49100 Federal Register / Vol. 86, No. 167 / Wednesday, September 1, 2021 / Proposed Rules 

1 78 FR 3086 and 40 CFR 50.18. The EPA first 

established NAAQS for PM2.5 on July 18, 1997 (62 

FR 38652), including annual standards of 15.0 mg/ 

m3 based on a 3-year average of annual mean 

concentrations and 24-hour (daily) standards of 65 

mg/m3 based on a 3-year average of 98th percentile 

24-hour concentrations (40 CFR 50.7) (‘‘1997 PM2.5

NAAQS’’). In addition, on October 17, 2006, the 

EPA strengthened the 24-hour (daily) NAAQS for 

PM2.5 by lowering the level from 65 mg/m3 to 35 mg/ 

m3 (‘‘2006 PM2.5 NAAQS’’). 71 FR 61144 and 40 

CFR 50.13. Unless otherwise noted, all references 

to the PM2.5 standards in this notice are to the 2012 

annual NAAQS of 12.0 mg/m3 codified at 40 CFR 

50.18. 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 52 and 81 

[EPA–R09–OAR–2021–0543; FRL–8846–01– 

R9] 

Clean Air Plans; California; San 

Joaquin Valley Moderate Area Plan and 

Reclassification as Serious 

Nonattainment for the 2012 PM2.5

NAAQS; Contingency Measures for the 

2006 PM2.5 NAAQS 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) proposes to take action on 

portions of four state implementation 

plan (SIP) revisions submitted by 

California to address Clean Air Act 

(CAA or ‘‘Act’’) requirements for the 

2012 fine particulate matter (PM2.5) 

national ambient air quality standards 

(NAAQS or ‘‘standards’’) and for the 

2006 PM2.5 NAAQS in the San Joaquin 

Valley (SJV) PM2.5 nonattainment area. 

Specifically, the EPA proposes to 

approve all but the contingency measure 

element of the submitted Moderate area 

plan for the 2012 PM2.5 NAAQS, as 

updated by the submitted Serious area 

plan and related Valley State SIP 

Strategy, as meeting all applicable 

Moderate area plan requirements for the 

2012 PM2.5 NAAQS and to approve 2022 

motor vehicle emissions budgets for use 

in transportation conformity analyses 

for the 2012 PM2.5 NAAQS. The EPA 

proposes to disapprove the contingency 

measure element with respect to the 

‘‘Moderate’’ area requirements for the 

2012 PM2.5 NAAQS. The EPA also 

proposes to reclassify the SJV PM2.5

nonattainment area, including 

reservation areas of Indian country and 

any other area of Indian country within 

it where the EPA or a tribe has 

demonstrated that the tribe has 

jurisdiction, as a ‘‘Serious’’ 

nonattainment area for the 2012 PM2.5

NAAQS based on the EPA’s 

determination that the area cannot 

practicably attain the standard by the 

applicable Moderate area attainment 

date of December 31, 2021. Upon final 

reclassification of the SJV as a Serious 

area for this NAAQS, California would 

be required to submit a Serious area 

plan for the area that includes a 

demonstration of attainment by the 

applicable Serious area attainment date, 

which is no later than December 31, 

2025, or by the most expeditious 

alternative date practicable. However, 

we note that California has already 

submitted such Serious area plan that 

the EPA will address in a separate 

rulemaking. Lastly, the EPA is 

proposing to disapprove the 

contingency measure element in the 

Serious area plan for the 2006 PM2.5

NAAQS. 

DATES: Any comments on this proposal 

must be received by October 1, 2021. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R09– 

OAR–2021–0543 at https://

www.regulations.gov, or via email to 

mays.rory@epa.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. For either manner of 

submission, 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 (e.g., audio or video) must 

be accompanied by a written comment. 

The written comment is considered the 

official comment and should include 

discussion of all points you wish to 

make. The EPA will generally not 

consider comments or comment 

contents located outside of the primary 

submission (i.e., on the web, cloud, or 

other file sharing system). For 

additional submission methods, please 

contact the person identified in the FOR

FURTHER INFORMATION CONTACT section. 

For the full EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. If you need 

assistance in a language other than 

English or if you are a person with 

disabilities who needs a reasonable 

accommodation at no cost to you, please 

contact the person identified in the FOR

FURTHER INFORMATION CONTACT section. 

FOR FURTHER INFORMATION CONTACT: Rory 

Mays, Air Planning Office (AIR–2), EPA 

Region IX, by phone at (415) 972–3227 

or email at mays.rory@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document, ‘‘we,’’ ‘‘us,’’ 

or ‘‘our’’ refer to the EPA. 

Table of Contents 

I. Background for Proposed Action 

II. Summary of San Joaquin Valley 2016 and 

2018 PM2.5 Plans 

A. 2016 PM2.5 Plan Summary 

B. 2018 PM2.5 Plan Summary 

C. Procedural Requirements for SIPs and 

SIP Revisions 

III. Clean Air Act Requirements for Moderate 

PM2.5 Nonattainment Area Plans 

IV. Review of San Joaquin Valley Plans for 

Moderate Area Requirements 

A. Emissions Inventory 

B. PM2.5 Precursors 

C. Air Quality Modeling 

D. Reasonably Available Control Measures 

and Control Strategy 

E. Nonattainment New Source Review 

Requirements Under CAA Section 189(e) 

