017, CARB held the public 
hearing and adopted the 2017 Sacramento Regional Ozone Plan as a 
revision to the California SIP, and directed the Executive Officer to 
submit the 2017 Sacramento Regional Ozone Plan to the EPA for approval 
into the California SIP.\34\ On December 18, 2017, the Executive 
Officer of CARB submitted the 2017 Sacramento Regional Ozone Plan to 
the EPA and included the transcript of the hearing held on November 16, 
2017.\35\ On June 14, 2018, the EPA determined that this submittal 
addressing the 2008 ozone NAAQS was complete.\36\
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    \33\ ``Notice of Public Meeting to Consider the Ozone State 
Implementation Plan for the Sacramento Nonattainment Region,'' 
signed by Richard W. Corey, CARB Executive Officer, October 12, 
2017. The Notice was made available on CARB's website.
    \34\ CARB Resolution 17-40.
    \35\ Compilation of Public Comments and Response for the 
November 16, 2017 Meeting of the State of California Air Resources 
Board.
    \36\ Letter dated June 14, 2018, from Elizabeth Adams, Acting 
Director, Air Division, EPA Region IX to Richard Corey, Executive 
Officer, CARB.
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    With respect to the 2018 SIP Update, CARB also provided public 
notice and opportunity for public comment. On September 21, 2018, CARB 
released for public review the 2018 SIP Update and published a notice 
of a public meeting to be held on October 23, 2018, to consider 
adoption of the 2018 SIP Update.\37\ On October 23, 2018, through 
Resolution 18-50, CARB adopted the 2018 SIP Update. On December 5, 
2018, CARB submitted the 2018 SIP Update to the EPA.
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    \37\ Notice of Public Meeting to Consider the 2018 Updates to 
the California State Implementation Plan signed by Richard Corey, 
Executive Officer, CARB, September 21, 2018.
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    Based on information provided in each of the SIP revisions 
summarized above, the EPA has determined that all hearings were 
properly noticed. Therefore, we find that the submittals of the 2017 
Sacramento Regional Ozone Plan and the 2018 SIP Update meet the 
procedural requirements for public notice and hearing in CAA sections 
110(a) and 110(l) and 40 CFR 51.102.

[[Page 68513]]

III. Evaluation of the Sacramento Metro Area Ozone SIP

A. Emissions Inventories

1. Statutory and Regulatory Requirements
    CAA sections 172(c)(3) and 182(a)(1) require states to submit for 
each ozone nonattainment area a ``base year inventory'' that is a 
comprehensive, accurate, current inventory of actual emissions from all 
sources of the relevant pollutant or pollutants in the area. In 
addition, the 2008 Ozone SRR requires that the inventory year be 
selected consistent with the baseline year for the RFP demonstration, 
which is the most recent calendar year for which a complete triennial 
inventory is required to be submitted to the EPA under the Air 
Emissions Reporting Requirements.\38\
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    \38\ 2008 Ozone SRR at 40 CFR 51.1115(a) and the Air Emissions 
Reporting Requirements at 40 CFR part 51 subpart A.
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    The EPA has issued guidance on the development of base year and 
future year emissions inventories for 8-hour ozone and other 
pollutants.\39\ Emissions inventories for ozone must include emissions 
of VOC and NOX and represent emissions for a typical ozone 
season weekday.\40\ States should include documentation explaining how 
the emissions data were calculated. When estimating mobile source 
emissions, states should use the latest emissions models and planning 
assumptions available at the time the SIP is developed.\41\
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    \39\ ``Emissions Inventory Guidance for Implementation of Ozone 
and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' EPA-454/B-17-002, May 2017. 
At the time the 2017 Sacramento Regional Ozone Plan was developed, 
the following EPA emissions inventory guidance applied: ``Emissions 
Inventory Guidance for Implementation of Ozone and Particulate 
Matter National Ambient Air Quality Standards (NAAQS) and Regional 
Haze Regulations'' EPA-454-R-05-001, August 2005.
    \40\ 40 CFR 51.1115(a) and (c), and 40 CFR 51.1100(bb) and (cc).
    \41\ 80 FR 12264, 12290 (March 6, 2015).
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    Future baseline emissions inventories must reflect the most recent 
population, employment, travel and congestion estimates for the area. 
In this context, ``baseline'' emissions inventories refer to emissions 
estimates for a given year and area that reflect rules and regulations 
and other measures that are already adopted. Future baseline emissions 
inventories are necessary to show the projected effectiveness of SIP 
control measures. Both the base year and future year inventories are 
necessary for photochemical modeling to demonstrate attainment.
2. Summary of State's Submission
    The 2017 Sacramento Regional Ozone Plan includes base year (2012) 
and future year baseline inventories for NOX and VOC for the 
Sacramento Metro Area. Documentation for the inventories is found in 
Chapter 5 (``Emissions Inventory'') and Appendix A (``Emission 
Inventory'') of the 2017 Sacramento Regional Ozone Plan.\42\ The 
emissions inventories represent average summer day emissions, 
consistent with the observation that ozone levels in the Sacramento 
Metro Area are typically higher from May through October.
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    \42\ Appendix A-4 contains detailed source category and 
emissions inventory projections from CARB's California Emission 
Projection Analysis Model. This detailed information is consolidated 
and presented in Chapter 5 of the plan.
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    The 2012 base year and future year inventories in the 2017 
Sacramento Regional Ozone Plan reflect District and CARB rules adopted 
prior to the plan in late 2015.\43\ The plan's emission reductions are 
based on continuing implementation of existing federal, state and local 
control measures. Both base year and projected future year inventories 
use the most recent EPA-approved version of California's mobile source 
emissions model at the time the plan was developed, EMFAC2014, for 
estimating on-road motor vehicle emissions.\44\
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    \43\ 2017 Sacramento Regional Ozone Plan, 5-11 and 7-12 to 7-14.
    \44\ 80 FR 77337 (December 14, 2015). EMFAC is short for 
EMission FACtor. The EPA announced the availability of the EMFAC2014 
model for use in state implementation plan development and 
transportation conformity in California on December 14, 2015. The 
EPA's approval of the EMFAC2014 emissions model for SIP and 
conformity purposes was effective on the date of publication of the 
notice in the Federal Register. EMFAC2014 was the most recently 
approved version of the EMFAC model that was available at the time 
of preparation of the 2017 Sacramento Regional Ozone Plan. Recently, 
the EPA approved an updated version of the EMFAC model, EMFAC2017, 
for future SIP development and transportation purposes in 
California; 84 FR 41717 (August 15, 2019).
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    VOC and NOX emissions estimates in the 2017 Sacramento 
Regional Ozone Plan are grouped into two general categories, stationary 
sources and mobile sources. Stationary sources are further divided into 
``point'' and ``area'' sources. Point sources typically refer to 
permitted facilities and have one or more identified and fixed pieces 
of equipment and emissions points. Area sources consist of widespread 
and numerous smaller emission sources, such as small permitted 
facilities and households. The mobile sources category is divided into 
two major subcategories, ``on-road'' and ``off-road'' mobile sources. 
On-road mobile sources include light-duty automobiles, light-, medium-, 
and heavy-duty trucks, and motorcycles. Off-road mobile sources include 
aircraft, locomotives, construction equipment, mobile equipment, and 
recreational vehicles.
    For the 2017 Sacramento Regional Ozone Plan, point source emissions 
for the 2012 base year emissions inventory are based on reported data 
from facilities using the Districts' annual emissions reporting 
programs. Area sources include smaller emissions sources distributed 
across the nonattainment area. CARB and the Districts estimate 
emissions for area sources using established inventory methods, 
including publicly available emission factors and activity information. 
Activity data are derived from national survey data such as the Energy 
Information Administration or from local sources such as public 
utilities, paint suppliers, and Districts' databases. Emission factors 
used for the estimates come from many sources, such as facility and 
equipment source tests, compliance reports, and the EPA's compilation 
of emissions factors document known as ``AP-42.''
    CARB calculated the on-road emissions inventories in the 2017 
Sacramento Regional Ozone Plan and the 2018 SIP Update using the 
EMFAC2014 model and the vehicle travel activity data provided by the 
Sacramento Council of Governments (SACOG) in its ``2016 Metropolitan 
Transportation Plan/Sustainable Communities Strategy'' (``2016 MTP/
SCS'') \45\ as updated in the ``2017-20 Metropolitan Transportation 
Improvement Program'' (``2017 MTIP'') \46\ and the Metropolitan 
Transportation Commission (MTC) in its 2012 ``Bay Area Plan--Preferred 
Land Use and Transportation and Investment Strategy.'' \47\ CARB 
provided emissions inventories for off-road equipment, including 
construction and mining equipment, industrial and commercial equipment, 
lawn and garden equipment, agricultural equipment, ocean-going

[[Page 68514]]

vessels, commercial harbor craft, locomotives, cargo handling 
equipment, pleasure craft, and recreational vehicles. CARB uses several 
models to estimate emissions for more than one hundred off-road 
equipment categories.\48\ Aircraft emissions are developed in 
conjunction with the airports in the region.
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    \45\ SACOG, ``2016 Metropolitan Transportation Plan/Sustainable 
Communities Strategy,'' February 2016. Available at http://www.sacog.org/general-information/2016-mtpscs.
    \46\ SACOG, ``2017-20 Metropolitan Transportation Improvement 
Program,'' September 15, 2016, Appendix A-6, ``Amendment #1 to the 
2016 Metropolitan Transportation Plan/Sustainable Communities 
Strategy,'' available at https://www.sacog.org/post/2017-20-mtip.
    \47\ 2017 Sacramento Regional Ozone Plan, Sections 10-2--10-6. 
2018 SIP Update, 31. SACOG is the regional transportation planning 
agency for the greater Sacramento area and covers Sacramento and 
Yolo counties, and portions of El Dorado, Placer, and Sutter 
counties. MTC is the regional transportation planning agency for the 
San Francisco Bay area, including portions of Solano County within 
the Sacramento Metro Area.
    \48\ 2017 Sacramento Regional Ozone Plan, 5-4.
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    Table 2 provides a summary of the Sacramento Metro Area's 2012 base 
year, interim, and future attainment year baseline emissions estimates 
in tons per average summer day for NOX and VOC. These 
inventories provide the basis for the control measure analysis and the 
attainment demonstrations in the 2017 Sacramento Regional Ozone Plan. 
This emissions inventory includes emissions throughout the Sacramento 
Metro Area. In the 2012 emissions inventory, stationary and area 
sources account for roughly 45 percent of VOC emissions and 10 percent 
of the NOX emissions in the Sacramento Metro Area while 
mobile sources account for roughly 55 percent of the VOC emissions and 
90 percent of the NOX emissions. For a more detailed 
discussion of the inventories, see Chapter 5 and Appendix A-4 of the 
2017 Sacramento Regional Ozone Plan.

                          Table 2--Sacramento Metro Area Base Year, Interim, and Attainment Year Baseline Emissions Inventories
                                                     [Summer planning inventory, tons per day (tpd)]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   2012                    2018                    2021                    2024
                     Source category                     -----------------------------------------------------------------------------------------------
                                                              NOX         VOC         NOX         VOC         NOX         VOC         NOX         VOC
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stationary Sources......................................           8          22           7          22           7          23           7          23
Area Sources............................................           3          29           2          29           2          30           2          31
On-Road Mobile Sources..................................          61          34          35          20          26          16          19          14
Off-Road Mobile Sources.................................          30          26          26          20          23          18          21          17
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................         101         110          69          91          58          87          49          84
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: 2017 Sacramento Regional Ozone Plan, Chapter 5, tables 5-1 and 5-2. The sum of the emissions values may not equal the total shown due to
  rounding of the numbers.

    Future emissions forecasts in the 2017 Sacramento Regional Ozone 
Plan, particularly on-road mobile source emissions, are based primarily 
on demographic and economic growth projections provided by SACOG, the 
metropolitan planning organization (MPO) for the Sacramento Metro Area, 
and the MTC, the MPO for Solano County. The Districts and CARB 
developed stationary and area source control factors in reference to 
the 2012 base year, and then used the California Emission Projection 
Analysis Model to project these 2012 baseline inventories to future 
years.\49\
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    \49\ 2017 Sacramento Regional Ozone Plan, Chapter 5, and 
Appendices A-2 and A-4.
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    Following the South Coast II decision, CARB submitted the 2018 SIP 
Update to the EPA to revise, among other things, the RFP demonstration 
in the 2017 Sacramento Regional Ozone Plan based on a 2011 RFP baseline 
year (i.e., rather than 2012).\50\ Our analysis of the emissions 
inventories for the 2011 RFP baseline year and RFP milestone years 2017 
and 2020 can be found in section III.E below.
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    \50\ 2018 SIP Update, Section V (``SIP Elements for the 
Sacramento Metropolitan Area''), 27-34; and Appendix A, A-15 through 
A-18.
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3. The EPA's Review of the State's Submission
    We have reviewed the 2012 base year emissions inventory in the 2017 
Sacramento Regional Ozone Plan, and the inventory methodologies used by 
the District and CARB, for consistency with CAA requirements and EPA 
guidance. First, as required by EPA regulation, we find that the 2012 
inventory includes estimates of VOC and NOX for a typical 
ozone season weekday and that CARB has provided adequate documentation 
explaining how the emissions are calculated. Second, we find that the 
2012 base year emissions inventory in the 2017 Sacramento Regional 
Ozone Plan reflects appropriate emissions models and methodologies; 
therefore, the submitted emissions inventory represents a 
comprehensive, accurate, and current inventory of actual emissions 
during that year in the Sacramento Metro Area. Third, we find that 
selection of year 2012 for the base year emissions inventory is 
appropriate because it is consistent with the 2011 RFP baseline year 
(from the 2018 SIP Update) that is derived from a common set of models 
and methods. Consequently, the EPA is proposing to approve the 2012 
emissions inventory in the 2017 Sacramento Regional Ozone Plan as 
meeting the requirements for a base year inventory set forth in CAA 
section 182(a)(1) and 40 CFR 51.1115.
    With respect to future year baseline projections, we have reviewed 
the growth and control factors and find them acceptable and conclude 
that the future baseline emissions projections in the 2017 Sacramento 
Regional Ozone Plan reflect appropriate calculation methods and the 
latest planning assumptions. Also, as a general matter, the EPA will 
approve a SIP revision that takes emissions reduction credit for a 
control measure only where the EPA has approved the measure as part of 
the SIP. Thus, to take credit for the emissions reductions from newly 
adopted or amended District rules for stationary sources, the related 
rules must be approved by the EPA into the SIP. The 2017 Sacramento 
Regional Ozone Plan emissions inventories reflect credit for local VOC 
and NOX control measures adopted and submitted to CARB 
through late 2015 and for the future effects of these currently adopted 
control measures; no new future local stationary or area source control 
measures were submitted or credited within the Plan. With respect to 
mobile sources, the EPA has acted in recent years to approve CARB 
mobile source regulations into the California SIP.\51\ CARB mobile 
source control measures are reviewed in more detail in Sections III.C 
and III.D of this action. Based on our review, we find that the future 
year baseline projections in the 2017 Sacramento Regional Ozone Plan 
are properly supported by SIP-approved stationary and mobile source 
measures.
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    \51\ 81 FR 39424 (June 16, 2016), 82 FR 14446 (March 21, 2017), 
and 83 FR 23232 (May 18, 2018).
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    In September 2019 and April 2020, the U.S. Department of 
Transportation and the EPA published separate final actions concerning 
the ``Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule'' (``SAFE 
rule'') that, among other things, withdrew the EPA's

[[Page 68515]]

2013 waiver of preemption for CARB's Zero Emissions Vehicle (ZEV) sales 
mandate and Greenhouse Gas (GHG) standards that are applicable to new 
model year 2021 through 2025 light-duty vehicles (``SAFE Part 1''), and 
relaxed federal GHG emissions and fuel economy standards (``SAFE Part 
2'').\52\ The future year emissions projections in the 2017 Sacramento 
Regional Ozone Plan assume implementation of CARB's entire Advanced 
Clean Cars (ACC) program including the third generation of Low-Emission 
Vehicle (``LEV III'') criteria pollutant standards, but also including 
the ZEV sales mandate and GHG standards. The Plan's on-road emissions 
projections for NOX and VOCs are based on EMFAC2014, the 
EPA-approved model at the time the Plan was developed, and assumptions 
concerning implementation of the ACC program. Calculations for other 
portions of the future year emissions inventories (e.g., the point and 
area source portions of the inventories) also include assumptions about 
the continued implementation of the ACC program, which were appropriate 
when the plan was submitted in 2017.
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    \52\ 84 FR 51310 (September 27, 2019) and 85 FR 24174 (April 30, 
2020).
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    In response to the EPA's final action on SAFE Part 1, CARB 
developed adjustment factors for EMFAC to account for criteria 
pollutant emissions increases associated with the revocation of the ZEV 
sales mandate waiver.\53\ CARB's EMFAC off-model adjustment factors are 
multipliers that are to be applied to gasoline-powered light-duty 
automobiles, light-duty trucks and medium-duty vehicles modeled by 
EMFAC2014 (and its more recent EPA-approved update, EMFAC2017). The EPA 
reviewed CARB's EMFAC off-model adjustment factors and concluded that 
they are acceptable for use because the effect of their application is 
more conservative than necessary, and that, therefore, the factors may 
be used in transportation conformity determinations and SIP 
development.\54\ We applied the adjustment factors to the relevant 
light duty gasoline motor vehicle source categories in the relevant 
years, 2023--RFP year and 2024--attainment year, to estimate the VOC 
and NOX increases in the Sacramento Metro Area relative to 
those included in the Plan and found that the emissions increases were 
so small as to be negligible.\55\
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    \53\ Letter dated March 5, 2020, from Steven S. Cliff, Deputy 
Executive Officer, CARB, to Elizabeth Adams, Director, Air and 
Radiation Division, EPA, Region IX; includes enclosure, ``EMFAC Off-
Model Adjustment Factors to Account for the SAFE Vehicles Rule Part 
One,'' November 20, 2019. CARB has determined that additional EMFAC 
adjustment factors for criteria pollutants are not needed in 
response to SAFE Part 2; CARB, ``EMFAC Off-Model Adjustment Factors 
for Carbon Dioxide (CO2) Emissions to Account for the 
SAFE Vehicles Rule Part One and the Final SAFE Rule,'' June 26, 
2020.
    \54\ Letter dated March 12, 2020, from Elizabeth J. Adams, 
Director, Air and Radiation Division, EPA Region IX, to Steven 
Cliff, Deputy Executive Officer, CARB.
    \55\ We estimated SAFE rule effects as follows: 2023 VOC and 
NOX emissions increase 0.0115 and 0.0026 tons per day, 
respectively; 2024 VOC and NOX emissions increase 0.0189 
and 0.0047 tons per day, respectively.
---------------------------------------------------------------------------

    SAFE Parts 1 and 2 could result in a higher level of gasoline 
production, transport, and usage, with associated upstream emissions, 
than had been assumed for the Plan. We believe, however, that the 
incremental increase in upstream impacts would be limited between now 
and 2024, the last year addressed in this Plan. Moreover, the relevant 
source categories that may be affected by increased gasoline 
production, transport, and usage: Oil and gas production (combustion), 
and petroleum production and marketing, collectively represent only 5.6 
percent of the area's projected VOC emissions estimates and 0.02 
percent of the area's projected NOX emissions estimates for 
the relevant years.\56\ As such, the anticipated small incremental 
increase in emissions from these upstream sources due to higher-than-
expected gasoline consumption in the wake of SAFE Part 1 and SAFE Part 
2 would be inconsequential from the standpoint of the RFP and 
attainment demonstrations in the Plan. Therefore, we find that the 
regulatory changes established by the SAFE Part 1 and Part 2 final 
rules do not undermine the RFP and attainment demonstrations in the 
Sacramento Metro Area Ozone SIP.
---------------------------------------------------------------------------

    \56\ Total petroleum production and marketing VOC and 
NOX emissions in the Sacramento Metro Area are estimated 
as follows: 4.72 tpd and 0.01 tpd in 2023, respectively; and, 4.62 
tpd and 0.01 tpd in 2024, respectively. Total VOC and NOX 
emissions in the Sacramento Metro Area are estimated as follows: 
83.46 and 48.25 in 2023, respectively; and, 82.86 and 46.53, 
respectively. 2018 SIP Update, A-15 to A-18.
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B. Emissions Statement

1. Statutory and Regulatory Requirements
    Section 182(a)(3)(B)(i) of the Act requires states to submit a SIP 
revision requiring owners or operators of stationary sources of VOC or 
NOX to provide the state with statements of actual emissions 
from such sources. Statements must be submitted at least every year and 
must contain a certification that the information contained in the 
statement is accurate to the best knowledge of the individual 
certifying the statement. Section 182(a)(3)(B)(ii) of the Act allows 
states to waive the emissions statement requirement for any class or 
category of stationary sources that emit less than 25 tons per year 
(tpy) of VOC or NOX, if the state provides an inventory of 
emissions from such class or category of sources as part of the base 
year or periodic inventories required under CAA sections 182(a)(1) and 
182(a)(3)(A), based on the use of emission factors established by the 
EPA or other methods acceptable to the EPA.
    The preamble of the 2008 Ozone SRR states that if an area has a 
previously approved emissions statement rule for the 1997 ozone NAAQS 
or the 1-hour ozone NAAQS that covers all portions of the nonattainment 
area for the 2008 ozone NAAQS, such rule should be sufficient for 
purposes of the emissions statement requirement for the 2008 ozone 
NAAQS.\57\ The state should review the existing rule to ensure it is 
adequate and, if so, may rely on it to meet the emissions statement 
requirement for the 2008 ozone NAAQS. Where an existing emissions 
statement requirement is still adequate to meet the requirements of 
this rule, states can provide the rationale for that determination to 
the EPA in a written statement in the SIP to meet this requirement. 
States should identify the various requirements and how each is met by 
the existing emissions statement program. Where an emissions statement 
requirement is modified for any reason, a state must provide the 
revision to the emissions statement as part of its SIP.
---------------------------------------------------------------------------

    \57\ 80 FR 12264, 12291 (March 6, 2015).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The Districts in the Sacramento Metro Area have adopted and CARB 
has submitted emissions statement rules for incorporation into the 
California SIP. The EPA has reviewed and approved into the SIP the 
rules listed in Table 3.

[[Page 68516]]

Table 3--EPA-Approved Emissions Statement Rules for the Sacramento Metro
                                  Area
------------------------------------------------------------------------
                                                      EPA approval date
          District              Rule No. and name         and cite
------------------------------------------------------------------------
SMAQMD......................  Rule 105, Emission    73 FR 32240, June 6,
                               Statements.           2008.
EDCAQMD.....................  Rule 1000, Emission   69 FR 29880, May 26,
                               Statement.            2004.
FRAQMD......................  Rule 4.8, Further     69 FR 29880, May 26,
                               Information.          2004.
YSAQMD......................  Rule 3.18, Emission   69 FR 29880, May 26,
                               Statements.           2004.
PCAPCD......................  Rule 503, Emission    77 FR 72968,
                               Statement.            December 7, 2012.
------------------------------------------------------------------------

    The CARB Staff Report submitted with the 2017 Sacramento Regional 
Ozone Plan certified the submittal and EPA approval of the Districts' 
emissions statement rules and their applicability to the area.\58\ CARB 
certified that these emissions statement rules are applicable to the 
area and the 75 ppb ozone standard because the nonattainment area 
boundaries have not changed since the EPA's approval of these rules and 
the reporting thresholds within the rules are appropriate.
---------------------------------------------------------------------------

    \58\ CARB Staff Report, 7. The CARB Staff Report cites a June 6, 
2006 rulemaking for SMAQMD Rule 105; while the Federal Register 
citation is correct, the correct date is June 6, 2008. The EPA's 
2012 approval of PCAPCD Rule 503 provided in Table 3 is not cited by 
CARB.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    As noted above, the EPA has reviewed and approved the Districts' 
emissions statement rules as meeting the requirements of section 
182(a)(3)(B) and incorporated them into the SIP. Also, although the 
emissions reporting requirements in these rules do not apply to 
permitted sources of emissions less than 10 or 25 tpy (depending on the 
subject rule), we note that such an exclusion is allowed under CAA 
section 182(a)(3)(B)(ii), so long as the state includes estimates of 
such class or category of stationary sources in base year emissions 
inventories and periodic inventories, submitted under CAA sections 
182(a)(1) and 182(a)(3)(A), based on EPA emission factors or other 
methods acceptable to the EPA. The EPA has routinely approved emissions 
inventories developed by the Districts and CARB for the Sacramento 
Metro Area that include actual emissions estimates for all stationary 
sources or classes or categories of such sources, including those 
emitting less than the reporting thresholds within these emissions 
statement rules, and that such inventories provide the basis for 
inventories submitted to meet the requirements of CAA sections 
182(a)(1) and 182(a)(3)(A). Most recently, we approved the base year 
emissions inventory for the 1997 8-hour ozone NAAQS on January 29, 
2015.\59\ Similarly, we are proposing approval of the base year 
inventory for the 2008 ozone NAAQS, as noted in the previous section. 
Therefore, for the reasons described above, we propose to approve the 
2017 Sacramento Regional Ozone Plan as meeting the emissions statement 
requirements under CAA section 182(a)(3)(B).
---------------------------------------------------------------------------

    \59\ 80 FR 4795.
---------------------------------------------------------------------------

C. Reasonably Available Control Measures Demonstration

1. Statutory and Regulatory Requirements
    CAA section 172(c)(1) requires that each attainment plan provide 
for the implementation of all RACM as expeditiously as practicable 
(including such reductions in emissions from existing sources in the 
area as may be obtained through implementation of reasonably available 
control technology (RACT)) and for attainment of the NAAQS. For each 
nonattainment area required to submit an attainment demonstration, the 
2008 Ozone SRR requires that the state concurrently submit a SIP 
revision showing that it has adopted all RACM necessary to demonstrate 
attainment as expeditiously as practicable and to meet any RFP 
requirements.\60\
---------------------------------------------------------------------------

    \60\ 40 CFR 51.1112(c).
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    The EPA has provided guidance interpreting the RACM requirement in 
the General Preamble for the Implementation of the Clean Air Act 
Amendments of 1990 (``General Preamble'') and in a memorandum entitled 
``Guidance on the Reasonably Available Control Measure Requirement and 
Attainment Demonstration Submissions for Ozone Nonattainment Areas.'' 
\61\ In short, to address the requirement to adopt all RACM, states 
should consider all potentially reasonable control measures for source 
categories in the nonattainment area to determine whether they are 
reasonably available for implementation in that area and whether they 
would, if implemented individually or collectively, advance the area's 
attainment date by one year or more.\62\ Any measures that are 
necessary to meet these requirements that are not either federally 
promulgated, or part of the state's SIP, must be submitted in 
enforceable form as part of the state's attainment plan for the area.
---------------------------------------------------------------------------

    \61\ General Preamble, 57 FR 13498, 13560 (April 16, 1992) and 
memorandum dated November 30, 1999, from John Seitz, Director, 
OAQPS, to Regional Air Directors, titled ``Guidance on the 
Reasonably Available Control Measure Requirement and Attainment 
Demonstration Submissions for Ozone Nonattainment Areas.''
    \62\ Id. 44 FR 20372 (April 4, 1979), and memorandum dated 
December 14, 2000, from John S. Seitz, Director, OAQPS, to Regional 
Air Directors, titled ``Additional Submission on RACM from States 
with Severe 1-hour Ozone Nonattainment Area SIPs.''
---------------------------------------------------------------------------

    For ozone nonattainment areas classified as ``Moderate'' or above, 
CAA section 182(b)(2) also requires implementation of RACT for all 
major sources of VOC and for each VOC source category for which the EPA 
has issued a control techniques guideline (CTG). CAA section 182(f) 
requires that RACT under section 182(b)(2) also apply to major 
stationary sources of NOX. In Severe-15 areas, a major 
source is a stationary source that emits or has the potential to emit 
at least 25 tpy of VOC or NOX (see CAA section 182(d) and 
(f)). CARB has submitted separate SIP revisions to address these 
requirements for each of the Districts.\63\ We are not addressing the 
section 182 RACT requirements in today's proposed rule.
---------------------------------------------------------------------------

    \63\ The EPA fully approved the submissions for EDCAQMD (83 FR 
67696, December 31, 2018), FRAQMD (80 FR 38959, July 18, 2015), and 
PCAPCD (82 FR 38604, August 15, 2017). The EPA has not yet acted on 
the SMAQMD and YSAQMD submissions.
---------------------------------------------------------------------------

2. Summary of the State's Submission
    For the 2017 Sacramento Regional Ozone Plan, the Districts, SACOG, 
and CARB undertook collective and individual processes to identify and 
evaluate potential RACM that could contribute to expeditious attainment 
of the 2008 ozone NAAQS in the Sacramento Metro Area. We describe each 
agency's evaluation below.
a. The Districts' RACM Analysis
    The Districts' RACM demonstration for the 2008 ozone NAAQS focuses 
on stationary and area source controls, and is described in Appendix E 
(``Reasonably Available Control

[[Page 68517]]

Measures (RACM) Analysis'') of the 2017 Sacramento Regional Ozone Plan. 
Appendix E contains summary analyses of all potential control measures 
for emissions reduction opportunities, as well as their economic and 
technological feasibility. As a first step in the RACM analysis, the 
Districts prepared a detailed inventory of emissions sources that emit 
VOC and NOX to identify source categories from which 
emissions reductions would effectively contribute to attainment. 
Details on the methodology and development of this source category and 
control measure review are discussed in chapter 7 and appendix E of the 
2017 Sacramento Regional Ozone Plan.\64\
---------------------------------------------------------------------------

    \64\ 2017 Sacramento Regional Ozone Plan, Appendix E provides 
the overall discussion, while tables E-1 through E-5 list the 
Districts' rules that were reviewed for RACM.
---------------------------------------------------------------------------

    The Districts' RACM analysis builds upon a foundation of the 
respective rules developed for earlier ozone plans and approved as part 
of the SIP, e.g., the Sacramento 8-Hour Ozone Attainment Plan for the 
1997 8-hour ozone standard. The Districts' rules listed in Tables E-1 
to E-5 of the 2017 Sacramento Regional Ozone Plan establish emissions 
limits or other types of emissions controls for a wide range of 
sources, including use of solvents, refineries, gasoline storage, 
architectural coatings, spray booths, various types of commercial 
coatings, boilers, steam generators and process heaters, oil and gas 
production wells, and many more. These rules have already provided 
significant and ongoing reductions toward attainment of the 2008 ozone 
NAAQS by 2024.
    To identify all potential RACM, staff from the Districts reviewed 
multiple sources of control measure information. These sources included 
past regional ozone plans, rules adopted between January 2006 and July 
2013 by other California air quality management districts, the EPA's 
``RACT/BACT/LAER Clearinghouse,'' \65\ CARB's BACT Clearinghouse, the 
Bay Area AQMD's 2010 Clean Air Plan, the South Coast AQMD's 2012 Air 
Quality Management Plan, and rules from ozone nonattainment areas in 
other states, such as Houston-Galveston-Brazoria (Texas), Dallas-Fort 
Worth (Texas), and Baltimore (Maryland). Next, the Districts performed 
the RACM analyses for the stationary and areawide sources within their 
jurisdictions. For each potential RACM measure, Districts' staff 
estimated the emissions inventory, emissions reductions, and cost 
effectiveness. With this process, the Districts evaluated and analyzed 
all reasonable control measures that were available to include within 
the 2017 Sacramento Regional Ozone Plan. The Districts determined that 
emissions reductions associated with the evaluated control measures 
would not advance the area's attainment date or RFP because the 
emission reductions, in total, were either too small or 
unquantifiable.\66\
---------------------------------------------------------------------------

    \65\ LAER means lowest achievable emission rate. For more 
information on the RACT/BACT/LAER Clearinghouse, see https://cfpub.epa.gov/RBLC/index.cfm?action=Home.Home⟨=en.
    \66\ 2017 Sacramento Regional Ozone Plan, Appendix E and Tables 
E-1 through Table E-5. These tables present a list of the individual 
district rules and control measures evaluated by the Districts and a 
brief discussion of their respective conclusions for each district 
rule or source category.
---------------------------------------------------------------------------

    As discussed above, the Districts are required to make submittals 
addressing the CAA section 182(b)(2) requirement to implement RACT for 
all major sources of VOC and for each VOC source category for which the 
EPA has issued control techniques guidelines. CAA section 182(f) 
requires that RACT under section 182(b)(2) also apply to major 
stationary sources of NOX. California has submitted the CAA 
section 182 RACT SIPs from the Districts, and the EPA has approved the 
submittals from EDCAQMD, FRAQMD, and PCAPCD. The CARB Staff Report, 
submitted with the 2017 Sacramento Regional Ozone Plan, identified 
commitments by SMAQMD and YSAQMD to submit or amend rules for several 
source categories to address the RACT SIP requirement.\67\ As a result, 
the SMAQMD and YSAQMD adopted or amended the following stationary 
source rules: SMAQMD Rule 419 (``Miscellaneous Combustion Units''); 
SMAQMD Rule 468 (``Plastic Parts''); and YSAQMD Rule 2.29 (``Graphic 
Arts''). Subsequently, the State submitted these rules to the EPA in 
2018 and 2019.\68\ Within the 2017 Sacramento Regional Ozone Plan, the 
SMAQMD and YSAQMD evaluated these rules and/or the relevant source 
categories for RACM and found that controls applied to these sources 
would not individually or collectively advance the attainment date.\69\ 
The control strategy for the Sacramento Metro Area Ozone SIP, overall, 
takes credit for emissions reductions from the Districts' stationary or 
area source rules adopted or amended before late 2015.\70\ 
Consequently, any emission reductions after 2015 and associated with 
the later 2018 amendments to or adoption of these SMAQMD and YSAQMD 
rules to meet the CAA section 182(b)(2) requirement are not credited or 
incorporated within the attainment demonstration of the Sacramento 
Metro Area Ozone SIP. Accordingly, the EPA's approval of these three 
rules, submitted in 2018 and 2019, are not required for our proposed 
action on the Sacramento Metro Area Ozone SIP; however, our review and 
approval into the SIP of these local rules remain relevant for our 
action on the submitted RACT SIPs, in accordance with CAA section 
182(b)(2).
---------------------------------------------------------------------------