F. Demonstration That Attainment by 

Moderate Area Attainment Date Is 

Impracticable 

G. Reasonable Further Progress and 

Quantitative Milestones 

H. Contingency Measures 

I. Motor Vehicle Emissions Budgets 

V. Reclassification as Serious Nonattainment 

and Serious Area SIP Requirements 

A. Reclassification as Serious and 

Applicable Attainment Date 

B. Clean Air Act Requirements for Serious 

Area Plans 

C. Statutory Deadline for Submission of 

Serious Area Plan 

VI. Reclassification of Areas of Indian 

Country 

VII. Review of Contingency Measure Element 

for the 2006 PM2.5 NAAQS 

A. Requirements for Contingency Measures 

B. Summary of State’s Contingency 

Measure Element for 2006 PM2.5 NAAQS 

C. EPA Evaluation and Proposed Action 

VIII. Summary of Proposed Actions and 

Request for Public Comment 

IX. Statutory and Executive Order Reviews 

I. Background for Proposed Action 

On January 15, 2013, the EPA 

strengthened the primary annual 

NAAQS for particulate matter with a 

diameter of 2.5 microns or less (PM2.5) 

by lowering the level from 15.0 

micrograms per cubic meter (mg/m3) to 

12.0 mg/m3 (‘‘2012 PM2.5 NAAQS’’).1

The EPA established these standards 

after considering substantial evidence 

from numerous health studies 

demonstrating that serious health effects 

are associated with exposures to PM2.5

concentrations above these levels. 

Epidemiological studies have shown 

statistically significant correlations 

between elevated PM2.5 levels and 

premature mortality. Other important 

health effects associated with PM2.5

exposure include aggravation of 

respiratory and cardiovascular disease 

(as indicated by increased hospital 

admissions, emergency room visits, 


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2 78 FR 3086, 3088. 

3EPA, Air Quality Criteria for Particulate Matter, 

No. EPA/600/P–99/002aF and EPA/600/P–99/ 

002bF, October 2004. 

4CAA section 188(a) and 40 CFR 51.1002(a). 

5CAA section 188(c)(1) and 40 CFR 

51.1004(a)(1)(i). 

6 80 FR 2206 (codified at 40 CFR 81.305). 

7See the tables of area designations for the 1997 

and 2006 PM2.5 NAAQS in 40 CFR 81.305. 

8For a precise description of the geographic 

boundaries of the SJV PM2.5 nonattainment area, see 

40 CFR 81.305. 

9 40 CFR 51.1002(b)(1). 

10CARB submitted the two plans electronically 

on May 10, 2019, as an attachment to a letter dated 

May 9, 2019, from Richard W. Corey, Executive 

Officer, CARB, to Mike Stoker, Regional 

Administrator, EPA Region IX. 11 85 FR 44192 (July 22, 2020). 

absences from school or work, and 

restricted activity days), changes in lung 

function, and increased respiratory 

symptoms. Individuals particularly 

sensitive to PM2.5 exposure include 

older adults, people with heart and lung 

disease, and children.2 PM2.5 can be 

emitted directly into the atmosphere as 

a solid or liquid particle (‘‘primary 

PM2.5’’ or ‘‘direct PM2.5’’) or can be 

formed in the atmosphere (‘‘secondary 

PM2.5’’) as a result of various chemical 

reactions among precursor pollutants 

such as nitrogen oxides (NOX), sulfur 

oxides (SOX), volatile organic 

compounds (VOC), and ammonia 

(NH3).3

Following promulgation of a new or 

revised NAAQS, the EPA is required by 

CAA section 107(d) to designate areas 

throughout the nation as attaining or not 

attaining the NAAQS. Under subpart 4 

of part D of title I of the CAA and 

applicable implementing regulations, 

the EPA designates areas found to be 

violating the PM2.5 NAAQS, and areas 

with emissions that contribute to such 

violations, as nonattainment and 

classifies them initially as Moderate.4

States with Moderate areas have to 

attain the NAAQS as expeditiously as 

practicable, but not later than the end of 

the sixth calendar year after the date of 

designation.5 The EPA reclassifies as 

Serious those Moderate areas that 

cannot practicably attain the NAAQS by 

the latest statutory attainment date and 

those areas that fail to attain the NAAQS 

by the applicable attainment date. States 

with Serious areas are subject to more 

stringent SIP revision requirements and 

must attain the NAAQS as expeditiously 

as practicable, but not later than the end 

of the tenth calendar year after 

designation. 

On January 15, 2015, the EPA 

designated and classified the SJV as 

Moderate nonattainment for the 2012 

PM2.5 NAAQS.6 With respect to the 

1997 PM2.5 NAAQS and the 2006 PM2.5

NAAQS, the SJV is designated 

nonattainment and is classified as 

Serious.7 The SJV PM2.5 nonattainment 

area encompasses over 23,000 square 

miles and includes all or part of eight 

counties: San Joaquin, Stanislaus, 

Merced, Madera, Fresno, Tulare, Kings, 

and the valley portion of Kern.8 The 

area is home to four million people and 

is the nation’s leading agricultural 

region. Stretching over 250 miles from 

north to south and averaging 80 miles 

wide, it is partially enclosed by the 

Coast Mountain range to the west, the 

Tehachapi Mountains to the south, and 

the Sierra Nevada range to the east. 

Under State law, the San Joaquin Valley 

Unified Air Pollution Control District 

(SJVUAPCD or ‘‘District’’) has primary 

responsibility for developing plans to 

provide for attainment of the NAAQS in 

this area. The District works 

cooperatively with the California Air 

Resources Board (CARB) in preparing 

these plans. Authority for regulating 

sources under state jurisdiction in the 

SJV is split between the District, which 

has responsibility for regulating 

stationary and most area sources, and 

CARB, which has responsibility for 

regulating most mobile sources and 

some categories of consumer products. 

States with areas designated as 

nonattainment are required to submit 

SIP revisions that address various 

requirements, including the requirement 

to demonstrate attainment of the 

NAAQS as expeditiously as practicable 

but no later than the maximum 

attainment date established in the CAA 

or EPA’s implementing regulations. 

However, states with Moderate PM2.5

nonattainment areas may submit an 

impracticability demonstration, in lieu 

of a modeled attainment demonstration, 

if the state can establish that the area 

cannot practicably attain a particular 

PM2.5 NAAQS by the outermost 

statutory Moderate area attainment 

date.9

On May 10, 2019, CARB made two 

SIP submissions intended to address the 

attainment plan requirements for areas 

designated as nonattainment for the 

2012 PM2.5 NAAQS.10 First, the ‘‘2016 

Moderate Area Plan for the 2012 PM2.5

Standard’’ (‘‘2016 PM2.5 Plan’’) 

addresses the Moderate area attainment 

plan requirements and includes a 

demonstration of impracticability of 

attaining the 2012 PM2.5 NAAQS in the 

SJV by the latest permissible Moderate 

area attainment date of December 31, 

2021. In this document, the EPA is 

proposing action on all portions of the 

2016 PM2.5 Plan. Second, the ‘‘2018 Plan 

for the 1997, 2006, and 2012 PM2.5

Standards’’ (‘‘2018 PM2.5 Plan’’) 

addresses the Serious area attainment 

plan requirements for the 2012 PM2.5

NAAQS, in anticipation of the 

reclassification of SJV from Moderate to 

Serious for that PM2.5 NAAQS. The 2018 

PM2.5 Plan incorporates by reference the 

‘‘San Joaquin Valley Supplement to the 

2016 State Strategy for the State 

Implementation Plan’’ (‘‘Valley State 

SIP Strategy’’), a related plan adopted by 

CARB on October 25, 2018, and 

submitted to the EPA with the 2018 

PM2.5 Plan on May 10, 2019. For the 

purposes of this action, the relevant 

portion of the Valley State SIP Strategy 

includes the control measure 

commitments associated with the 

quantitative milestones for 2019 and 

2022. 

The 2018 PM2.5 Plan updates several 

elements in the 2016 PM2.5 Plan, 

including the base year emissions 

inventory, plan precursor 

demonstration, controls analysis, 

reasonable further progress (RFP) and 

quantitative milestones, and motor 

vehicle emission budgets (MVEBs or 

‘‘budgets’’). In this document, the EPA 

is proposing action on those portions of 

the 2018 PM2.5 Plan that apply to the 

Moderate area plan requirements for the 

2012 PM2.5 NAAQS. However, the EPA 

is not, at this time, proposing to act on 

those portions of the 2018 PM2.5 Plan 

that are not relevant to our evaluation of 

compliance with Moderate area plan 

requirements for 2012 PM2.5 NAAQS, 

such as the best available control 

measures (BACM) demonstration, 

control strategy commitments, 

attainment demonstration, RFP 

demonstration and quantitative 

milestones for later years, and MVEBs 

for later years. 

The 2018 PM2.5 Plan also addresses 

attainment plan requirements for areas 

classified as Serious for the 2006 PM2.5

NAAQS. In 2020, we approved those 

portions of the 2018 PM2.5 Plan that 

pertain to the 2006 PM2.5 NAAQS, 

excluding the contingency measures 

element for the 2006 PM2.5 NAAQS.11 In 

this document, we are proposing action 

on the portion of the 2018 PM2.5 Plan 

that addresses the contingency measure 

requirement for the 2006 PM2.5 NAAQS. 

Lastly, the 2018 PM2.5 Plan addresses 

the contingency measure requirement 

for the 2006 PM2.5 NAAQS by reference 

to, among other things, a District 

contingency measure, and emissions 

estimates for the year following the 

attainment year for use in evaluating 

whether the emissions reductions from 

the contingency measure are 


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49102 Federal Register / Vol. 86, No. 167 / Wednesday, September 1, 2021 / Proposed Rules 

12 2018 PM2.5 Plan, App. H (revised February 11, 

2020), H–24 to H–26. 

13Letter dated July 19, 2019, from Richard W. 

Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX. 

14 85 FR 44206 (July 22, 2020) (final approval of 

District Rule 4901); 85 FR 1131, 1132–33 (January 

9, 2020) (proposed approval of District Rule 4901). 

15SJVUAPCD Governing Board Resolution 16–9– 

10, September 15, 2016, and CARB Resolution 19– 

1, January 24, 2019. 

16Letter dated December 11, 2019, from Richard 

W. Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX, with 

enclosures. 

17SJVUAPCD Governing Board Resolution 18– 

11–16, November 15, 2018, and CARB Resolution 

19–1, January 24, 2019. 

18Chapter 5 (‘‘Demonstration of Federal 

Requirements for the 1997 PM2.5 Standard’’) and 

Chapter 6 (‘‘Demonstration of Federal Requirements 

for the 2006 PM2.5 Standard’’) of the 2018 PM2.5

Plan pertain to the 1997 PM2.5 NAAQS and 2006 

PM2.5 NAAQS, respectively. The EPA has acted on 

sufficient.12 With respect to the District 

contingency measure, the 2018 PM2.5

Plan calls for the District to amend 

District Rule 4901 (‘‘Wood Burning 

Fireplaces and Wood Burning Heaters’’) 

to include a requirement in the rule 

with a trigger that would activate the 

requirement should the EPA issue a 

final rulemaking that SJV failed to meet 

a regulatory requirement necessitating 

implementation of a contingency 

measure. 