    \67\ CARB Staff Report, 9.
    \68\ California submitted these rules to the EPA on the 
following dates: SMAQMD Rule 419 on August 15, 2018 and January 23, 
2019; SMAQMD Rule 468 on May 18, 2018; and YSAQMD Rule 2.29 on 
August 15, 2018.
    \69\ 2017 Sacramento Regional Ozone Plan, Appendix E.4, Table E-
1, and Appendix E.8, Table E-5.
    \70\ 2017 Sacramento Regional Ozone Plan, 5-11 and 7-12 to 7-14.
---------------------------------------------------------------------------

b. Local Jurisdictions' RACM Analysis and Transportation Control 
Measures
    The 2017 Sacramento Regional Ozone Plan's Appendix E-9 
(``Sacramento Area Council of Governments (SACOG) Transportation 
Control Measures Considered''), contains the transportation control 
measures (TCMs) RACM component for the plan. This analysis was 
conducted by SACOG, the MPO for the Sacramento Metro Area region. In 
its initial analysis, SACOG conducted a comprehensive review of 
implemented TCMs in California and other states, measures and 
strategies from the Sacramento Region's 2009 Ozone SIP, and statewide 
and mobile source emissions reduction strategies, and identified almost 
100 potential TCM measures. Of these, SACOG selected and analyzed 22 
measures that were not already implemented in Sacramento Metro Area. 
These measures were assessed based on the criteria specified in the 
2015 Ozone SRR and the EPA's RACT guidance, such as technical and 
economic feasibility, enforceability, local applicability, and the 
measures' ability to provide emission reductions before 2026 to advance 
attainment of the ozone standard. A summary of SACOG's findings for 
each measure is provided in Table E-6 of the 2017 Sacramento Regional 
Ozone Plan. Using the assessment criteria, SACOG concluded that none of 
the additional 22 measures that they identified were appropriate for 
implementation. Individual measures were economically infeasible, and 
when considered together, the 22 measures did not advance attainment of 
the ozone standard by one year. Based on this comprehensive review of 
TCM projects, SACOG determined that the TCMs being

[[Page 68518]]

implemented in the Sacramento Metro Area are inclusive of all RACM.\71\
---------------------------------------------------------------------------

    \71\ 2017 Sacramento Regional Ozone Plan, 7-16 and Appendix E-9, 
E-33.
---------------------------------------------------------------------------

c. CARB's RACM Analysis
    CARB's RACM analysis is contained in Appendix E-10 (``California 
Mobile Source Reasonably Available Control Measures Assessment'') of 
the 2017 Sacramento Regional Ozone Plan. This analysis provides a 
general description of CARB's existing mobile source programs. A more 
detailed description of these mobile source control programs, including 
comprehensive tables listing on- and off-road mobile source regulatory 
actions taken by CARB since as early as 1985, is contained in Section 
7.2 of the 2017 Sacramento Regional Ozone Plan. Collectively, the 
Appendix E.10 RACM analysis and Section 7.2 contain CARB's evaluation 
of mobile source and other statewide control measures that reduce 
emissions of NOX and VOC in the Sacramento Metro Area.
    Within California, CARB has primary responsibility for reducing 
emissions in several state-wide source categories, including most new 
and existing on- and off-road engines and vehicles, motor vehicle 
fuels, and consumer products. Given the need for substantial emissions 
reductions from mobile and area sources to meet the NAAQS in California 
nonattainment areas, CARB has developed stringent control measures for 
on-road and off-road mobile sources and their related fuels. California 
has authority under CAA section 209 (subject to a waiver by the EPA) to 
adopt and implement new emission standards for many categories of on-
road vehicles and engines, and new and in-use off-road vehicles and 
engines.
    CARB's mobile source program extends beyond regulations that are 
subject to the waiver or authorization process set forth in CAA section 
209 to include engine standards, gasoline and diesel fuel 
specifications, and other requirements to control emissions from in-use 
heavy-duty trucks and buses and many other types of mobile sources. 
Generally, these regulations have been submitted and approved as 
revisions to the California SIP.\72\
---------------------------------------------------------------------------

    \72\ See, e.g., 77 FR 20308 (April 4, 2012), the EPA's approval 
of standards and other requirements to control emissions from in-use 
heavy-duty diesel-powered trucks; 75 FR 26653 (May 12, 2010), 
revisions to the California on-road reformulated gasoline and diesel 
fuel regulations; and, 75 FR 38023 (July 1, 2010), revisions to the 
California motor vehicle inspection and maintenance program.
---------------------------------------------------------------------------

    Based on the strength of the measures included in the current 
statewide mobile source program, and the extensive public process 
involved in developing that program, CARB concluded that there are no 
additional RACM that would further advance attainment of the 2008 ozone 
NAAQS in the Sacramento Metro Area, and as a result, that California's 
mobile source programs fully meet the RACM requirement.\73\
---------------------------------------------------------------------------

    \73\ 2017 Sacramento Regional Ozone Plan, Appendix E.10, E-37. 
CARB's 2016 Mobile Source Strategy and the public process they 
conducted for this submittal is referenced in the appendix at 
footnote 2, E-34.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    As described above, collectively, the Districts already implement 
many rules to reduce VOC and NOX emissions from stationary 
and area sources in the Sacramento Metro Area. For the Sacramento Metro 
Area Ozone SIP, the Districts evaluated a wide range of potentially 
available measures. We find that the process followed by the Districts 
and described in the 2017 Sacramento Regional Ozone Plan to identify 
additional RACM is generally consistent with the EPA's recommendations 
in the General Preamble, that the Districts' evaluation of potential 
measures to be appropriate, and that the Districts have provided 
reasoned justifications that additional measures would not advance 
attainment. Regarding TCMs, we find that SACOG's process for 
identifying additional TCM RACM and conclusion that the TCMs being 
implemented in the Sacramento Metro Area (identified in Section 7.7 and 
Table E-6 of the 2017 Sacramento Regional Ozone Plan), are inclusive of 
all TCM RACM that are reasonably justified and supported.
    With respect to mobile sources, CARB's current program addresses 
the full range of mobile sources in the Sacramento Metro Area through 
regulatory programs for both new and in-use vehicles. We find that the 
process conducted by CARB, as described in Appendix E.10, was 
reasonably designed to identify additional available measures within 
CARB's jurisdiction, and that CARB has adopted those measures that are 
reasonably available.
    Based on our review of these RACM analyses and the Districts' and 
CARB's adopted rules, we propose to find that there are, at this time, 
no additional RACM that would further advance attainment of the 2008 
ozone NAAQS in the Sacramento Metro Area. For the foregoing reasons, we 
propose to find that the Sacramento Metro Area Ozone SIP provides for 
the implementation of all RACM as required by CAA section 172(c)(1) and 
40 CFR 51.1112(c).
    If finalized, this finding under CAA section 172(c)(1) does not 
affect the State's and the EPA's continuing obligation under CAA 
sections 182(b)(2) and (f) and 40 CFR 51.905(a)(1)(ii) to implement 
RACT on all major sources and all CTG source categories.

D. Attainment Demonstration

1. Statutory and Regulatory Requirements
    An attainment demonstration consists of the following: (1) 
Technical analyses, such as base year and future year modeling, to 
locate and identify sources of emissions that are contributing to 
violations of the ozone NAAQS within the nonattainment area (i.e., 
analyses related to the emissions inventory for the nonattainment area 
and the emissions reductions necessary to attain the standard); (2) a 
list of adopted measures (including RACT controls) with schedules for 
implementation and other means and techniques necessary and appropriate 
for demonstrating RFP and attainment as expeditiously as practicable 
but no later than the outside attainment date for the area's 
classification; (3) a RACM analysis; and, (4) contingency measures 
required under sections 172(c)(9) and 182(c)(9) of the CAA that can be 
implemented without further action by the state or the EPA to cover 
emissions shortfalls in RFP plans and failures to attain.\74\ This 
subsection of today's proposed rule addresses the first two components 
of the attainment demonstration--the technical analyses and a review of 
adopted measures. Section III.C (``Reasonably Available Control 
Measures Demonstration'') of this document addresses the RACM 
component, and section III.G (``Contingency Measures'') addresses the 
contingency measures component of the attainment demonstration in the 
Sacramento Metro Area Ozone SIP.
---------------------------------------------------------------------------

    \74\ 78 FR 34178, 34184 (June 6, 2013), the EPA's proposed rule 
for implementing the 2008 ozone NAAQS.
---------------------------------------------------------------------------

    With respect to the technical analyses, section 182(c)(2)(A) of the 
CAA requires that a plan for an ozone nonattainment area classified 
Serious or above include a ``demonstration that the plan . . . will 
provide for attainment of the ozone [NAAQS] by the applicable 
attainment date. This attainment demonstration must be based on 
photochemical grid modeling or any other analytical method determined . 
. . to be at least as effective.'' The attainment demonstration 
predicts future ambient concentrations for comparison to the NAAQS, 
making use of available information on measured

[[Page 68519]]

concentrations, meteorology, and current and projected emissions 
inventories of ozone precursors, including the effect of control 
measures in the plan. Areas classified Severe-15 for the 2008 ozone 
NAAQS must demonstrate attainment as expeditiously as practicable, but 
no later than 15 years after the effective date of designation as 
nonattainment. The Sacramento Metro Area was designated nonattainment 
for the 2008 ozone NAAQS effective July 20, 2012,\75\ and accordingly 
must demonstrate attainment of the standards by no later than July 20, 
2027.\76\ An attainment demonstration must show attainment of the 
standards for a full calendar year before the attainment date, so in 
practice, Severe-15 nonattainment areas must demonstrate attainment no 
later than 2026.
---------------------------------------------------------------------------

    \75\ 77 FR 30088 (May 21, 2012).
    \76\ 80 FR 12264 (March 6, 2015).
---------------------------------------------------------------------------

    The EPA's recommended procedures for modeling ozone as part of an 
attainment demonstration are contained in ``Modeling Guidance for 
Demonstrating Attainment of Air Quality Goals for Ozone, 
PM2.5, and Regional Haze'' (``Modeling Guidance'').\77\ The 
Modeling Guidance includes recommendations for a modeling protocol, 
model input preparation, model performance evaluation, use of model 
output for the numerical NAAQS attainment test, and modeling 
documentation. Air quality modeling is performed using meteorology and 
emissions from a base year, and the predicted concentrations from this 
base case modeling are compared to air quality monitoring data from 
that year to evaluate model performance. Once the model performance is 
determined to be acceptable, future year emissions are simulated with 
the model. The relative (or percent) change in modeled concentration 
due to future emissions reductions provides a relative response factor 
(RRF). Each monitoring site's RRF is applied to its monitored base year 
design value to provide the future design value for comparison to the 
NAAQS. The Modeling Guidance also recommends supplemental air quality 
analyses, which may be used as part of a weight of evidence (WOE) 
analysis. A WOE analysis corroborates the attainment demonstration by 
considering evidence other than the main air quality modeling 
attainment test, such as trends and additional monitoring and modeling 
analyses.
---------------------------------------------------------------------------

    \77\ ``Modeling Guidance for Demonstrating Attainment of Air 
Quality Goals for Ozone, PM2.5, and Regional Haze,'' EPA 
454/R-18-009; available at https://www.epa.gov/scram/state-implementation-plan-sip-attainment-demonstration-guidance. See also 
December 2014 draft of this guidance, available at https://www3.epa.gov/ttn/scram/guidance/guide/Draft-O3-PM-RH-Modeling_Guidance-2014.pdf. The December 2014 draft guidance was 
available during development of the Plan; the final version differs 
mainly in organization, and in updates to the regional haze portion 
and to other document references. Additional EPA modeling guidance 
can be found in 40 CFR 51 Appendix W, Guideline on Air Quality 
Models, 82 FR 5182 (January 17, 2017); available at https://www.epa.gov/scram/clean-air-act-permit-modeling-guidance.
---------------------------------------------------------------------------

    The Modeling Guidance also does not require a particular year to be 
used as the base year for 8-hour ozone plans.\78\ The Modeling Guidance 
states that the most recent year of the National Emissions Inventory 
may be appropriate for use as the base year for modeling, but that 
other years may be more appropriate when considering meteorology, 
transport patterns, exceptional events, or other factors that may vary 
from year to year.\79\ Therefore, the base year used for the attainment 
demonstration need not be the same year used to meet the requirements 
for emissions inventories and RFP.
---------------------------------------------------------------------------

    \78\ Modeling Guidance at section 2.7.1, 35.
    \79\ Id.
---------------------------------------------------------------------------

    For a more detailed discussion of photochemical modeling guidance 
recommendations, please see the technical support document (TSD) 
provided in the docket for this proposal.
    With respect to the list of adopted measures, CAA section 172(c)(6) 
requires that nonattainment area plans include enforceable emissions 
limitations, and such other control measures, means or techniques 
(including economic incentives such as fees, marketable permits, and 
auctions of emission rights), as well as schedules and timetables for 
compliance, as may be necessary or appropriate to provide for timely 
attainment of the NAAQS.\80\ Under the 2008 Ozone SRR, all control 
measures needed for attainment must be implemented no later than the 
beginning of the attainment year ozone season.\81\ The attainment year 
ozone season is defined as the ozone season immediately preceding a 
nonattainment area's maximum attainment date; in the case of the 
Sacramento Metro area, the attainment year is 2026.\82\
---------------------------------------------------------------------------

    \80\ See also CAA section 110(a)(2)(A).
    \81\ 40 CFR 51.1108(d).
    \82\ 40 CFR 51.1100(h).
---------------------------------------------------------------------------

2. Summary of the State's Submission
a. Photochemical Modeling
    CARB performed the air quality modeling for the Sacramento Metro 
Area Ozone SIP with assistance from the Districts and has included 
documentation of this modeling within the 2017 Sacramento Regional 
Ozone Plan and the CARB Staff Report. The modeling relies on a 2012 
base year and projects design values for 2022 and 2026. As discussed 
below, CARB also included an interpolation of NOX emissions 
to estimate the design value in the attainment year 2024. The 
attainment plan's modeling protocol is in Appendix B-3 of the 2017 
Sacramento Regional Ozone Plan and contains all the elements 
recommended in the Modeling Guidance.
    The modeling and modeled attainment demonstration are described in 
Chapter 6 of the 2017 Sacramento Regional Ozone Plan and in more detail 
in Appendix B-4, which provides a description of model input 
preparation procedures and various model configuration options. 
Appendix B-5 of the 2017 Sacramento Regional Ozone Plan provides the 
coordinates of the modeling domain and thoroughly describes the 
development of the modeling emissions inventory, including its chemical 
speciation, its spatial and temporal allocation, its temperature 
dependence, and quality assurance procedures. The modeling analysis 
used version 5 of the Community Multiscale Air Quality (CMAQ) 
photochemical model developed by the EPA. To prepare meteorological 
input for CMAQ, CARB used the Weather and Research Forecasting model 
version 3.6 (WRF) from the National Center for Atmospheric Research. 
The WRF modeling uses routinely available meteorological and air 
quality data collected during 2012. Those data cover May through 
September, a period that spans the period of highest ozone 
concentrations in the Sacramento Metro Area. CMAQ and WRF are both 
recognized in the Modeling Guidance as technically sound, state-of-the-
art models. The areal extent and the horizontal and vertical resolution 
used in these models were adequate for modeling Sacramento Metro Area 
ozone.
    The WRF meteorological model results and performance statistics are 
described in Appendix B-4.\83\ There is a slight underprediction of 
wind speeds and overprediction of temperatures in the eastern portion 
of the nonattainment area; but overall, modeled wind speed, temperature 
and relative humidity all track observations well, as shown in scatter 
and time series plots. The modeling was able to replicate some 
important meteorological features such as the bifurcation of the delta 
breeze from the ocean into northern and

[[Page 68520]]

southern branches, and afternoon upslope flows in the Sierra Nevada 
foothills. The 2017 Sacramento Regional Ozone Plan states that the bias 
and error are relatively small and are comparable to those seen in 
previous meteorological modeling of central California and cited in the 
2017 Sacramento Regional Ozone Plan. In summary, the 2017 Sacramento 
Regional Ozone Plan's meteorological modeling performance statistics 
appear satisfactory.
---------------------------------------------------------------------------

    \83\ Appendix B-4, section 3.2, B-125; also, refer to 
supplemental figures S.1-S.15 at B-166.
---------------------------------------------------------------------------

    Ozone model performance statistics are described in the 2017 
Sacramento Regional Ozone Plan at Appendix B-4.\84\ It includes tables 
of statistics recommended in the Modeling Guidance for 8-hour and 1-
hour daily maximum ozone concentrations, for the whole nonattainment 
area and for three Sacramento Metro Area subregions (i.e., western, 
central, and eastern. There is a slight negative bias (underprediction) 
for the central and eastern subregions. Because only the relative 
response to emissions changes from the modeling is used, note that the 
underprediction of absolute ozone concentrations does not mean that 
future concentrations will be underestimated. The 2017 Sacramento 
Regional Ozone Plan found the statistics to be within the ranges for 
other modeling applications, at the low end of the distribution for 
error and bias. The Plan's supplemental figures with hourly time series 
show generally good performance; although some individual daily ozone 
peaks are missed, for each site there are days for which the modeled 
highest concentration is close to the value of the highest observed 
concentration.
---------------------------------------------------------------------------

    \84\ Appendix B-4, section 5.2, B-139; also, refer to 
supplemental figures S.16-S.69, B-182.
---------------------------------------------------------------------------

    As noted in the 2017 Sacramento Regional Ozone Plan's modeling 
protocol, the Modeling Guidance recognizes that limited time and 
resources can constrain the extent of the diagnostic and dynamic 
evaluation of model performance undertaken.\85\ The 2017 Sacramento 
Regional Ozone Plan describes a dynamic evaluation \86\ in which model 
predictions of ozone concentrations for weekdays and weekends were 
compared to each other and to observed concentrations. This evaluation 
provides useful information on how well the model simulates the effect 
of emissions changes, since NOX emissions are lower on 
weekends than on weekdays, but otherwise similar. The model-predicted 
ozone reduction on weekends tends to match the observed ozone 
reduction; this match lends confidence to the modeling. The modeled 
weekend response is also consistent with an independent study \87\ that 
examined the frequency of ozone exceedance days over 2001-2007 and the 
NOX emission reductions during the same period. The study 
concluded the NOX reductions were effective at reducing 
ozone throughout the entire Sacramento urban ozone plume (i.e., 
downwind and northeast of urban Sacramento, within the nonattainment 
area), which exhibits ``NOX-limited'' ozone chemistry except 
in the urban core, and is expected to transition to NOX-
limited conditions everywhere in the nonattainment area as 
NOX emissions continue to decline.\88\ The Plan also 
contains results of an analysis of weekday and weekend ozone 
concentrations during the 2000-2014 period. It notes a shift over the 
years toward lower ozone on weekends, especially after 2010, showing 
that lower NOX emissions lead to lower ozone 
concentrations.\89\ Both the modeling and the observed weekday-weekend 
trends throughout the Sacramento Metro Area show that ozone responds to 
NOX emission reductions, i.e., that ozone formation is 
NOX-limited.
---------------------------------------------------------------------------

    \85\ 2017 Sacramento Regional Ozone Plan, Appendix B-3 
(``Modeling Protocol''), B-76; Modeling Guidance, 63.
    \86\ See ``Diagnostic Evaluation'' in Appendix B-4 section 
5.2.1, B-146.
    \87\ La Franchi et al., ``Observations of the temperature 
dependent response of ozone to NOX reductions in the 
Sacramento, CA urban plume,'' Atmospheric Chemistry and Physics, 11, 
6945-6960, doi:10.5194/acp-11-6945-2011, 2011; described in Appendix 
B, B-150.
    \88\ The term ``NOX-limited'' can mean either that 
reducing NOX emissions decrease ozone (as opposed to 
increasing it); or that reducing NOX is much more 
effective at decreasing ozone than is reducing VOC. Both are true in 
this case; as discussed below, ambient Sacramento Metro Area ozone 
responds only weakly to VOC reductions. The NOX-limited 
ozone regime in the Sacramento Metro Area is discussed in Plan 
Appendix B. See, e.g., B-147 through B-150 (comparing weekend-
weekday concentrations); B-150 through B-152; B-157 through B-158. 
The issue is also discussed in the CARB Staff Report Appendix B, B-
17 and B-36.
    \89\ 2017 Sacramento Regional Ozone Plan, Appendix B, B-149.
---------------------------------------------------------------------------

    After model performance for the 2012 base case was accepted, the 
model was applied to develop RRFs for the attainment demonstration.\90\ 
This entailed running the model with the same meteorological inputs as 
before, but with adjusted emissions inventories to reflect the expected 
changes between the 2012 base year and the 2022 and 2026 future years. 
These modeling inventories excluded ``emissions events which are either 
random and/or cannot be projected to the future . . . wildfires, and 
events such as the [San Francisco Bay Area] Chevron refinery fire.'' 
\91\ The future inventories project the base year with these exclusions 
into the future by including the effect of economic growth and 
emissions control measures.
---------------------------------------------------------------------------

    \90\ 2017 Sacramento Regional Ozone Plan, section 6.8, 6-10, and 
Appendix B-4, section 5.3, B-150.
    \91\ 2017 Sacramento Regional Ozone Plan, Appendix B-3 
(``Modeling Protocol''), B-78; and, Appendix B-5 (``Modeling 
Emissions Inventory''), B-259. To include the fires in the base year 
but not the future year would effectively credit the Plan's control 
measures with eliminating emissions from the fire.
---------------------------------------------------------------------------

    The 2017 Sacramento Regional Ozone Plan carried out the attainment 
test procedure consistent with the Modeling Guidance. The RRFs were 
calculated as the ratio of future to base year concentrations; these 
were then applied to 2012 weighted base year design values for each 
monitor to arrive at future year design values.\92\ The highest 2022 
ozone design value is 75.2 ppb, which occurs at the Folsom Natoma 
Street site, and just barely meets the level of the 2008 8-hour ozone 
NAAQS of 0.075 ppm.\93\ The highest 2026 ozone design value is 70.7 ppb 
at the same monitoring site, and is well below the NAAQS.
---------------------------------------------------------------------------

    \92\ 2017 Sacramento Regional Ozone Plan, Table 6-2 and Appendix 
B-4, Table 13, B-151.
    \93\ The Modeling Guidance recommends that RRFs be applied to 
the average of three three-year design values centered on the base 
year, in this case the design values for 2010-2012, 2011-2013, and 
2012-2015. This amounts to a 5-year weighted average of individual 
year 4th high concentrations, centered on the base year of 2012, and 
so is referred to as a weighted design value. 75.2 ppb is equivalent 
to 0.0752 ppm, which is truncated to 0.075 ppm according to the data 
handling conventions of 40 CFR 50 Appendix P.
---------------------------------------------------------------------------

    As discussed in chapter 8 of the 2017 Sacramento Regional Ozone 
Plan, the reduction per year needed from the monitored design value of 
83 in 2016 to the projected 75 in 2022 was roughly twice the reduction 
per year seen during 2010-2016. Given the uncertainty posed by the 
magnitude of the reductions necessary to reach this level by 2022 
relative to the historic rate of reduction, and the fact that 2022 
design values would achieve the standard by only a very small margin, 
the Districts determined that a 2024 attainment year would be more 
appropriate, while still representing an ambitious target for 
expeditious attainment in advance of the statutory outermost deadline 
for attainment.\94\ Since modeling was not available for year 2024, the 
plan interpolated between the 2022 and 2026 modeling results, on the 
basis of projected NOX emissions. The Plan's discussion of 
the weekend-weekday

[[Page 68521]]

differences, described above, notes that the area's ozone formation is 
NOX-limited, so NOX emissions are a reasonable 
basis for interpolation. The interpolation is a form of a scaling of 
model results and has been done for previous EPA-approved plans.\95\ 
The interpolation gives a 2024 design value estimate of 72.1 ppb, 
corresponding to 0.072 ppm, which is below the 2008 8-hour ozone NAAQS 
of 0.075 ppm, and therefore demonstrates attainment in 2024.\96\
---------------------------------------------------------------------------

    \94\ 2017 Sacramento Regional Ozone Plan, 8-2. Here, the year 
2024 is discussed for modeling purposes. As noted earlier, the 
effective attainment date for a determination of attainment is 
December 31, 2024 if we approve this attainment demonstration as we 
propose.
    \95\ San Joaquin Valley ``phase 2'' plan for the 2008 ozone 
NAAQS, 83 FR 61346 (November 29, 2018), and revisions to the San 
Joaquin Valley plan for the 1997 ozone NAAQS, 77 FR 12652 (March 1, 
2012).
    \96\ 2017 Sacramento Regional Ozone Plan, 8-4.
---------------------------------------------------------------------------

    Finally, the 2017 Sacramento Regional Ozone Plan modeling includes 
an ``Unmonitored Area Analysis'' (UAA) to assess whether locations 
without a monitor are able to reach attainment; the standard attainment 
test procedure covers only locations with a monitor.\97\ The Modeling 
Guidance describes a procedure utilizing ``gradient adjusted spatial 
fields,'' as well as the EPA software used to carry it out.\98\ This 
procedure uses a form of interpolation, combining monitored 
concentrations and modeled gradients (modeled changes in concentration 
with distance from a monitor) to estimate future concentrations at 
locations without a monitor. The 2017 Sacramento Regional Ozone Plan 
describes an UAA carried out using software developed by CARB and 
implemented in ``R,'' \99\ using a procedure virtually the same as that 
outlined in the Modeling Guidance. The 2017 Sacramento Regional Ozone 
Plan states that the 2026 results showed concentrations below 70 ppb 
for all locations except for one grid square at Folsom Lake; the Plan 
notes that this was likely an artifact of too-low mixing heights, a 
known problem over water. Because the results are well below the 2008 
ozone NAAQS level of 75 ppb, the UAA supports the demonstration that 
all locations in the Sacramento Metro Area will attain the NAAQS by 
2024.
---------------------------------------------------------------------------

    \97\ 2017 Sacramento Regional Ozone Plan, Appendix B-4, section 
5.4.
    \98\ Modeling Guidance section 4.7.
    \99\ The R Project for Statistical Computing, https://www.r-project.org.
---------------------------------------------------------------------------

    In addition to the formal attainment demonstration, the plan also 
contains a WOE analysis within Appendix B to the CARB Staff Report. It 
mainly shows the long-term downward trends that continue through 2015, 
the latest year available prior to 2017 Sacramento Regional Ozone Plan 
development. Downward trends are demonstrated for measured ozone 
concentrations, number of days above the ozone NAAQS, geographic area 
and population exposed to concentrations above the NAAQS, and emissions 
of the ozone precursors NOX and VOC. These all show the 
substantial air quality progress made in the Sacramento Metro Area and 
add support to the attainment demonstration for 2024.
    The 2017 Sacramento Regional Ozone Plan includes an additional 
attainment demonstration using ``banded'' RRFs; the EPA also considers 
this to be part of the WOE.\100\ The banded approach is described more 
fully in a study cited in the 2017 Sacramento Regional Ozone Plan, and 
also cited in the Modeling Guideline as an alternative RRF 
approach.\101\ The banded RRF approach divides ozone concentrations 
into ranges or bands and computes a specific RRF for each band. This 
allows different ozone concentrations to respond differently to 
emission changes, a refinement on the standard approach. In this case, 
the banded approach increased design values for some monitors and 
decreased them for others; for Folsom, the site with the highest 2026 
design value, the design value decreased from 75.2 ppb to 69.0 ppb. 
This more refined approach provides corroboration for the attainment 
demonstration and suggests that the analysis was done conservatively.
---------------------------------------------------------------------------

    \100\ 2017 Sacramento Regional Ozone Plan Appendix B-4, section 
5.5, and Appendix B-3, section 8.2.
    \101\ Modeling Guidance, 103.
---------------------------------------------------------------------------

b. Control Strategy for Attainment
    The control strategy for attainment of the 2008 ozone NAAQS in the 
2017 Sacramento Regional Ozone Plan relies primarily on emissions 
reductions from control measures that have been adopted by the 
Districts and CARB prior to the submittal of the plan. Local stationary 
and area source emissions reductions come from baseline (i.e., already-
adopted) control measures.\102\ Overall, nearly all of the emissions 
reductions that the control strategy relies upon are expected to come 
from already-adopted and EPA-approved state on- and off-road mobile 
source control measures, which are discussed in section III.C of this 
document.\103\ For the 2008 ozone NAAQS, already-adopted control 
measures from the Districts and CARB are expected to achieve almost all 
of the reductions needed from the 2012 base year to attain the 2008 
NAAQS in 2024. As tables 4 and 5 show, the vast majority of emissions 
reductions relied upon by the Plan's control strategy are from the on- 
and off-road mobile source inventory and can be largely attributed to 
control measures adopted by CARB, subsequently approved by the EPA, and 
cited in detail in Section III.C.\104\
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    \102\ 2017 Sacramento Regional Ozone Plan, Sections 7.3, 7.4, 
and 7.5, 7-12 to 7-14.
    \103\ 2017 Sacramento Regional Ozone Plan, Section 7.2, 7-1 to 
7-14.
    \104\ 2017 Sacramento Regional Ozone Plan, 5-13, Figures 5-8 and 
5-9 show VOC and NOX emission reductions by source 
category over time.

         Table 4--2012 and 2024 Volatile Organic Compound (VOC) Emissions for the Sacramento Metro Area
                                        [Summer planning inventory, tpd]
----------------------------------------------------------------------------------------------------------------
                                                                                Emissions        Percentage of
              Source category                    2012            2024        difference from     total emission
                                                                               2012 to 2024        reductions
----------------------------------------------------------------------------------------------------------------
Stationary Sources........................              22              23                 +1                 -4
Area Sources..............................              29              31                 +2                 -8
On-Road Mobile Sources....................              34              14                -20                 77
Other Mobile Sources......................              26              17                 -9                 35
                                           ---------------------------------------------------------------------
    Total.................................             110              84                -26                100
----------------------------------------------------------------------------------------------------------------
Source: 2017 Sacramento Regional Ozone Plan, Chapter 5, Table 5-1. The sum of the emissions values may not equal
  the total shown due to rounding. Percentage reductions are calculated against net total of gross reductions.

[[Page 68522]]

             Table 5--2012 and 2024 Oxides of Nitrogen (NOX) Emissions for the Sacramento Metro Area
                                        [Summer planning inventory, tpd]
----------------------------------------------------------------------------------------------------------------
                                                                                Emissions        Percentage of
              Source category                    2012            2024        difference from     total emission
                                                                               2012 to 2024        reductions
----------------------------------------------------------------------------------------------------------------
Stationary Sources........................               8               7                 -1                  2
Area Sources..............................               3               2                 -1                  2
On-Road Mobile Sources....................              61              19                -42                 81
Other Mobile Sources......................              30              21                 -9                 17
                                           ---------------------------------------------------------------------
    Total.................................             101              49                -52                100
----------------------------------------------------------------------------------------------------------------
Source: 2017 Sacramento Regional Ozone Plan, Chapter 5, Table 5-2. The sum of the emissions values may not equal
  the total shown due to rounding.

c. Attainment Demonstration
    Chapter 8 of the Plan describes the attainment demonstration in 
general terms, including photochemical modeling results, and the 
process for selecting and demonstrating a 2024 attainment year, while 
Appendix B to the Plan provides more detail concerning photochemical 
modeling. Other aspects of this demonstration are included throughout 
the Plan, including emissions inventory forecasts included in section 
5.5 and the control strategy described in Chapter 7. The WOE analysis 
in Appendix B to the CARB Staff Report includes additional supporting 
information to complement the photochemical modeling and to provide 
context for this attainment demonstration, such as analyses of 
anthropogenic emission, ambient ozone data, and meteorological 
analyses. Table 6 below summarizes the attainment demonstration for the 
2008 ozone NAAQS by listing the base year (2012) emissions level, the 
modeled attainment emissions level, and the total reductions that the 
District and CARB estimate to achieve through baseline control measures 
and accounting for growth. Baseline measures are expected to reduce 
base year (2012) emissions of NOX by 51 percent and VOC 
emissions by 24 percent by the 2024 attainment year, notwithstanding 
growth and the emission reduction credit (ERC) balance, and to attain 
the 2008 ozone NAAQS in the Sacramento Metro Area by 2024, two years 
ahead of the required attainment year, 2026.

  Table 6--Summary of Sacramento Metro Area 2008 Ozone NAAQS Attainment
                              Demonstration
                    [Summer planning inventory, tpd]
------------------------------------------------------------------------
                                                NOX             VOC
------------------------------------------------------------------------
2012 Base Year Emissions Level (A)......             101             110
2024 Modeled Attainment Emissions Level               49              84
 (B)....................................
                                         -------------------------------
    Total Reductions Needed from 2012                 52              26
     Base Year Levels to Demonstrate
     Attainment (A-B)...................
    Reductions from Baseline (i.e.,                   52              26
     adopted) Measures, net of growth
     and excluding ERC balance..........
------------------------------------------------------------------------
2024 Emissions with Reductions from                   49              84
 Baseline Control Strategy (compare to
 Row B).................................
Attainment demonstrated?................             Yes             Yes
------------------------------------------------------------------------
Notes and sources: 2017 Sacramento Regional Ozone Plan, Figure 5-8 and 5-
  9, 5-3.

3. The EPA's Review of the State's Submission
a. Photochemical Modeling
    The interpolation of 2022 and 2026 modeling results to estimate the 
2024 design value assumed that only NOX emissions needed to 
be considered; it was assumed that small changes in VOC emissions have 
a negligible effect on ozone. That assumption is supported by the ozone 
isopleth diagram in the Plan showing the ozone results from modeling 
various combinations of NOX and VOC reductions.\105\ Its 
lines of constant ozone are nearly parallel to the VOC axis; that is, 
ozone is about the same for the whole range of VOC emissions levels, 
and ozone changes very little with VOC emissions reductions. 
Conversely, the lines are nearly perpendicular to the NOX 
axis, indicating ozone varies strongly with NOX emissions 
levels. This illustrates the ozone formation is not just 
NOX-limited (responsive to NOX emissions 
changes), but also far more sensitive to emissions changes in 
NOX than VOC. On a percentage basis, ozone is about 14 times 
as sensitive to NOX reductions than to VOC reductions; on a 
tons per year basis, it is about 24 times as sensitive. Nevertheless, 
the isopleth diagram shows there is some modeled sensitivity to VOC 
change, so the EPA used it to estimate a 2024 design value, as an 
alternative to the Plan's interpolation approach. The methodology used 
is discussed in the TSD, which applies the modeled sensitivity from the 
2026 isopleth diagram to the NOX and VOC emissions 
differences between 2026 and 2024, to arrive at an ozone difference 
between 2026 and 2024. The result was a 2024 design value of 72.7 ppb, 
about 0.6 ppb higher than the Plan's estimate, but still well below the 
75 ppb NAAQS. The difference is due mainly to the different simplifying 
assumptions used in the two approaches, rather than to the inclusion of 
the effect of VOC, which by itself resulted in an impact of only 0.03 
ppb. The results corroborate the Plan's attainment demonstration, 
including the assumption that VOC emissions changes have little effect 
on ozone concentrations.\106\
---------------------------------------------------------------------------

    \105\ Plan Appendix B-4, Figure 16, p. B-158.
    \106\ The relative sensitivity of ozone to NOX and 
VOC and the alternative 2024 design value are discussed in 
``Assessment of Sacramento Metro NAA Conformity Motor Vehicle 
Emissions Budget Consistency with O3 NAAQS Attainment,'' 
draft August 7, 2020, EPA Region IX, within the docket for this 
proposed rulemaking.