In response to the commitment made 

in the 2018 PM2.5 Plan, in June 2019 the 

District adopted amendments to Rule 

4901, including a new provision 

(codified as section 5.7.3 of the 

amended rule) that is a contingency 

measure. On July 19, 2019, CARB 

submitted the amended rule to the EPA 

for approval.13 We have already taken 

final action to approve the amended 

Rule 4901 (including the new section 

5.7.3) into the California SIP, but in our 

approval we noted that we were not 

evaluating the contingency measure in 

section 5.7.3 of revised Rule 4901 for 

compliance with all requirements of the 

CAA and the EPA’s implementing 

regulations that apply to such 

measures.14 Rather, we approved the 

new provision (section 5.7.3) into the 

SIP as part of our approval of the entire 

amended rule because the provision 

strengthens the rule by providing a 

possibility of additional curtailment 

days and thus potentially additional 

emissions reductions. We indicated that 

we would evaluate whether section 

5.7.3, in conjunction with other 

submitted provisions, meets the 

statutory and regulatory requirements 

for contingency measures in a future 

action. In this document, we are 

evaluating District Rule 4901, and in 

particular section 5.7.3, in the context of 

our action on the contingency measure 

element in the 2016 PM2.5 Plan for the 

2012 PM2.5 NAAQS and the contingency 

measure element in the 2018 PM2.5 Plan 

for the 2006 PM2.5 NAAQS. 

II. Summary of San Joaquin Valley 

2016 and 2018 PM2.5 Plans 

A. 2016 PM2.5 Plan Summary 

The SJVUAPCD Governing Board 

adopted the 2016 PM2.5 Plan on 

September 15, 2016, and CARB adopted 

the plan on January 24, 2019.15 CARB 

submitted the plan to the EPA on May 

10, 2019. 

The 2016 PM2.5 Plan is organized into 

three chapters, five appendices, and two 

attachments. Chapter 1 (‘‘Introduction’’) 

provides general background, including 

discussion of the federal PM2.5

standards, PM2.5 pollution and health 

effects in the SJV, challenges to 

attaining the standards, and the 

District’s public process. Chapter 2 

(‘‘Impracticability Demonstration and 

Request for Reclassification’’) presents 

CARB and the District’s demonstration, 

based on air quality modeling, that 

attaining the 2012 PM2.5 NAAQS by the 

latest permissible attainment date of 

December 31, 2021, is impracticable, 

and a request for reclassification to 

Serious. Chapter 3 (‘‘Demonstration of 

Federal Clean Air Act Requirements’’) 

describes how the 2016 PM2.5 Plan 

addresses the federal requirements for 

Moderate PM2.5 nonattainment areas, 

including a plan precursor 

demonstration, reasonably available 

control measures, RFP, quantitative 

milestones, contingency measures, 

stationary source permitting, and 

transportation conformity. The 2016 

PM2.5 Plan includes the following five 

technical appendices: 

• Appendix A (‘‘Air Quality 

Modeling’’) provides the State’s 

photochemical air quality modeling in 

support of the plan’s impracticability 

demonstration and precursor 

demonstration; 

• Appendix B (‘‘Emissions 

Inventory’’) presents the base year and 

future year emissions inventory for 

direct PM2.5, NOX, ammonia, SOX, and 

VOC; 

• Appendix C (‘‘SIP Creditable 

Incentive-Based Emission Reductions’’) 

provides a demonstration of NOX

emission reductions from heavy-duty 

off-road vehicle engine vehicle 

replacements under the 2011 Carl 

Moyer Guidelines in support of the 

plan’s Moderate contingency measure 

element; 

• Appendix D (‘‘New Source Review 

and Emission Reduction Credits’’) 

discusses the use of emission reduction 

credits (ERCs) in the context of the plan; 

and 

• Appendix E (‘‘Summary of 

Significant Comments and Responses’’) 

summarizes significant comments 

received during the District’s 2016 

public review period and the District’s 

responses thereto. 

In addition, the 2016 PM2.5 Plan 

includes Attachment 1 (‘‘Stationary and 

Area Source Control Measure 

Analyses’’) and Attachment 2 (‘‘Mobile 

Source Control Measure Analyses’’), 

which together resubmit the State’s 

2015 analyses that the District’s 

stationary and area source control 

measures and CARB’s mobile source 

control measures represent BACM and 

most stringent measures (MSM). 

Lastly, on December 13, 2019, CARB 

submitted the following two additional 

documents that CARB had prepared for 

the 2016 PM2.5 Plan and made available 

for public review along with the plan, 

but had inadvertently omitted them 

from the May 10, 2019 SIP submission 

to the EPA: 16 (i) The ‘‘Staff Report, ARB 

Review of the San Joaquin Valley 2016 

Moderate Area Plan for the 2012 PM2.5

Standard,’’ released September 16, 2016 

(‘‘CARB 2016 Staff Report’’), that 

provides CARB’s staff review of the 

2016 PM2.5 Plan, including brief 

summaries for each of the Moderate area 

plan requirements; and (ii) the 

‘‘Modeling Emission Inventory for the 

PM2.5 State Implementation Plan in the 

San Joaquin Valley,’’ August 23, 2016 

(‘‘2016 Modeling Emissions Inventory’’) 

that describes the development of the 

2016 PM2.5 Plan’s modeling emissions 

inventory, estimation of the 2013 base 

year emissions inventory, the 

methodology used to develop the base 

year and baseline emissions inventory, 

and quality assurance of the modeling 

emissions inventory. 