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

[[Page 68523]]

    The modeling shows that existing control measures from CARB and the 
Districts are sufficient to attain the 2008 8-hour ozone NAAQS by 2024 
at all monitoring sites in the Sacramento Metro Area. Because the Plan 
properly incorporates all modeling and input preparation procedures, 
tests, and performance analyses called for in the modeling protocol, 
demonstrates good model performance, and responds to emission changes 
consistent with observations, the EPA finds that the photochemical 
modeling is adequate for purposes of supporting the attainment 
demonstration.
b. Control Strategy for Attainment
    As discussed above, the Sacramento Metro Area Ozone SIP relies on 
state and locally adopted baseline control measures, i.e., already-
adopted control measures, to achieve the emissions reductions needed to 
attain the 2008 ozone NAAQS by 2024. As shown in Tables 4-6 and 
discussed in Section III.C, the Sacramento Metro Area Ozone SIP relies 
on these measures to achieve all the emissions reductions needed to 
attain the 2008 ozone NAAQS by 2024. These baseline measures are 
approved into the SIP and, as such, are fully creditable within the 
attainment demonstration analysis. Accordingly, we propose to find that 
the emissions reductions that are relied on for attainment are 
creditable and sufficient to provide for attainment.
c. Attainment Demonstration
    The Plan followed the modeling procedures recommended in the EPA's 
Modeling Guidance and showed excellent performance in simulating 
observed ozone concentrations in the 2012 base year; the TSD discusses 
the modeling in detail. Given the extensive discussion of modeling 
procedures, tests, and performance analyses called for in the modeling 
protocol, the good model performance, and the model response to 
emissions changes consistent with observations, the EPA finds that the 
modeling is adequate for purposes of supporting the attainment 
demonstration. Based on our review of the Plan and our proposed 
findings that the photochemical modeling and control strategy are 
acceptable and demonstrate attainment by the applicable attainment 
date, we propose to approve the attainment demonstration for the 2008 
ozone NAAQS in the Sacramento Metro Area Ozone SIP as meeting the 
requirements of CAA section 182(c)(2)(A) and 40 CFR 51.1108.

E. Rate of Progress Plan and Reasonable Further Progress Demonstration

1. Statutory and Regulatory Requirements
    Requirements for RFP for ozone nonattainment areas are specified in 
CAA sections 172(c)(2), 182(b)(1), and 182(c)(2)(B). Under CAA section 
171(1), RFP is defined as meaning such annual incremental reductions in 
emissions of the relevant air pollutant as are required under part D 
(``Plan Requirements for Nonattainment Areas'') of the CAA or as may 
reasonably be required by the EPA for the purpose of ensuring 
attainment of the applicable NAAQS by the applicable date. CAA section 
182(b)(1) specifically requires that ozone nonattainment areas that are 
classified as Moderate or above demonstrate a 15 percent reduction in 
VOC between the years of 1990 and 1996. The EPA has typically referred 
to section 182(b)(1) as the rate of progress (ROP) requirement. For 
ozone nonattainment areas classified as Serious or higher, section 
182(c)(2)(B) requires VOC reductions of at least 3 percent of baseline 
emissions per year, averaged over each consecutive 3-year period, 
beginning 6 years after the baseline year until the attainment date. 
CAA section 182(c)(2)(B)(ii) allows an amount less than 3 percent of 
such baseline emissions each year if the state demonstrates to the EPA 
that the plan includes all measures that can feasibly be implemented in 
the area in light of technological achievability. Additionally, under 
CAA section 182(c)(2)(C), a state may substitute NOX 
emissions reductions for VOC emissions reductions.
    In the 2008 Ozone SRR, the EPA provides that an area classified 
Moderate or higher will have met the ROP requirements of CAA section 
182(b)(1) if the area has a fully approved 15 percent ROP plan for the 
1-hour or 1997 8-hour ozone standards, provided the boundaries of the 
ozone nonattainment areas are the same.\107\ For such areas, the EPA 
interprets the RFP requirements of CAA section 172(c)(2) to require 
areas classified as Moderate to provide a 15 percent emissions 
reduction of ozone precursors within 6 years of the baseline year. 
Areas classified as Serious or higher must meet the RFP requirements of 
CAA section 182(c)(2)(B) by providing an 18 percent reduction of ozone 
precursors in the first 6-year period, and an average ozone precursor 
emissions reduction of 3 percent per year for all remaining 3-year 
periods thereafter.\108\ To meet CAA sections 172(c)(2) and 
182(c)(2)(B) RFP requirements, a state may substitute NOX 
emissions reductions for VOC reductions.\109\
---------------------------------------------------------------------------

    \107\ 80 FR 12264, 12271 (March 6, 2015).
    \108\ Id.
    \109\ 40 CFR 51.1110(a)(2)(i)(C) and 40 CFR 
51.1110(a)(2)(ii)(B); 80 FR 12264, 12271 (March 6, 2015).
---------------------------------------------------------------------------

    Except as specifically provided in CAA section 182(b)(1)(C), 
emissions reductions from all SIP-approved, federally promulgated, or 
otherwise SIP-creditable measures that occur after the baseline year 
are creditable for purposes of demonstrating that the RFP targets are 
met. Because the EPA has determined that the passage of time has caused 
the effect of certain exclusions to be de minimis, the RFP 
demonstration is no longer required to calculate and specifically 
exclude reductions from measures related to motor vehicle exhaust or 
evaporative emissions promulgated by January 1, 1990; regulations 
concerning Reid vapor pressure promulgated by November 15, 1990; 
measures to correct previous RACT requirements; and, measures required 
to correct previous inspection and maintenance (I/M) programs.\110\
---------------------------------------------------------------------------

    \110\ 40 CFR 51.1110(a)(7).
---------------------------------------------------------------------------

    The 2008 Ozone SRR requires the RFP baseline year to be the most 
recent calendar year for which a complete triennial inventory was 
required to be submitted to the EPA. For the purposes of developing RFP 
demonstrations for the 2008 ozone NAAQS, the applicable triennial 
inventory year is 2011. As discussed above, the 2008 Ozone SRR provided 
states with the opportunity to use an alternative baseline year for 
RFP,\111\ but this provision was vacated by the D.C. Circuit in the 
South Coast II decision.
---------------------------------------------------------------------------

    \111\ 40 CFR 51.1110(b).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    In response to the South Coast II decision, CARB developed the 2018 
SIP Update, which replaces the RFP portion of the 2017 Sacramento 
Regional Ozone Plan and includes updated emissions estimates for the 
RFP baseline year, subsequent milestone years, and the attainment year, 
and an updated RFP demonstration relying on a 2011 RFP baseline 
year.\112\ To develop the 2011 RFP baseline inventory, CARB relied on 
actual emissions reported from industrial point sources for year 2011 
and back-cast emissions from smaller stationary sources and area 
sources from 2012 to 2011 using the same growth and

[[Page 68524]]

control factors as was used for the 2017 Sacramento Regional Ozone 
Plan. To develop the emissions inventories for the RFP milestone years 
(i.e., 2017, 2020, 2023) and attainment year (i.e., 2024), CARB also 
relied upon the same growth and control factors as the 2017 Sacramento 
Regional Ozone Plan. The 2018 SIP Update emissions estimates reflect 
District rules adopted and submitted to CARB through November 2015 and 
CARB rules adopted through December 2014.\113\
---------------------------------------------------------------------------

    \112\ 2018 SIP Update, Section V.B. Reasonable Further Progress, 
28-30.
    \113\ 2018 SIP Update, Appendix A, A-1, A-2.
---------------------------------------------------------------------------

    Documentation for the Sacramento Metro Area RFP baseline and 
milestone emissions inventories is found in the 2018 SIP Update.\114\ 
The updated RFP demonstration for the Sacramento Metro Area for the 
2008 ozone NAAQS is shown in Table 7. This demonstration calculates 
future year VOC targets from the 2011 baseline, consistent with CAA 
182(c)(2)(B)(i), which requires reductions of ``at least 3 percent of 
baseline emissions each year,'' and it substitutes NOX 
reductions for VOC reductions beginning in milestone year 2020 to meet 
VOC emission targets.\115\ For the Sacramento Metro Area, CARB 
concludes that the RFP demonstration meets the applicable requirements 
for each milestone year as well as the attainment year.\116\
---------------------------------------------------------------------------

    \114\ 2018 SIP Update, 27-30, and Appendix A, A-15 through A-18.
    \115\ NOX substitution is permitted under EPA 
regulations. See 40 CFR 51.1110(a)(2)(i)(C) and 40 CFR 
51.1110(a)(2)(ii)(B); and 80 FR 12264, 12271 (March 6, 2015).
    \116\ In addition to the RFP demonstration in Table 7, CARB 
provided a clarification including the small rounding additions in 
the motor vehicle emission budgets to ensure that they are accounted 
for and that RFP would still be met; email dated August 11, 2020, 
from Webster Tasat, CARB to Anita Lee, USEPA, including attached RFP 
demonstration table, in the docket.

  Table 7--RFP Demonstration for the Sacramento Metro Area for the 2008 Ozone NAAQS, Summer Planning Inventory,
                                              tpd or Percentage (%)
----------------------------------------------------------------------------------------------------------------
                                                                        VOC
                                 -------------------------------------------------------------------------------
                                       2011            2017            2020            2023            2024
----------------------------------------------------------------------------------------------------------------
Baseline VOC....................           111.6            91.7            91.3            88.5            87.9
Transportation conformity safety               0               0               0               0             0.5
 margin *.......................
Baseline + safety margin (VOC)..           111.6            91.7            91.3            88.5            88.4
Required change since 2011 (VOC   ..............              18              27              36              39
 or NOX), %.....................
Target VOC level................  ..............            91.5            81.5            71.4            68.1
Apparent shortfall (-)/surplus    ..............            -0.2            -9.9           -17.0           -20.3
 (+) in VOC.....................
Apparent shortfall (-)/surplus    ..............            -0.1            -8.8           -15.3           -18.2
 (+) in VOC, %..................
VOC shortfall previously          ..............               0            -0.1             8.8            15.3
 provided by NOX substitution, %
Actual VOC shortfall (-)/surplus  ..............            -0.1            -8.7            -6.4            -2.9
 (+), %.........................
----------------------------------------------------------------------------------------------------------------

 
                                                                        NOX
                                 -------------------------------------------------------------------------------
                                       2011            2017            2020            2023            2024
----------------------------------------------------------------------------------------------------------------
Baseline NOX....................           107.7            71.7            63.8            52.2            50.5
Transportation conformity safety               0               0             0.4             0.9             1.2
 margin *.......................
Baseline + safety margin (NOX)..           107.7            71.7            64.2            53.2            51.7
Change in NOX since 2011, tpd...  ..............            36.0            43.4            54.5            56.0
Change in NOX since 2011, %.....  ..............            33.4            40.3            50.6            52.0
NOX reductions used for VOC       ..............               0             0.1             8.8            15.3
 substitution through last
 milestone year, %..............
NOX reductions since 2011         ..............            33.4            40.2            41.8            36.7
 available for VOC substitution
 in this milestone year, %......
NOX reductions since 2011 used    ..............             0.1             8.7             6.4             2.9
 for VOC substitution in this
 milestone year, %..............
NOX reductions since 2011         ..............            33.3            31.5            35.3            33.8
 surplus after meeting VOC
 substitution needs in this
 milestone year, %..............
Total shortfall for RFP.........  ..............               0               0               0               0
RFP met?........................  ..............             Yes             Yes             Yes             Yes
----------------------------------------------------------------------------------------------------------------
Source: 2018 SIP Update, Table V-3, and Appendix A, A-15--A-18. The sum of the emissions values may not equal
  the total shown due to rounding of the numbers. Baseline emissions for 2020, 2023, and 2024 include 5 tpd VOC
  and 4 tpd NOX to account for area ERC banking and accounting.
* We discuss the concept of a safety margin within motor vehicle emissions budgets below in the Section H
  concerning transportation conformity.

3. The EPA's Review of the State's Submission
    In 2015, the EPA approved a 15 percent ROP plan for the Sacramento 
Metro Area for the 1-hour ozone NAAQS and 1997 8-hour ozone NAAQS,\117\ 
and the boundaries of the Sacramento Metro Area for the 2008 ozone 
NAAQS are the same as the Sacramento Metro Area for the 1997 8-hour 
ozone NAAQS.\118\ As a result, the Districts and CARB have met the ROP 
requirements of CAA section 182(b)(1) for the Sacramento Metro Area and 
do not need to demonstrate another 15 percent reduction in VOC for this 
area.
---------------------------------------------------------------------------

    \117\ 80 FR 4795 (January 29, 2015).
    \118\ See 2017 Sacramento Regional Ozone Plan, 2-8, Figure 2-1.
---------------------------------------------------------------------------

    Based on our review of the emissions inventory documentation in the 
2017 Sacramento Regional Ozone Plan and 2018 SIP Update, we find that 
CARB and the Districts have used the most recent planning and activity 
assumptions, emissions models, and methodologies in developing the RFP 
baseline and milestone year emissions inventories. Also, as presented 
in Table 7, we have reviewed the calculations in Table V-3 of the 2018 
SIP Update and related clarifications in CARB correspondence and find 
that the Districts and CARB have used an appropriate calculation method 
to

[[Page 68525]]

demonstrate RFP. Similarly, we find that the Districts' use of 
NOX substitution is warranted and appropriately implemented 
based on the NOX-limited conditions in the Sacramento Metro 
Area, and the area's greater responsiveness to NOX emissions 
reductions relative to VOC emissions reductions. For these reasons, we 
have determined that the Sacramento Metro Area Ozone SIP demonstrates 
RFP in each milestone year and the attainment year, consistent with 
applicable CAA requirements and EPA guidance. Therefore, we propose to 
approve the RFP demonstration for the Sacramento Metro Area for the 
2008 ozone NAAQS under sections 172(c)(2), 182(b)(1) and 182(c)(2)(B) 
of the CAA and 40 CFR 51.1110(a)(2)(ii).

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

1. Stationary and Regulatory Requirements
    Section 182(d)(1)(A) of the Act requires, in relevant part, a state 
to submit, for each area classified as Serious or above, a SIP revision 
that ``identifies and adopts specific enforceable transportation 
control strategies and transportation control measures to offset any 
growth in emissions from growth in vehicle miles traveled or number of 
vehicle trips in such area.'' \119\ Herein, we use ``VMT'' to refer to 
vehicle miles traveled and refer to the related SIP requirement as the 
``VMT emissions offset requirement.'' In addition, we refer to the SIP 
revision intended to demonstrate compliance with the VMT emissions 
offset requirement as the ``VMT emissions offset demonstration.''
---------------------------------------------------------------------------

    \119\ CAA section 182(d)(1)(A) includes three separate elements. 
In short, under section 182(d)(1)(A), states are required to adopt 
transportation control strategies and measures to offset growth in 
emissions from growth in VMT, and, as necessary, in combination with 
other emission reduction requirements, to demonstrate RFP and 
attainment. For more information on the EPA's interpretation of the 
three elements of section 182(d)(1)(A), refer to 77 FR 58067, 58068 
(September 19, 2012) (proposed withdrawal of approval of South Coast 
VMT emissions offset demonstrations). In section III.F of this 
document, we are addressing the first element of CAA section 
182(d)(1)(A) (i.e., the VMT emissions offset requirement). In 
sections III.E and III.D of this document, we are proposing to 
approve the RFP and attainment demonstrations, respectively, for the 
2008 ozone NAAQS in the Sacramento Metro Area, and compliance with 
the second and third elements of section 182(d)(1)(A) is predicated 
on final approval of the RFP and attainment demonstrations.
---------------------------------------------------------------------------

    In Association of Irritated Residents v. EPA, the United States 
Court of Appeals for the Ninth Circuit (``Court'') ruled that 
additional transportation control measures are required whenever 
vehicle emissions are projected to be higher than they would have been 
had VMT not increased, even when aggregate vehicle emissions are 
actually decreasing.\120\ In response to the Court's decision, in 
August 2012, the EPA issued a memorandum titled ``Implementing Clean 
Air Act Section 182(d)(1)(A): Transportation Control Measures and 
Transportation Control Strategies to Offset Growth in Emissions Due to 
Growth in Vehicle Miles Travelled'' (herein referred to as the ``August 
2012 Guidance'').\121\
---------------------------------------------------------------------------

    \120\ See Association of Irritated Residents v. EPA, 632 F.3d. 
584, 596-597 (9th Cir. 2011), reprinted as amended on January 27, 
2012, 686 F.3d 668, further amended February 13, 2012 (``Association 
of Irritated Residents'').
    \121\ Memorandum dated August 30, 2012, Karl Simon, Director, 
Transportation and Climate Division, Office of Transportation and 
Air Quality, to Carl Edland, Director, Multimedia Planning and 
Permitting Division, EPA Region 6, and Deborah Jordan, Director, Air 
Division, EPA Region IX.
---------------------------------------------------------------------------

    The August 2012 Guidance discusses the meaning of ``transportation 
control strategies'' (TCS) and ``transportation control measures'' 
(TCM) and recommends that both TCSs and TCMs be included in the 
calculations made for the purpose of determining the degree to which 
any hypothetical growth in emissions due to growth in VMT should be 
offset. Generally, TCS is a broad term that encompasses many types of 
controls (including, for example, motor vehicle emission limitations, 
I/M programs, alternative fuel programs, other technology-based 
measures, and TCMs) that would fit within the regulatory definition of 
``control strategy.'' \122\ TCM is defined at 40 CFR 51.100(r) as 
meaning ``any measure that is directed toward reducing emissions of air 
pollutants from transportation sources,'' including, but not limited 
to, those listed in section 108(f) of the CAA. Generally, TCMs refer to 
programs intended to reduce VMT, number of vehicle trips, or traffic 
congestion, such as programs for improved public transit, designation 
of certain lanes for passenger buses and high-occupancy vehicles, and 
trip reduction ordinances.
---------------------------------------------------------------------------

    \122\ E.g., 40 CFR 51.100(n).
---------------------------------------------------------------------------

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

[[Page 68526]]

allowed to occur under the statute as interpreted by the Court because 
it shows what would happen under a scenario in which no offsetting TCSs 
or TCMs have yet been put in place and VMT and trips are held constant 
during the period from the area's base year to its attainment year. 
This represents a ``VMT offset ceiling'' scenario. These two 
hypothetical status quo estimates are necessary steps in identifying 
the target level of emissions from which states would determine whether 
further TCMs or TCSs, beyond those that have been adopted and 
implemented in reality, would need to be adopted and implemented in 
order to fully offset any increase in emissions due solely to VMT and 
trips identified in the ``no action'' scenario.
    Finally, the state would present the emissions that are expected to 
occur in the area's attainment year after taking into account 
reductions from all enforceable TCSs and TCMs put in place after the 
baseline year. This estimate would be based on the VMT and trip levels 
expected to occur in the attainment year (i.e., the VMT and trip levels 
from the first estimate) and all of the TCSs and TCMs expected to be in 
place and for which the SIP will take credit in the area's attainment 
year, including any TCMs and TCSs put in place since the base year. 
This represents the ``projected actual'' attainment year scenario. If 
this emissions estimate is less than or equal to the emissions ceiling 
that was established in the second of the attainment year calculations, 
the TCSs or TCMs for the attainment year would be enough to fully 
offset the identified hypothetical growth in emissions.
    Alternatively, if the estimated projected actual attainment year 
emissions are still greater than the ceiling which was established in 
the second of the attainment year emissions calculations, even after 
accounting for post-baseline year TCSs and TCMs, the state would need 
to adopt and implement additional TCSs or TCMs to further offset the 
growth in emissions. The additional TCSs or TCMs would need to bring 
the actual emissions down to at least the VMT offset ceiling estimated 
in the second of the attainment year calculations, in order to meet the 
VMT offset requirement of section 182(d)(1)(A) as interpreted by the 
Court.
2. Summary of State's Submission
    CARB prepared the VMT emissions offset demonstration for the 
Sacramento Metro Area for the 2008 ozone NAAQS, and the Districts 
included it in the 2017 Sacramento Regional Ozone Plan as Appendix C 
(``VMT Offset Demonstration''). In addition to the VMT emissions offset 
demonstration, the 2017 Sacramento Regional Ozone Plan includes a 
discussion of the TCSs adopted by CARB since 1990, and a discussion of 
the TCMs developed by SACOG for the Sacramento Metro Area region as 
part of the 2016 MTP/SCS that are subject to timely implementation 
reporting requirements.\123\
---------------------------------------------------------------------------

    \123\ 2017 Sacramento Regional Ozone Plan, sections 7.2 and 7.6-
7.8.
---------------------------------------------------------------------------

    For the VMT emissions offset demonstration, CARB used EMFAC2014, 
the latest EPA-approved motor vehicle emissions model for California at 
the time the plan was produced. The EMFAC2014 model estimates the on-
road emissions from two combustion processes (i.e., running exhaust and 
start exhaust) and four evaporative processes (i.e., hot soak, running 
losses, diurnal losses, and resting losses). The EMFAC2014 model 
combines trip based VMT data from the regional transportation planning 
agency (i.e., SACOG), starts data based on household travel surveys, 
and vehicle population data from the California Department of Motor 
Vehicles. These sets of data are combined with corresponding emission 
rates to calculate emissions.
    Emissions from running exhaust, start exhaust, hot soak, and 
running losses are a function of how much a vehicle is driven. 
Emissions from these processes are thus directly related to VMT and 
vehicle trips, and CARB included emissions from them in the 
calculations that provide the basis for the Sacramento Metro Area VMT 
emissions offset demonstration. CARB did not include emissions from 
resting loss and diurnal loss processes in the analysis because such 
emissions are related to vehicle population, not to VMT or vehicle 
trips, and thus are not part of ``any growth in emissions from growth 
in vehicle miles traveled or numbers of vehicle trips in such area'' 
under CAA section 182(d)(1)(A).
    The Sacramento Metro Area VMT emissions offset demonstration uses 
2012 as the ``base year.'' The base year for VMT emissions offset 
demonstration purposes should generally be the same base year used for 
nonattainment planning purposes. In section III.A of this document, the 
EPA is proposing to approve the 2012 base year inventory for the 
Sacramento Metro Area for the purposes of the 2008 ozone NAAQS, and 
thus, CARB's selection of 2012 as the base year for the Sacramento 
Metro Area VMT emissions offset demonstration for the 2008 ozone NAAQS 
is appropriate.
    The Sacramento Metro Area VMT emissions offset demonstration also 
includes the previously described three different attainment year 
scenarios (i.e., no action, VMT offset ceiling, and projected actual). 
The 2017 Sacramento Regional Ozone Plan provides a demonstration of 
attainment of the 2008 ozone NAAQS in the Sacramento Metro Area by the 
applicable attainment date, based on the controlled 2024 emissions 
inventory. As described in section III.D of this document, the EPA is 
proposing to approve the attainment demonstration for the 2008 ozone 
NAAQS for the Sacramento Metro Area, and thus, we find CARB's selection 
of 2024 as the attainment year for the VMT emissions offset 
demonstration for the 2008 ozone NAAQS to be acceptable.
    Table 8 summarizes the relevant distinguishing parameters for each 
of the emissions scenarios and shows CARB's corresponding VOC emissions 
estimates for the demonstration for the 2008 ozone NAAQS.

                                   Table 8--VMT Emissions Offset Inventory Scenarios and Results for 2008 Ozone NAAQS
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       VMT                           Starts                 Controls      VOC emissions
                        Scenario                        ------------------------------------------------------------------------------------------------
                                                              Year          1,000/day         Year          1,000/day         Year             tpd
--------------------------------------------------------------------------------------------------------------------------------------------------------
Base Year..............................................            2012          60,570            2012          11,739            2012               28
No Action..............................................            2024          69,579            2024          11,965            2012               16
VMT Offset Ceiling.....................................            2012          60,570            2012          11,739            2012               15
Projected Actual.......................................            2024          69,579            2024          11,965            2024               11
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: 2017 Sacramento Regional Ozone Plan, Appendix C.

[[Page 68527]]

    For the base year scenario, CARB ran the EMFAC2014 model for the 
2012 base year using VMT and starts data corresponding to that year. As 
shown in Table 8, CARB estimates the Sacramento Metro Area VOC 
emissions at 28 tpd in 2012.
    For the ``no action'' scenario, CARB first identified the on-road 
motor vehicle control programs (i.e., TCSs or TCMs) put in place since 
the base year and incorporated into EMFAC2014 and then ran EMFAC2014 
with the VMT and starts data corresponding to the 2024 attainment year 
without the emissions reductions from the on-road motor vehicle control 
programs put in place after the base year. Thus, the no action scenario 
reflects the hypothetical VOC emissions that would occur in the 
attainment year in the Sacramento Metro Area if CARB had not put in 
place any additional TCSs or TCMs after 2012. As shown in Table 8, CARB 
estimates the ``no action'' Sacramento Metro Area VOC emissions at 16 
tpd in 2024.
    For the ``VMT offset ceiling'' scenario, CARB ran the EMFAC2014 
model for the attainment years but with VMT and starts data 
corresponding to base year values. Like the no action scenario, the 
EMFAC2014 model was adjusted to reflect the VOC emissions levels in the 
attainment years without the benefits of the post-base-year on-road 
motor vehicle control programs. Thus, the VMT offset ceiling scenario 
reflects hypothetical VOC emissions in the Sacramento Metro Area if 
CARB had not put in place any TCSs or TCMs after the base year and if 
there had been no growth in VMT or vehicle trips between the base year 
and the attainment year.
    The hypothetical growth in emissions due to growth in VMT and trips 
can be determined from the difference between the VOC emissions 
estimates under the ``no action'' scenario and the corresponding 
estimates under the ``VMT offset ceiling'' scenario. Based on the 
values in Table 8, the hypothetical growth in emissions due to growth 
in VMT and trips in the Sacramento Metro Area would have been 1 tpd 
(i.e., 16 tpd minus 15 tpd). This hypothetical difference establishes 
the level of VMT growth-caused emissions that need to be offset by the 
combination of post-baseline year TCMs and TCSs and any necessary 
additional TCMs and TCSs.
    For the ``projected actual'' scenario calculation, CARB ran the 
EMFAC2014 model for the attainment year with VMT and starts data at 
attainment year values and with the full benefits of the relevant post-
baseline year motor vehicle control programs. For this scenario, CARB 
included the emissions benefits from TCSs and TCMs put in place since 
the base year. The most significant measures reducing VOC emissions 
during the 2012 to 2024 timeframe include the ACC program, ZEV 
requirements, and more stringent on-board diagnostics 
requirements.\124\
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    \124\ Section 7.2 of the 2017 Sacramento Regional Ozone Plan 
includes a discussion of the State's transportation control 
strategies adopted by CARB since 1990. Also, refer to the EPA's 
final actions on CARB mobile source SIP submittals at 81 FR 39424 
(June 16, 2016), 82 FR 14446 (March 21, 2017), and 83 FR 23232 (May 
18, 2018).
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    As shown in Table 8, the projected actual attainment-year VOC 
emissions is 11 tpd. CARB then compared this value against the 
corresponding VMT offset ceiling value to determine whether additional 
TCMs or TCSs would need to be adopted and implemented in order to 
offset any increase in emissions due solely to VMT and trips. Because 
the projected actual emissions are less than the corresponding VMT 
offset ceiling emissions, CARB concluded that the demonstration shows 
compliance with the VMT emissions offset requirement and that there are 
sufficient adopted TCSs and TCMs to offset the growth in emissions from 
the growth in VMT and vehicle trips in the Sacramento Metro Area for 
the 2008 ozone NAAQS.
3. The EPA's Review of the State's Submission
    Based on our review of revised Sacramento Metro Area VMT emissions 
offset demonstration in Appendix C of the 2017 Sacramento Regional 
Ozone Plan, we find CARB's analysis to be consistent with the August 
2012 Guidance and consistent with the emissions and vehicle activity 
estimates found elsewhere in the 2017 Sacramento Regional Ozone Plan. 
We agree that CARB and SACOG have adopted sufficient TCSs and TCMs to 
offset the growth in emissions from growth in VMT and vehicle trips in 
the Sacramento Metro Area for the purposes of the 2008 ozone NAAQS. As 
such, we propose to approve the Sacramento Metro Area VMT emissions 
offset demonstration element of the Sacramento Metro Area Ozone SIP as 
meeting the requirements of CAA section 182(d)(1)(A).

G. Contingency Measures

1. Statutory and Regulatory Requirements
    Under the CAA, 8-hour ozone nonattainment areas classified under 
subpart 2 as Moderate or above must include in their SIPs contingency 
measures consistent with sections 172(c)(9) and 182(c)(9). Contingency 
measures are additional controls or measures to be implemented in the 
event the area fails to make RFP or to attain the NAAQS by the 
attainment date. The SIP should contain trigger mechanisms for the 
contingency measures, specify a schedule for implementation, and 
indicate that the measure will be implemented without significant 
further action by the state or the EPA.\125\
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    \125\ 70 FR 71612 (November 29, 2005). Also, see the 2008 Ozone 
SRR, 80 FR 12264, 12285 (March 6, 2015).
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    Neither the CAA nor the EPA's implementing regulations establish a 
specific level of emissions reductions that implementation of 
contingency measures must achieve, but the EPA's 2008 Ozone SRR 
reiterates the EPA's policy that contingency measures should generally 
provide for emissions reductions approximately equivalent to one year's 
worth of progress, amounting to reductions of 3 percent of the baseline 
emissions inventory for the nonattainment area.\126\ Where a failure to 
attain or meet RFP can be corrected in less than one year, the EPA may 
accept a proportionally lesser amount sufficient to correct the 
identified failure.\127\
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    \126\ 80 FR 12264, 12285 (March 6, 2015).
    \127\ General Preamble, 57 FR 13498, 13511 (April 16, 1992).
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    It has been the EPA's longstanding interpretation of CAA section 
172(c)(9) that states may meet the contingency measure requirement by 
relying on federal measures (e.g., federal mobile source measures based 
on the incremental turnover of the motor vehicle fleet each year) and 
local measures already scheduled for implementation that provide 
emissions reductions in excess of those needed to provide for RFP or 
expeditious attainment. The key is that the Act requires that 
contingency measures provide for additional emissions reductions that 
are not relied on for RFP or attainment and that are not included in 
the RFP or attainment demonstrations as meeting part of or all the 
contingency measure requirements. The purpose of contingency measures 
is to provide continued emissions reductions while a plan is being 
revised to meet the missed milestone or attainment date.
    The EPA has approved numerous SIPs under this interpretation--i.e., 
SIPs that use as contingency measures one or more federal or local 
measures that are in place and provide reductions that are in excess of 
the reductions required by the attainment demonstration or RFP 
plan,\128\ and there is case law

[[Page 68528]]

supporting the EPA's interpretation in this regard.\129\ However, in 
Bahr v. EPA, the Ninth Circuit rejected the EPA's interpretation of CAA 
section 172(c)(9) as allowing for early implementation of contingency 
measures.\130\ The Ninth Circuit concluded that contingency measures 
must take effect at the time the area fails to make RFP or attain by 
the applicable attainment date, not before.\131\ Consequently, within 
the geographic jurisdiction of the Ninth Circuit, states cannot rely on 
early-implemented measures to comply with the contingency measure 
requirements under CAA section 172(c)(9) and 182(c)(9).\132\
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    \128\ See, e.g., 62 FR 15844 (April 3, 1997) (direct final rule 
approving an Indiana ozone SIP revision); 62 FR 66279 (December 18, 
1997) (final rule approving an Illinois ozone SIP revision); 66 FR 
30811 (June 8, 2001) (direct final rule approving a Rhode Island 
ozone SIP revision); 66 FR 586 (January 3, 2001) (final rule 
approving District of Columbia, Maryland, and Virginia ozone SIP 
revisions); and 66 FR 634 (January 3, 2001) (final rule approving a 
Connecticut ozone SIP revision).
    \129\ See, e.g., LEAN v. EPA, 382 F.3d 575 (5th Cir. 2004) 
(upholding contingency measures that were previously required and 
implemented where they were in excess of the attainment 
demonstration and RFP SIP).
    \130\ Bahr v. EPA, 836 F.3d 1218, 1235-1237 (9th Cir. 2016).
    \131\ Id. at 1235-1237.
    \132\ The Bahr v. EPA decision involved a challenge to an EPA 
approval of contingency measures under the general nonattainment 
area plan provisions for contingency measures in CAA section 
172(c)(9), but, given the similarity between the statutory language 
in section 172(c)(9) and the ozone-specific contingency measure 
provision in section 182(c)(9), we find that the decision affects 
how both sections of the Act must be interpreted.
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2. Summary of the State's Submission
    The District and CARB had largely prepared the 2017 Sacramento 
Regional Ozone Plan prior to the Bahr v. EPA decision; therefore, the 
plan relies solely upon surplus emissions reductions from already 
implemented control measures in the RFP milestone years to demonstrate 
compliance with the RFP milestone contingency measure requirements of 
CAA sections 172(c)(9) and 182(c)(9).\133\
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    \133\ 2017 Sacramento Regional Ozone Plan, 7-18, 8-5 and 12-5.
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    In the 2018 SIP Update, CARB revised the RFP demonstration for the 
2008 ozone NAAQS for the Sacramento Metro Area and recalculated the 
extent of surplus emission reductions (i.e., surplus to meeting the RFP 
milestone requirement for a given milestone year) in the milestone 
years. In light of the Bahr v. EPA decision, the 2018 SIP Update, 
however, does not rely on the surplus or incremental emissions 
reductions to comply with the contingency measures requirements of 
sections 172(c)(9) and 182(c)(9) but, to provide context in which to 
review contingency measures for the 2008 ozone NAAQS, the 2018 SIP 
Update documents the extent to which future baseline emissions would 
provide surplus emissions reductions beyond those required to meet 
applicable RFP milestones. More specifically, the 2018 SIP Update 
identifies one year's worth of RFP as approximately 3.3 tpd and 
estimates surplus NOX reductions as ranging from 
approximately 35.8 tpd to 38.1 tpd depending upon the given RFP 
milestone year.\134\
---------------------------------------------------------------------------

    \134\ 2018 SIP Update, chapter V, tables V-5 and V-6.
---------------------------------------------------------------------------