B. 2018 PM2.5 Plan Summary 

The SJVUAPCD Governing Board 

adopted the 2018 PM2.5 Plan on 

November 15, 2018, and CARB adopted 

the plan on January 24, 2019.17 CARB 

submitted the 2018 PM2.5 Plan to the 

EPA on May 10, 2019, concurrently 

with the 2016 PM2.5 Plan. 

The following portions of the 2018 

PM2.5 Plan and related support 

documents apply to the Moderate area 

attainment plan requirements for the 

2012 PM2.5 NAAQS in the SJV: (i) 

Chapter 4 (‘‘Attainment Strategy for 

PM2.5’’); (ii) Chapter 7 (‘‘Demonstration 

of Federal Requirements for the 2012 

PM2.5 Standard’’); 18 (iii) numerous 


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Chapter 6 in our rulemaking for the 2006 PM2.5

NAAQS. See 80 FR 44192 (July 22, 2020). The EPA 

has proposed to act on Chapter 5 as part of a 

separate rulemaking on the 1997 annual PM2.5

NAAQS. See 86 FR 38652 (July 22, 2021). 

19The CARB 2018 Staff Report includes CARB’s 

review of, among other things, the 2018 PM2.5 Plan’s 

control strategy and attainment demonstration. 

Letter dated December 11, 2019 from Richard W. 

Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX, 

transmitting the CARB 2018 Staff Report [on the 

2018 PM2.5 Plan]. 

20CARB Resolution 19–1, ‘‘2018 PM2.5 State 

Implementation Plan for the San Joaquin Valley,’’ 

January 24, 2019, and SJVUAPCD Governing Board 

Resolution 18–11–16, ‘‘Adopting the [SJVUAPCD] 

2018 Plan for the 1997, 2006, and 2012 PM2.5

Standards,’’ November 15, 2018. 

21See D–119 to D–131. 

22SJVUAPCD, ‘‘Notice of Public Hearing, Adopt 

the Proposed 2016 Moderate Area Plan for the 2012 

PM2.5 Standard,’’ August 16, 2016, and SJVUAPCD 

Governing Board Resolution 16–9–10. 

23CARB, ‘‘Notice of Public Meeting to Consider 

the 2016 PM2.5 State Implementation Plan for the 

San Joaquin Valley,’’ September 20, 2016. 

24SJVUAPCD, ‘‘Notice of Public Hearing for 

Adoption of Proposed 2018 PM2.5 Plan for the 1997, 

2006, and 2012 Standards,’’ October 16, 2018, and 

SJVUAPCD Governing Board Resolution 18–11–16. 

25CARB, ‘‘Notice of Public Meeting to Consider 

the 2018 PM2.5 State Implementation Plan for the 

San Joaquin Valley,’’ December 21, 2018. 

26CARB Resolution 19–1. See also J&K Court 

Reporting, LLC, ‘‘Meeting, State of California Air 

Resources Board,’’ October 20, 2016 (transcript of 

CARB’s public hearing), 186–190. 

27For the 2016 PM2.5 Plan: CARB, ‘‘Board 

Meeting Comments Log,’’ available at https://

www.arb.ca.gov/lispub/comm/bccommlog.

php?listname=sjvpmplan2016 (accessed August 20, 

2021); J&K Court Reporting, LLC, ‘‘Meeting, State of 

California Air Resources Board,’’ October 16, 2016 

(transcript of CARB’s public hearing), available at 

https://ww3.arb.ca.gov/board/mt/2016/ 

mt102016.pdf (accessed December 29, 2020); and 

2016 PM2.5 Plan, App. E (‘‘Summary of Significant 

Comments and Responses’’), noting that no 

comments were received during the District’s 2016 

public review. 

28For the 2018 PM2.5 Plan: CARB, ‘‘Board 

Meeting Comments Log,’’ March 29, 2019; J&K 

Court Reporting, LLC, ‘‘Meeting, State of California 

Air Resources Board,’’ January 24, 2019 (transcript 

of CARB’s public hearing); and 2018 PM2.5 Plan, 

App. M (‘‘Summary of Significant Comments and 

Responses’’). 

29 General Preamble, 57 FR 13498 (April 16, 

1992). 

appendices to the 2018 PM2.5 Plan; (iv) 

CARB’s ‘‘Staff Report, Review of the San 

Joaquin Valley 2018 Plan for the 1997, 

2006, and 2012 PM2.5 Standards,’’ 

release date December 21, 2018 (‘‘CARB 

2018 Staff Report’’); 19 and (v) the State’s 

and District’s board resolutions 

adopting the 2018 PM2.5 Plan.20

The appendices to the 2018 PM2.5

Plan, in order of their evaluation in this 

proposal, include the following: (i) 

Appendix (‘‘App.’’) B (‘‘Emissions 

Inventory’’); (ii) a plan precursor 

demonstration and clarifications, 

including App. G (‘‘Precursor 

Demonstration’’) and Attachment A 

(‘‘Clarifying information for the San 

Joaquin Valley 2018 Plan regarding 

model sensitivity related to ammonia 

and ammonia controls’’) to the CARB 

2018 Staff Report; (iii) control strategy 

appendices, including App. C 

(‘‘Stationary Source Control Measure 

Analyses’’) and App. D (‘‘Mobile Source 

Control Measures Analyses’’); and (iv) 

App. H (‘‘RFP, Quantitative Milestones, 

and Contingency’’). The 2018 PM2.5 Plan 

addresses requirements for MVEBs in 

the ‘‘Transportation Conformity’’ 

section of App. D.21

The 2018 PM2.5 Plan also includes an 

Executive Summary, Introduction (Ch. 

1), chapters on ‘‘Air Quality Challenges 

and Trends’’ (Ch. 2) and ‘‘Health 

Impacts and Health Risk Reduction 

Strategy’’ (Ch. 3), and appendices on 

‘‘Public Education and Technology 

Advancement’’ (App. F), ‘‘Ambient 

PM2.5 Data Analysis’’ (App. A), ‘‘New 

Source Review and Emission Reduction 

Credits’’ (App. I) and ‘‘Summary of 

Significant Comments and Responses’’ 

(App. M), as well other chapters and 

appendices that are primarily relevant 

to the Serious area plan requirements, 

including App. E (‘‘Incentive-Based 

Strategy’’), App. J (‘‘Modeling Emission 

Inventory’’), App. K (‘‘Modeling 

Attainment Demonstration’’), and App. 

L (‘‘Modeling Protocol’’). 

Lastly, on February 11, 2020, CARB 

submitted, via the EPA State Planning 

Electronic Collaboration System, a 

revised version of App. H (‘‘RFP, 

Quantitative Milestones, and 

Contingency’’) that replaces the version 

submitted with the 2018 PM2.5 Plan on 

May 10, 2019. All references to App. H 

of the 2018 PM2.5 Plan in this proposed 

rule are to the revised version of 

Appendix H submitted February 11, 

2020. 

C. Procedural Requirements for SIPs 

and SIP Revisions 

Sections 110(a)(1) and (2) and 110(l) 

of the CAA require each state to provide 

reasonable public notice and an 

opportunity for a public hearing prior to 

the adoption and submittal of a SIP or 

SIP revision to the EPA. To meet this 

requirement, every SIP submission 

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. 

Both the District and CARB satisfied 

applicable statutory and regulatory 

requirements for reasonable public 

notice and hearing prior to adoption and 

submission of the 2016 PM2.5 Plan and 

the 2018 PM2.5 Plan. The District 

provided public notice and opportunity 

for public comment prior to its 

September 15, 2016 public hearing on 

and adoption of the 2016 PM2.5 Plan.22

CARB also provided public notice and 

opportunity for public comment prior to 

its October 20, 2016 public hearing,23

where the 2016 PM2.5 Plan was tabled. 

Subsequently, the District provided 

public notice and opportunity for public 

comment prior to its November 15, 2018 

public hearing on and adoption of the 

2018 PM2.5 Plan.24 CARB also provided 

public notice and opportunity for public 

comment prior to its January 24, 2019 

public hearing,25 when CARB adopted 

the 2016 PM2.5 Plan and the 2018 PM2.5

Plan.26 The SIP submission includes 

proof of publication of notices for the 

respective public hearings. It also 

includes copies of the written and oral 

comments received during the State’s 

and District’s public review processes 

and the agencies’ responses thereto.27 28

Therefore, we find that the 2016 PM2.5

Plan and the 2018 PM2.5 Plan meet the 

procedural requirements for public 

notice and hearing in CAA sections 

110(a) and 110(l) and 40 CFR 51.102. 

We present our evaluation of the 2016 

PM2.5 Plan (and 2018 PM2.5 Plan as 

applicable to the Moderate area 

attainment plan requirements for the 

2012 PM2.5 NAAQS) in Section IV of 

this proposed rule. We present our 

evaluation of the 2018 PM2.5 Plan as 

applicable to the contingency measure 

requirements for the 2006 PM2.5 NAAQS 

in section VII of this proposed rule. 

III. Clean Air Act Requirements for 

Moderate PM2.5 Nonattainment Area 

Plans 

With respect to the statutory 

requirements for particulate matter (PM) 

attainment plans, the general 

nonattainment area planning 

requirements of title I, part D of the 

CAA are found in subpart 1, and the 

attainment planning requirements 

specifically for PM are found in subpart 

4. 

The EPA has a longstanding general 

guidance document that interprets the 

1990 amendments to the CAA, 

commonly referred to as the General 

Preamble for the Implementation of 

Title I of the Clean Air Act Amendments 

of 1990 (‘‘General Preamble’’).29 The 

General Preamble addresses the 

relationship between the subpart 1 and 

subpart 4 requirements and provides 

recommendations to states for meeting 

certain statutory requirements for PM 

attainment plans. As explained in the 

General Preamble, specific requirements 

applicable to Moderate area attainment 

plan SIP submissions for the PM 

NAAQS are set forth in subpart 4 of part 


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30 Id. at 13538. 

31 59 FR 41998 (August 16, 1994). 

32 81 FR 58010 (August 24, 2016). 

33 Generally, under CAA section 188(c), the latest 

permissible attainment date for a Moderate 

nonattainment area is the end of the sixth calendar 

year after the area’s designation as nonattainment. 

Because the EPA designated and classified the San 

Joaquin Valley as a Moderate nonattainment area 

for the 2012 PM2.5 NAAQS effective April 15, 2015 

(80 FR 2206, 2217–2218), the latest permissible 

attainment date for these NAAQS in the San 

Joaquin Valley is December 31, 2021. 

34 40 CFR 51.1006 and 51.1009. 

35 40 CFR 51.1008. 

36 81 FR 58010, 58078–58079 and ‘‘Emissions 

Inventory Guidance for Implementation of Ozone 

and Particulate Matter National Ambient Air 

Quality Standards (NAAQS) and Regional Haze 

Regulations,’’ EPA, May 2017 (‘‘Emissions 

Inventory Guidance’’), available at https://

www.epa.gov/air-emissions-inventories/airemissions-inventory-guidance-implementationozone-and-particulate. 

37The Emissions Inventory Guidance identifies 

the types of sources for which the EPA expects 

states to provide condensable PM emissions 

inventories. Emissions Inventory Guidance, section 

4.2.1 (‘‘Condensable PM Emissions’’), 63–65. 