    To comply with sections 172(c)(9) and 182(c)(9), as interpreted in 
the Bahr v. EPA decision, a state must develop, adopt and submit a 
contingency measure to be triggered upon a failure to meet RFP 
milestones or failure to attain the NAAQS by the applicable attainment 
date regardless of the extent to which already-implemented measures 
would achieve surplus emissions reductions beyond those necessary to 
meet RFP milestones and beyond those predicted to achieve attainment of 
the NAAQS. Therefore, to fully address the contingency measure 
requirement for the 2008 ozone NAAQS in the Sacramento Metro Area, the 
Districts have committed to develop, adopt and submit contingency 
measures to CARB in sufficient time for CARB to submit the contingency 
measures as a SIP revision to the EPA within 12 months of the EPA's 
final conditional approval of the contingency measure element of the 
Sacramento Metro Area Ozone SIP.\135\
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    \135\ Letter dated May 26, 2020, from the Districts respective 
Executive Officer or Air Pollution Control Officer, Alberto Ayala-
SMAQMD, Dave Johnston-EDCAQMD, Christopher Brown-FRAQMD, Erik White-
PCAPCD, Mat Ehrhardt-YSAQMD to Richard Corey, Executive Officer, 
CARB.
---------------------------------------------------------------------------

    The Districts' commitment is to amend or adopt the rules listed 
below, through the required public review and subsequent District board 
approval processes, to apply more stringent requirements upon a 
determination that the Sacramento Metro Area failed to meet an RFP 
milestone or failed to attain the 2008 ozone NAAQS by the applicable 
attainment date. The Districts' specific commitments are described 
below.
     The Districts will amend their respective ``Architectural 
Coatings'' rule (i.e., FRAQMD Rule 315, EDAQMD Rule 245, SMAQMD Rule 
442, PCAPCD Rule 218, and YSAQMD Rule 2.14) to lower the VOC limit for 
several coating categories, delete coating categories for non-flats, 
stains, floor, and other specialty coatings, and establish new VOC 
content limits for colorants.
     The SMAQMD will adopt a new rule for reducing VOC 
emissions from liquified petroleum gas transfer and dispensing 
commensurate with South Coast Air Quality Management District Rule 
1177.
    CARB has committed to adopt and submit the revised rules to the EPA 
within 12 months of the EPA's final conditional approval of the 
contingency measure element of the Sacramento Metro Area Ozone 
SIP.\136\ Within its 2018 SIP Update, CARB estimated that nonattainment 
area VOC and NOX emissions are expected to be approximately 
0.5 and 1.8 tpd, respectively, or 2.3 tpd lower in 2025 than in 2024. 
Also, in their commitment letter, the Districts estimated the potential 
additional emission reductions from their contingency measure 
commitments at 0.6 tpd of VOC.
---------------------------------------------------------------------------

    \136\ Letter dated July 7, 2020, from Richard W. Corey, 
Executive Officer, CARB, to John Busterud, Regional Administrator, 
EPA Region IX.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    Sections 172(c)(9) and 182(c)(9) require contingency measures to 
address potential failure to achieve RFP milestones or failure to 
attain the NAAQS by the applicable attainment date. To evaluate the 
contingency measure element of the Sacramento Metro Area Ozone SIP, we 
find it useful to distinguish between contingency measures to address 
potential failure to achieve RFP milestones (``RFP contingency 
measures'') and contingency measures to address potential failure to 
attain the NAAQS (``attainment contingency measures'').
    With respect to the RFP contingency measure requirement, we have 
reviewed the surplus emissions estimates in each of the RFP milestone 
years, as shown in the 2018 SIP Update, and find that the calculations 
are correct. Therefore, we agree that the Sacramento Metro Area Ozone 
SIP provides surplus emissions reductions well beyond those necessary 
to demonstrate RFP in all the RFP milestone years. While such surplus 
emissions reductions in the RFP milestone years do not represent 
contingency measures themselves, we believe they are relevant in 
evaluating the adequacy of RFP contingency measures that are submitted 
(or will be submitted) to meet the requirements of sections 172(c)(9) 
and 182(c)(9).
    In this case, the Districts and CARB have committed to develop, 
adopt, and submit revised and new rules as an RFP contingency measure 
within 12 months of our final action on the Sacramento Metro Area Ozone 
SIP. The specific

[[Page 68529]]

types of revisions the Districts have committed to make upon an RPF 
milestone failure (i.e., increasing the stringency of existing 
requirements and adopting a new rule) comply with the requirements in 
CAA sections 172(c)(9) and 182(c)(9) because they would be undertaken 
if the area fails to meet an RFP milestone and would take effect 
without significant further action by the state or the EPA.
    Next, we considered the adequacy of the RFP contingency measure 
(once adopted and submitted) from the standpoint of the magnitude of 
emissions reductions the measure would provide if triggered. Neither 
the CAA nor the EPA's implementing regulations for the ozone NAAQS 
establish a specific amount of emissions reductions that implementation 
of contingency measures must achieve, but we generally expect that 
contingency measures should provide for emissions reductions 
approximately equivalent to one year's worth of RFP, which, for ozone, 
amounts to reductions of 3 percent of the baseline emissions inventory 
for the nonattainment area. For the 2008 ozone NAAQS in the Sacramento 
Metro Area, one year's worth of RFP is approximately 3.3 tpd of VOC or 
NOX reductions.\137\ In their commitment letter, the 
Districts estimated the potential additional emission reductions from 
their contingency measure commitments at 0.6 tpd, an amount less than 
one year's worth of RFP.
---------------------------------------------------------------------------

    \137\ The 2011 baseline for VOC and NOX is 111.6 tpd 
and 107.7 tpd, respectively, as shown in tables V-1 of the 2018 SIP 
Update. Three percent of these baselines is 3.3 tpd of VOC and 3.2 
tpd of NOX.
---------------------------------------------------------------------------

    The 2018 SIP Update, however, provides the larger SIP planning 
context with which to judge the adequacy of the to-be-submitted 
District contingency measures by calculating the surplus emissions 
reductions estimated to be achieved in the RFP milestone years and the 
year after the attainment year. More specifically, the 2018 SIP Update 
identified surplus NOX reductions in the various RFP 
milestone years for the Sacramento Metro Area. The estimates of surplus 
NOX reductions range from 33.9 to 38.1 tpd, depending on the 
RFP year, and are ten or more times greater than one year's worth of 
progress (3.2 tpd of NOX).\138\ The surplus reflects already 
implemented regulations and is primarily the result of vehicle 
turnover, which refers to the ongoing replacement by individuals, 
companies, and government agencies of older, more polluting vehicles 
and engines with newer vehicles and engines. In light of these surplus 
NOX emissions reductions in the RFP milestone years, the 
emissions reductions from the Districts' contingency measures are 
adequate to meet the contingency measure requirements of the CAA with 
respect to RFP milestones, even though the measures by themselves 
produce fewer emission reductions than what the EPA normally recommends 
for reductions from such contingency measures.
---------------------------------------------------------------------------

    \138\ 2018 SIP Update, Table V-6.
---------------------------------------------------------------------------

    For attainment contingency measure purposes, we evaluate the 
emissions reductions from the Districts' contingency measures in the 
context of the expected reduction in emissions within the Sacramento 
Metro Area in the year following the attainment year relative to those 
occuring in the attainment year. Based on the emission inventories in 
Appendix A to the 2018 SIP Update, we note that nonattainment area VOC 
and NOX emissions are expected to be approximately 0.5 and 
1.8 tpd, respectively, or 2.3 tpd lower in 2025 than in 2024. When 
considered together, these baseline measures and the Districts' 
contingency measures provide for an emissions reduction (2.9 tpd) that 
is near to, but slightly below, one year's worth of progress (i.e., 3.3 
tpd of VOC). Given that the attainment demonstration interpolates a 
2024 design value (0.072 ppm) well below the 2008 8-hour ozone NAAQS 
(0.075 ppm), we project that this amount will be sufficient to correct 
any failure to attain the 2008 8-hour ozone NAAQS in less than one year 
from the attainment date; therefore, these estimated emission 
reductions represent continued progress for purposes of the attainment 
contingency measure requirements.
    For these reasons, we propose to conditionally approve the 
contingency measures element of the Sacramento Metro Area Ozone SIP, as 
supplemented by the commitments from the Districts and CARB to adopt 
and submit additional contingency measures, to meet the contingency 
measure requirements of CAA sections 172(c)(9) and 182(c)(9). Our 
proposed approval is conditional because it relies upon commitments to 
adopt and submit specific enforceable contingency measures (i.e., 
revised rules with contingent provisions). Conditional approvals are 
authorized under CAA section 110(k)(4).

H. Motor Vehicle Emissions Budgets for Transportation Conformity

1. Statutory and Regulatory Requirements
    Section 176(c) of the CAA requires federal actions in nonattainment 
and maintenance areas to conform to the SIP's goals of eliminating or 
reducing the severity and number of violations of the NAAQS and 
achieving timely attainment of the standards. Conformity to the SIP's 
goals means that such actions will not: (1) Cause or contribute to 
violations of a NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal 
Transit Administration (FTA) funding or approval are subject to the 
EPA's transportation conformity rule, codified at 40 CFR part 93, 
subpart A. Under this rule, metropolitan planning organizations (MPOs) 
in nonattainment and maintenance areas coordinate with state and local 
air quality and transportation agencies, the EPA, the FHWA, and the FTA 
to demonstrate that an area's regional transportation plans and 
transportation improvement programs conform to the applicable SIP. This 
demonstration is typically done by showing that estimated emissions 
from existing and planned highway and transit systems are less than or 
equal to the motor vehicle emissions budgets (MVEBs or ``budgets'') 
contained in all control strategy SIPs. Budgets are generally 
established for specific years and specific pollutants or precursors. 
Ozone plans should identify budgets for on-road emissions of ozone 
precursors (NOX and VOC) in the area for each RFP milestone 
year and, if the plan demonstrates attainment, the attainment 
year.\139\
---------------------------------------------------------------------------

    \139\ 40 CFR 93.102(b)(2)(i).
---------------------------------------------------------------------------

    For budgets to be approvable, they must meet, at a minimum, the 
EPA's adequacy criteria at 40 CFR 93.118(e)(4). To meet these 
requirements, the budgets must be consistent with the attainment and 
RFP requirements and reflect all the motor vehicle control measures 
contained in the attainment and RFP demonstrations.\140\ Budgets may 
include a safety margin representing the difference between projected 
emissions and the total amount of emissions estimated to satisfy any 
requirements for attainment or RFP.
---------------------------------------------------------------------------

    \140\ 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more 
information on the transportation conformity requirements and 
applicable policies on MVEBs, please visit our transportation 
conformity website at: http://www.epa.gov/otaq/stateresources/transconf/index.htm.
---------------------------------------------------------------------------

    The EPA's process for determining adequacy of a budget consists of 
three basic steps: (1) Providing public notification of a SIP 
submission; (2) providing the public the opportunity to comment on the 
budget during a public

[[Page 68530]]

comment period; and (3) making a finding of adequacy or 
inadequacy.\141\
---------------------------------------------------------------------------

    \141\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The 2017 Sacramento Regional Ozone Plan includes budgets for the 
2018 and 2021 RFP milestone years, and the 2024 attainment year. The 
budgets for 2018, 2021, and 2024 were derived from the 2012 RFP 
baseline year and the associated RFP milestone years. Consequently, 
these budgets are affected by the South Coast II decision vacating the 
alternative baseline year provision; therefore, the EPA has not acted 
on the budgets.
    On December 5, 2018, CARB submitted the 2018 SIP Update, which 
revises the RFP demonstration consistent with the South Coast II 
decision (i.e., by using a 2011 RFP baseline year) and identifies new 
VOC and NOX budgets for the Sacramento Metro Area for each 
updated RFP milestone year, 2020 and 2023, and for the attainment year, 
2024. The budgets in the 2018 SIP Update replace the budgets contained 
in the 2017 Sacramento Regional Ozone Plan. In the submittal letter for 
the 2018 SIP Update, CARB requested that the EPA limit the duration of 
our approval of the budgets in the 2018 SIP Update to last only until 
the effective date of future EPA adequacy findings for replacement 
budgets.\142\ Subsequent to this request, CARB has decided not to limit 
the duration of the budgets submitted in the 2018 SIP Update.\143\
---------------------------------------------------------------------------

    \142\ Letter dated December 5, 2018, from Richard Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX.
    \143\ Email dated September 9, 2020, from Nesamani Kalandiyur, 
CARB, to Jerry Wamsley, EPA Region IX.
---------------------------------------------------------------------------

    Like the budgets in the 2017 Sacramento Regional Ozone Plan, the 
budgets in the 2018 SIP Update were calculated using EMFAC2014, CARB's 
latest approved version of the EMFAC model for estimating emissions 
from on-road vehicles operating in California available at the time the 
2018 SIP Update was developed. The 2018 SIP Update budgets are rounded 
up to the nearest whole number, after adding safety margins in specific 
years for specific pollutants. The following safety margins have been 
added to the baseline budgets: 0.5 tpd of VOC in 2024; 0.41 tpd of 
NOX in 2020; 0.92 tpd of NOX in 2020; and 1.17 
tpd of NOX in 2024.\144\ These safety margins are included 
to accommodate increased emissions seen in EMFAC2017, the EMFAC model 
that will likely be used in future conformity determinations.\145\ The 
conformity budgets for NOX and VOC in the 2018 SIP Update 
for the Sacramento Metro Area are provided in Table 9.
---------------------------------------------------------------------------

    \144\ 2018 SIP Update, 31, Table V-4.
    \145\ As previously noted, EMFAC2014 is CARB's model for 
estimating emissions from on-road vehicles operating in California; 
80 FR 77337 (December 14, 2015). We have recently announced the 
availability of an updated version of EMFAC, referred to as 
EMFAC2017; 84 FR 41717 (August 15, 2019). For the 2017 Sacramento 
Regional Ozone Plan and the 2018 SIP Update, EMFAC2014 was the 
appropriate model to use for SIP development purposes at the time 
the Plan and update were prepared.

 Table 9--Transportation Conformity Motor Vehicle Emissions Budgets for
            the 2008 Ozone NAAQS in the Sacramento Metro Area
                    [Summer planning inventory, tpd]
------------------------------------------------------------------------
                  Budget year                       VOC          NOX
------------------------------------------------------------------------
2023..........................................           15           22
2024..........................................           15           21
------------------------------------------------------------------------
Source: Table V-4 of the 2018 SIP Update.

    The budgets in the 2018 SIP Update reflect VMT estimates from 
SACOG's long range 2016 MTP/SCS as updated in the 2017 MTIP-20 
Metropolitan Transportation; \146\ SACOG also coordinated with the MTC 
in obtaining and using transportation data for the eastern portion of 
Solano County that is in the Sacramento Metro Area.\147\
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    \146\ 2018 SIP Update, 31; 2017 Sacramento Regional Ozone Plan, 
10-2--10-6.
    \147\ 2017 Sacramento Regional Ozone Plan, Sections 10.4 and 
10.5. 2018 SIP Update, 31.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    As part of our review of the approvability of the budgets in the 
Sacramento Metro Area Ozone SIP, we have evaluated the budgets using 
our adequacy criteria specified in the transportation conformity 
rule.\148\ We will complete the adequacy review concurrent with our 
final action on the Sacramento Metro Area Ozone SIP. The EPA is not 
required under its transportation conformity rule to find budgets 
adequate prior to our proposing approval of them.\149\ Today, the EPA 
is announcing that the adequacy process for these budgets begins, and 
the public has 30 days to comment on the budgets presented here and in 
the Sacramento Metro Area Ozone SIP.\150\
---------------------------------------------------------------------------

    \148\ 40 CFR 93.118(e)(4) and (5).
    \149\ Under the transportation conformity regulations, the EPA 
may review the adequacy of submitted motor vehicle emission budgets 
simultaneously with the EPA's approval or disapproval of the 
submitted implementation plan. 40 CFR 93.118(f)(2).
    \150\ 40 CFR 93.118(f)(2)(i) and (ii).
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    As documented in a memorandum included in the docket for this 
rulemaking, we provisionally conclude that the budgets in the 
Sacramento Metro Area Ozone SIP meet each adequacy criterion.\151\ In 
this memorandum, we evaluated the safety margins and rounding margins 
that CARB added to the baseline budgets. Given the use of updated 
travel data in the motor vehicle emissions estimates, the safety 
margins, and CARB's convention of rounding emissions up to the nearest 
whole number, there are small differences between the budgets and the 
planning emissions inventories in the 2018 SIP Update and the 2017 
Sacramento Regional Ozone Plan. We examined the potential effect of 
those differences and found that the inclusion of the small motor 
vehicle emissions budget increases would still result in demonstrations 
that show RFP and attainment are met.\152\
---------------------------------------------------------------------------

    \151\ Memorandum dated September 17, 2020, from Jerry Wamsley, 
Air Planning Office, EPA Region IX, titled ``Adequacy Review of 
Motor Vehicle Emissions Budgets in California's Sacramento Metro 
Area Ozone SIP for the 2008 National Ambient Air Quality Standard 
for Ozone.''
    \152\ Id. In our Memorandum, we summarize and reference 
``Assessment of Sacramento Metro NAA Conformity Motor Vehicle 
Emissions Budget Consistency with O3 NAAQS Attainment,'' 
September 14, 2020, EPA Region IX, which provides the EPA's more 
detailed discussion and calculations concerning the 2018 SIP Update 
effects, along with the companion Excel spreadsheet, (Copy of) 
Sac_O3_scaling _for_Update_MVEB.xlsx; both are in the docket for 
this rulemaking.
---------------------------------------------------------------------------