38 40 CFR 51.1008. 

39 40 CFR 51.1008(a)(1)(i). 

40The EPA released an update to AP–42 in 

January 2011 that revised the equation for 

estimating paved road dust emissions based on an 

updated data regression that included new 

emissions tests results. (76 FR 6328, February 4, 

2011). CARB used the revised 2011 AP–42 

methodology in developing on-road mobile source 

emissions. 

41AP–42 has been published since 1972 as the 

primary source of the EPA’s emission factor 

information. It contains emission factors and 

process information for more than 200 air pollution 

source categories. A source category is a specific 

industry sector or group of similar emitting sources. 

The emission factors have been developed and 

compiled from source test data, material balance 

studies, and engineering estimates. 

42The EMFAC model (short for EMission FACtor) 

is a computer model developed by CARB. The EPA 

approved and announced the availability of 

EMFAC2014 for use in SIP development and 

transportation conformity in California on 

December 14, 2015 (80 FR 77337). The EPA’s 

approval of the EMFAC2014 emissions model for 

SIP and conformity purposes was effective on the 

date of publication in the Federal Register. On 

August 15, 2019, the EPA approved and announced 

the availability of EMFAC2017, the latest update to 

the EMFAC model for use by state and local 

governments to meet CAA requirements (84 FR 

41717). EMFAC2017 was not available to the State 

and District at the time they were developing the 

2016 PM2.5 Plan and had only recently been 

submitted to the EPA on July 20, 2018, prior to the 

adoption of the 2018 PM2.5 Plan. 

43 40 CFR 51.1008(a)(2) and 51.1012(a)(2); see 

also Emissions Inventory Guidance. 

D, title I of the Act, but such SIP 

submissions must also meet the general 

attainment planning provisions in 

subpart 1 of part D, title I of the Act, to 

the extent these provisions ‘‘are not 

otherwise subsumed by, or integrally 

related to,’’ the more specific subpart 4 

requirements.30 The EPA provided 

further guidance to States on PM plan 

submissions in the Addendum to the 

General Preamble (‘‘General Preamble 

Addendum’’).31

To implement the PM2.5 NAAQS, the 

EPA has also promulgated the ‘‘Fine 

Particle Matter National Ambient Air 

Quality Standard: State Implementation 

Plan Requirements; Final Rule’’ (‘‘PM2.5

SIP Requirements Rule’’).32 The PM2.5

SIP Requirements Rule establishes 

regulatory requirements and provides 

additional guidance applicable to 

attainment plan submissions for the 

PM2.5 NAAQS, including the 2012 

annual PM2.5 NAAQS and the 2006 24- 

hour PM2.5 NAAQS, addressed in this 

section and section VII, respectively, of 

this proposed rule. 

The general subpart 1 statutory 

requirements for attainment plans 

include the following: (i) The section 

172(c)(1) requirement for reasonably 

available control measures (RACM)/ 

reasonably available control technology 

(RACT) and attainment demonstrations; 

(ii) the section 172(c)(2) requirement to 

RFP; (iii) the section 172(c)(3) 

requirement for emissions inventories; 

(iv) the section 172(c)(5) requirement for 

a nonattainment new source review 

(NNSR) permitting program; and (v) the 

section 172(c)(9) requirement for 

contingency measures. 

The more specific subpart 4 statutory 

requirements for Moderate PM2.5

nonattainment areas include the 

following: (i) The section 189(a)(1)(A) 

and 189(e) NNSR permit program 

requirements; (ii) the section 

189(a)(1)(B) requirement for attainment 

demonstrations; (iii) the section 

189(a)(1)(C) requirement for RACM; and 

(iv) the section 189(c) requirements for 

RFP and quantitative milestones. Under 

subpart 4, states with Moderate PM2.5

nonattainment areas must provide for 

attainment in the area as expeditiously 

as practicable but no later than the latest 

permissible attainment date under CAA 

section 188(c), i.e., December 31, 2021, 

for the 2012 PM2.5 NAAQS in the SJV, 

unless the EPA determines, per section 

188(b)(1), that the area cannot 

practicably attain the NAAQS by the 

Moderate area attainment date.33 In 

addition, under subpart 4, direct PM2.5

and all precursors to the formation of 

PM2.5 are subject to control unless the 

EPA approves a demonstration from the 

state establishing that a given precursor 

does not contribute significantly to 

PM2.5 levels that exceed the PM2.5

NAAQS in the area.34

IV. Review of San Joaquin Valley Plans 

for Moderate Area Requirements 

A. Emissions Inventory 

1. Requirements for Emissions 

Inventories 

Section 172(c)(3) of the CAA requires 

that each SIP include a comprehensive, 

accurate, current inventory of actual 

emissions from all sources of the 

relevant pollutant or pollutants in the 

nonattainment area. We refer to this 

inventory as the ‘‘base year inventory.’’ 