    While a finding of adequacy and approval are two separate actions, 
reviewing the budgets for their adequacy against the criteria in the 
transportation conformity rule informs the EPA's decision to propose 
our approval of the budgets. We have completed our detailed review of 
the Sacramento Metro Area Ozone SIP and are proposing herein to approve 
the attainment and RFP demonstrations in sections III.D and III.E, 
respectively. We have also reviewed the budgets in the Sacramento Metro 
Area Ozone SIP and found that they are consistent with the attainment 
and RFP demonstrations for which we are proposing approval, are based 
on control measures that have already been adopted and implemented, and 
meet all other applicable statutory and regulatory requirements 
including the adequacy criteria in 40 CFR 93.1118(e)(4) and (5). 
Therefore, we are proposing to approve the 2023 RFP budget and the 2024 
RFP/attainment budget in the Sacramento Metro Area Ozone SIP. At the 
time when we either finalize the adequacy process or approve the 
budgets for the 2008 ozone NAAQS in the Sacramento Metro Area

[[Page 68531]]

Ozone SIP, as proposed (whichever occurs first; note that they could 
also occur concurrently per 40 CFR 93.118(f)(2)(iii)), they will 
replace the budgets that we previously found adequate for use in 
transportation conformity determinations.\153\
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    \153\ On July 25, 2014, we found adequate the 2017 and 2018 
budgets from the ``Sacramento Regional 8-Hour Ozone Attainment Plan 
and Reasonable Further Progress Plan,'' September 26, 2013; 79 FR 
46436 (August 8, 2014). This plan and the budgets were approved in 
January 2015; 80 FR 4795 (January 29, 2015). The budgets are as 
follows: For VOC, 18 tpd for 2017 and 17 tpd for 2018; and for 
NOX, 39 tpd for 2017 and 37 tpd for 2018.
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I. Other Clean Air Act Requirements Applicable to Severe Ozone 
Nonattainment Areas

    In addition to the SIP requirements discussed in the previous 
sections, the CAA includes certain other SIP requirements applicable to 
Severe ozone nonattainment areas, such as the Sacramento Metro Area. We 
describe these provisions and their current status below.
1. Enhanced Vehicle Inspection and Maintenance Programs
    Section 182(c)(3) of the CAA requires states with ozone 
nonattainment areas classified under subpart 2 as Serious or above to 
implement an enhanced motor vehicle inspection/maintenance (I/M) 
program in those areas. The requirements for those programs are 
provided in CAA section 182(c)(3) and 40 CFR part 51, subpart S.
    Consistent with the 2008 Ozone SRR, no new I/M programs are 
currently required for nonattainment areas for the 2008 ozone 
NAAQS.\154\ The EPA previously approved California's I/M program in the 
Sacramento Metro Area as meeting the requirements of the CAA and 
applicable EPA regulations for enhanced I/M programs.\155\
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    \154\ 2008 Ozone SRR, 80 FR 12264, 12283 (March 6, 2015).
    \155\ 75 FR 38023 (July 1, 2010).
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2. New Source Review Rules
    Section 182(a)(2)(C) of the CAA requires a state to develop SIP 
revisions containing permit programs for each of its ozone 
nonattainment areas. The SIP revisions are to include requirements for 
permits in accordance with CAA sections 172(c)(5) and 173 for the 
construction and operation of each new or modified major stationary 
source for VOC and NOX anywhere in the nonattainment area. 
The EPA has previously approved the Districts' new source review (NSR) 
rules into the SIP based on our conclusion that the rules adequately 
addressed the NSR requirements.\156\ We will address the NSR 
requirements for the 2008 ozone NAAQS in the Sacramento Metro Area in a 
separate action.
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    \156\ The Districts' NSR rules were approved by the EPA as 
follows: EDCAQMD Rule 523, 65 FR 4887 (February 5, 2000); FRAQMD 
Rule 10.1, 80 FR 60047 (October 5, 2015); PCAPCD Rule 502, 79 FR 
58264 (September 29, 2014); SMAQMD Rule 214, 78 FR 53271 (August 29, 
2013); and YSAQMD Rule 3.4, 62 FR 36214 (July 7, 1997).
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3. Clean Fuels Fleet Program
    Sections 182(c)(4)(A) and 246 of the CAA require California to 
submit to the EPA for approval measures to implement a Clean Fuels 
Fleet Program in ozone nonattainment areas classified as Serious and 
above. Section 182(c)(4)(B) of the CAA allows states to opt out of the 
federal clean-fuel vehicle fleet program by submitting a SIP revision 
consisting of a program or programs that will result in at least 
equivalent long-term reductions in ozone precursors and toxic air 
emissions.
    In 1994 CARB submitted a SIP revision to the EPA to opt out of the 
federal Clean Fuels Fleet Program. The submittal included a 
demonstration that California's low-emissions vehicle program achieved 
emissions reductions at least as large as would be achieved by the 
federal program. The EPA approved the SIP revision to opt out of the 
federal program on August 27, 1999.\157\ There have been no changes to 
the federal Clean Fuels Fleet Program since the EPA approved the 
California SIP revision to opt out of the federal program; therefore, 
no corresponding changes to the SIP are required. Consequently, we find 
that the California SIP revision to opt out of the federal program, as 
approved in 1999, meets the requirements of CAA sections 182(c)(4)(A) 
and 246 for Sacramento Metro Area for the 2008 ozone NAAQS.
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    \157\ 64 FR 46849 (August 27, 1999).
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4. Gasoline Vapor Recovery
    Section 182(b)(3) of the CAA requires states to submit a SIP 
revision by November 15, 1992, that requires owners or operators of 
gasoline dispensing systems to install and operate gasoline vehicle 
refueling vapor recovery (``Stage II'') systems in ozone nonattainment 
areas classified as Moderate and above. California's ozone 
nonattainment areas implemented Stage II vapor recovery well before the 
passage of the CAA Amendments of 1990.\158\
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    \158\ General Preamble, 57 FR 13498, 13514 (April 16, 1992).
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    Section 202(a)(6) of the CAA requires the EPA to promulgate 
standards requiring motor vehicles to be equipped with onboard 
refueling vapor recovery (ORVR) systems. The EPA promulgated the first 
set of ORVR system regulations in 1994 for phased implementation on 
vehicle manufacturers, and since the end of 2006, essentially all new 
gasoline-powered light and medium-duty vehicles are ORVR-equipped.\159\ 
Section 202(a)(6) also authorizes the EPA to waive the SIP requirement 
under CAA section 182(b)(3) for installation of Stage II vapor recovery 
systems after such time as the EPA determines that ORVR systems are in 
widespread use throughout the motor vehicle fleet. Effective May 16, 
2012, the EPA waived the requirement of CAA section 182(b)(3) for Stage 
II vapor recovery systems in ozone nonattainment areas regardless of 
classification.\160\ Thus, a SIP submittal meeting CAA section 
182(b)(3) is not required for the 2008 ozone NAAQS.
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    \159\ 77 FR 28772, 28774 (May 16, 2012).
    \160\ See 40 CFR 51.126(b).
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    While a SIP submittal meeting CAA section 182(b)(3) is not required 
for the 2008 ozone NAAQS, under California state law (i.e., Health and 
Safety Code section 41954), CARB is required to adopt procedures and 
performance standards for controlling gasoline emissions from gasoline 
marketing operations, including transfer and storage operations. State 
law also authorizes CARB, in cooperation with local air districts, to 
certify vapor recovery systems, to identify defective equipment and to 
develop test methods. CARB has adopted numerous revisions to its vapor 
recovery program regulations and continues to rely on its vapor 
recovery program to achieve emissions reductions in ozone nonattainment 
areas in California.
    In the Sacramento Metro Area, the installation and operation of 
CARB-certified vapor recovery equipment is required and enforced by the 
respective rules for each of the Districts, which govern gasoline 
transfer and dispensing, and organic liquid loading. Each of the 
Districts have adopted such rules, and the EPA has approved these rules 
into the SIP.\161\
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    \161\ EDCAQMD Rule 238, at 66 FR 44974 (August 27, 2001), and 
Rule 244, at 67 FR 45066 (July 8, 2002); FRAQMD Rule 3.8, at 80 FR 
38959 (July 8, 2015); PCAPCD Rule 214, at 80 FR 7345 (February 10, 
2015) and Rule 215, at 76 FR 5277 (January 31, 2011); SMAQMD Rule 
447, at 64 FR 66393 (November 26, 1999) and Rule 449, at 78 FR 897 
(January 7, 2013); and YSAQMD Rule 2.21, at 71 FR 63694 (October 31, 
2006), and Rule 2.22, at 81 FR 6763 (February 9, 2016).
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5. Enhanced Ambient Air Monitoring
    Section 182(c)(1) of the CAA requires that all ozone nonattainment 
areas classified as Serious or above implement measures to enhance and

[[Page 68532]]

improve monitoring for ambient concentrations of ozone, NOX, 
and VOC, and to improve monitoring of emissions of NOX and 
VOC. The enhanced monitoring network for ozone is referred to as the 
photochemical assessment monitoring station (PAMS) network. The EPA 
promulgated final PAMS regulations on February 12, 1993.\162\
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    \162\ 58 FR 8452 (February 12, 1993).
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    On November 10, 1993, CARB submitted to the EPA a SIP revision 
addressing the PAMS network for six ozone nonattainment areas in 
California, including the Sacramento Metro Area, to meet the enhanced 
monitoring requirements of CAA section 182(c)(1) and the PAMS 
regulations. The EPA determined that the PAMS SIP revision met all 
applicable requirements for enhanced monitoring and approved the PAMS 
submittal into the California SIP.\163\
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    \163\ 82 FR 45191 (September 28, 2017).
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    Prior to 2006, the EPA's ambient air monitoring regulations in 40 
CFR part 58 (``Ambient Air Quality Surveillance'') set forth specific 
SIP requirements (see former 40 CFR 52.20). In 2006, the EPA 
significantly revised and reorganized 40 CFR part 58.\164\ Under 
revised 40 CFR part 58, SIP revisions are no longer required; rather, 
compliance with EPA monitoring regulations is established through 
review of required annual monitoring network plans.\165\ The 2008 Ozone 
SRR made no changes to these requirements.\166\
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    \164\ 71 FR 61236 (October 17, 2006).
    \165\ 40 CFR 58.2(b) now provides that, ``The requirements 
pertaining to provisions for an air quality surveillance system in 
the SIP are contained in this part.''
    \166\ The 2008 ozone SRR addresses PAMS-related requirements at 
80 FR 12264, 12291 (March 6, 2015).
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    The Sacramento Metro Area Ozone SIP does not address specifically 
the enhanced ambient air monitoring requirement in CAA section 
182(c)(1). We note, however, that the ambient monitoring network within 
the Sacramento Metro Area is described in the SMAQMD's annual 
monitoring network plan for sites in Sacramento County and in CARB's 
annual monitoring network plan for sites outside Sacramento County, 
including those sites within the other four Sacramento Metro Area 
districts. These plans are submitted annually to the EPA, and we have 
approved both the most recent annual monitoring network plan for the 
SMAQMD (``2019 Annual Monitoring Network Plan''),\167\ as well as the 
most recent annual monitoring network plan for CARB (``Annual Network 
Plan Covering Monitoring Operations in 25 California Air Districts, 
July 2019'') with respect to the other four district's elements.\168\ 
In addition, CARB has fulfilled the requirement under 40 CFR part 58, 
Appendix D, section 5(h), to submit an Enhanced Monitoring Plan for the 
Sacramento Metro Area.\169\ Based on our review and approval of the 
SMAQMD and CARB annual monitoring network plans with respect to the 
Districts and our earlier approval of the PAMS SIP revision, we propose 
to find that CARB and the Districts meet the enhanced monitoring 
requirements under CAA section 182(c)(1) for the Sacramento Metro Area 
with respect to the 2008 ozone NAAQS.
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    \167\ Letter dated March 3, 2020, from Gwen Yoshimura, Manager, 
Air Quality Analysis Office, EPA Region IX, to Alberto Ayala, Air 
Pollution Control Officer, Sacramento Metropolitan Air Quality 
Management District.
    \168\ Letter dated November 26, 2019, from Gwen Yoshimura, 
Manager, Air Quality Analysis Office, EPA Region IX, to Ravi 
Ramalingam, Chief, Consumer Products and Air Quality Assessment 
Branch, Air Quality Planning and Science Division, CARB.
    \169\ Letter dated November 25, 2019, from Dr. Michael T. 
Benjamin, Chief, Air Quality Planning and Science Division, CARB, to 
Mr. Mike Stoker, Regional Administrator, EPA Region IX.
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6. CAA Section 185 Fee Program
    Sections 182(d)(3) and 185 of the CAA require that the SIP for each 
Severe and Extreme ozone nonattainment area provide that, if the area 
fails to attain by its applicable attainment date, each major 
stationary source of VOC and NOX located in the area shall 
pay a fee to the state as a penalty for such failure for each calendar 
year beginning after the attainment date, until the area is 
redesignated as an attainment area for ozone. States are not yet 
required to submit a SIP revision that meets the requirements of CAA 
section 185 for the 2008 ozone NAAQS.\170\
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    \170\ See 40 CFR 51.1117. For the Sacramento Metro Area, a 
section 185 SIP revision for the 2008 ozone NAAQS will be due on 
July 20, 2022.
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IV. Proposed Action

    For the reasons discussed in this document, under CAA section 
110(k)(3), the EPA is proposing to approve as a revision to the 
California SIP the following portions of the Sacramento Metro Area 
Ozone SIP, submitted by CARB on December 18, 2017 and December 5, 2018:
     Base year emissions inventory element in the 2017 
Sacramento Regional Ozone Plan as meeting the requirements of CAA 
sections 172(c)(3) and 182(a)(1) and 40 CFR 51.1115 for the 2008 ozone 
NAAQS;
     RACM demonstration element in the 2017 Sacramento Regional 
Ozone Plan as meeting the requirements of CAA section 172(c)(1) and 40 
CFR 51.1112(c) for the 2008 ozone NAAQS;
     Attainment demonstration element for the 2008 ozone NAAQS 
in the 2017 Sacramento Regional Ozone Plan as meeting the requirements 
of CAA section 182(c)(2)(A) and 40 CFR 51.1108;
     ROP demonstration element in the 2017 Sacramento Regional 
Ozone Plan as meeting the requirements of CAA 182(b)(1) and 40 CFR 
51.1110(a)(2) for the 2008 ozone NAAQS;
     RFP demonstration element in Section V--SIP Elements for 
the Sacramento Metropolitan Area of the 2018 SIP Update (as clarified) 
as meeting the requirements of CAA sections 172(c)(2), 182(b)(1), and 
182(c)(2)(B), and 40 CFR 51.1110(a)(2)(ii) for the 2008 ozone NAAQS;
     VMT emissions offset demonstration element in the 2017 
Sacramento Regional Ozone Plan as meeting the requirements of CAA 
section 182(d)(1)(A) and 40 CFR 51.1102 for the 2008 ozone NAAQS;
     Motor vehicle emissions budgets in Section V--SIP Elements 
for the Sacramento Metropolitan Area of the 2018 SIP Update for the RFP 
milestone year of 2023, and the attainment year of 2024 (see Table 9) 
because they are consistent with the RFP and attainment demonstrations 
for the 2008 ozone NAAQS proposed for approval herein and meet the 
other criteria in 40 CFR 93.118(e).
    We are also proposing to find that the:
     Emissions statement element of the 2017 Sacramento 
Regional Ozone Plan satisfies the requirements under CAA section 
182(a)(3)(B) based on our prior approval of the Districts' emission 
statement rules;
     Enhanced vehicle inspection and maintenance program in the 
Sacramento Metro Area meets the requirements of CAA section 182(c)(3) 
and 40 CFR 51.1102 for the 2008 ozone NAAQS;
     California SIP revision to opt out of the federal Clean 
Fuels Fleet Program meets the requirements of CAA sections 182(c)(4)(A) 
and 246 and 40 CFR 51.1102 for the 2008 ozone NAAQS with respect to the 
Sacramento Metro Area; and
     Enhanced monitoring in the Sacramento Metro Area meets the 
requirements of CAA section 182(c)(1) and 40 CFR 51.1102 for the 2008 
ozone NAAQS.
    Lastly, we are proposing, under CAA section 110(k)(4), to approve 
conditionally the contingency measures element of the Sacramento Metro 
Area Ozone SIP as meeting the requirements

[[Page 68533]]

of CAA sections 172(c)(9) and 182(c)(9) for RFP contingency measures. 
Our proposed approval is based on commitments by the Districts and CARB 
to supplement the element through submission, as a SIP revision (within 
one year of final conditional approval action), of new or revised 
Districts' rules that would amend or adopt specific rules with more 
stringent requirements sufficient to produce near to one year's RFP if 
an RFP milestone is not met.
    The EPA is soliciting public comments on the issues discussed in 
this proposed rule. We will accept comments from the public on this 
proposal for the next 30 days and will consider comments before taking 
final action.

V. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, the EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. 
Accordingly, this proposed action merely proposes to approve, or 
conditionally approve, state plans 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);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide the EPA with the discretionary authority 
to address disproportionate human health or environmental effects with 
practical, appropriate, and legally permissible methods under Executive 
Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where the EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction. In those areas of 
Indian country, the proposed rule does not have tribal implications and 
will not impose substantial direct costs on tribal governments or 
preempt tribal law as specified by Executive Order 13175 (65 FR 67249, 
November 9, 2000).

List of Subjects in 40 CFR Part 52

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

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

    Dated: October 10, 2020.
John Busterud,
Regional Administrator, Region IX.
[FR Doc. 2020-23032 Filed 10-28-20; 8:45 am]
BILLING CODE 6560-50-P