The EPA has established regulatory 

requirements for base year and other 

emissions inventories in the PM2.5 SIP 

Requirements Rule 35 and issued 

guidance concerning emissions 

inventories for PM2.5 nonattainment 

areas.36

The base year emissions inventory 

should provide a state’s best estimate of 

actual emissions from all sources of the 

relevant pollutants in the area, i.e., all 

emissions that contribute to the 

formation of a particular NAAQS 

pollutant. For the PM2.5 NAAQS, the 

base year emissions inventory must 

include direct PM2.5 emissions, 

separately reported filterable and 

condensable PM2.5 emissions,37 and 

emissions of all chemical precursors to 

the formation of secondary PM2.5: NOX, 

SO2, VOC, and ammonia.38 In addition, 

the emissions inventory base year for a 

Moderate PM2.5 nonattainment area 

must be one of the three years (i.e., 

2011–2013) for which monitored data 

were used to designate the area as 

nonattainment, or another technically 

appropriate year justified by the state in 

its Moderate area attainment plan 

submission.39

In its SIP submission, a state must 

include documentation explaining how 

it calculated emissions data. In 

estimating mobile source emissions, a 

state should use the latest emissions 

models and planning assumptions 

available at the time it develops the SIP 

submission. States are also required to 

use the EPA’s ‘‘Compilation of Air 

Pollutant Emission Factors’’ (‘‘AP–42’’) 

road dust method for calculating reentrained road dust emissions from 

paved roads.40 41 At the time the 2016 

PM2.5 Plan and 2018 PM2.5 Plan were 

developed, California was required to 

use EMFAC2014 to estimate tailpipe 

and brake and tire wear emissions of 

PM2.5, NOX, SO2, and VOC from on-road 

mobile sources.42

In addition to the base year inventory 

submitted to meet the requirements of 

CAA section 172(c)(3), a state must also 

submit future ‘‘baseline inventories’’ for 

the projected attainment year, each RFP 

milestone year, and any other year of 

significance for meeting applicable CAA 

requirements.43 By baseline inventories 

we mean projected emissions 

inventories for future years that account 

for, among other things, the ongoing 


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44The 2016 PM2.5 Plan generally uses ‘‘sulfur 

oxides’’ or ‘‘SOX’’ in reference to SO2 as a precursor 

to the formation of PM2.5. We use SOX and SO2

interchangeably throughout this notice. 

45 2016 PM2.5 Plan, App. B, B–18. 

46The 2016 PM2.5 Plan includes annual average 

and winter day average inventories for PM2.5

planning purposes. The winter average daily 

planning inventory corresponds to the months of 

November through April, when daily, ambient 

PM2.5 concentrations are typically highest. 2016 

PM2.5 Plan, App. B, B–19. The base year inventory 

is from the California Emissions Inventory 

Development and Reporting System (CEIDARS) and 

future year inventories were estimated using the 

California Emission Projection Analysis Model 

(CEPAM) version 1.04. 

47 2018 PM2.5 Plan, App. B, B–18. 

48 2018 PM2.5 Plan, App. B, B–19. The base year 

inventory is from CEIDARS and future year 

inventories were estimated using CEPAM, version 

1.05. 

49 2016 PM2.5 Plan, App. B, section B.3 

(‘‘Emissions Inventory Summary and 

Methodology’’), and 2018 PM2.5 Plan, App. B, 

section B.2 (‘‘Emissions Inventory Summary and 

Methodology’’). 

50For example, paved road dust direct PM2.5

emissions decreased 0.1 tpd while off-road 

equipment NOX emissions increased by 0.1 tpd 

between the 2016 and 2018 PM2.5 Plans. 

51 2018 PM2.5 Plan, App. B, B–26. 

52 2018 PM2.5 Plan, App. B, B–27. 

53 2018 PM2.5 Plan, App. B, B–34. 

54 2018 PM2.5 Plan, App. B, B–42 to B–44. The 

EPA has approved the emissions inventory 

submission for the 2006 PM2.5 NAAQS in the SJV, 

including the filterable and condensable PM2.5

inventories. 85 FR 44192 (July 22, 2020) (final rule); 

and 85 FR 17382, 17389 (March 27, 2020) (proposed 

rule). 

55 2016 PM2.5 Plan, App. B, B–33; and 2018 PM2.5

Plan, App. B, B–37. We note that the vehicle miles 

traveled data used in the 2018 PM2.5 Plan’s 

emissions inventory is from the final 2017 Federal 

Transportation Improvement Program from each of 

the SJV’s eight metropolitan planning organizations. 

56 2016 PM2.5 Plan, App. B, B–26; and 2018 PM2.5

Plan, App. B, B–28. 

57 2016 PM2.5 Plan, App. B, B–33 through B–35; 

and 2018 PM2.5 Plan, App. B, B–38 through B–40. 

58 2016 PM2.5 Plan, App. B, B–19; and 2018 PM2.5

Plan, App. B, B–19. 

59 2016 PM2.5 Plan, App. D, D–1 through D–5; and 

2018 PM2.5 Plan, App. I, I–1 through I–5. 

effects of economic growth and adopted 

emission control requirements. The SIP 

submission should include 

documentation to explain how the state 

calculated the emissions projections. 

2. Summary of State’s Emissions 

Inventories 

Within the 2016 PM2.5 Plan, the 

annual average planning inventories for 

direct PM2.5 and all PM2.5 precursors 

(NOX, ammonia, SOX,44 and VOC) for 

the SJV PM2.5 nonattainment area, 

together with documentation for the 

inventories, are found in Appendix B 

(‘‘Emissions Inventory’’). In addition, 

Appendix A (‘‘Air Quality Modeling’’) 

contains inventory documentation 

specific to the air quality modeling 

inventories. These portions of the 2016 

PM2.5 Plan contain annual average daily 

emission inventories for 2013 thru 2022 

projected from the 2012 actual 

emissions inventory,45 including the 

2013 base year, the 2019 RFP baseline 

year, the 2021 Moderate area attainment 

year, and the 2022 post-attainment RFP 

year. The winter average daily inventory 

is used to evaluate sources of emissions 

for attainment of the 2012 PM2.5 NAAQS 

in the 2016 PM2.5 Plan.46

Similarly, within the 2018 PM2.5 Plan, 

the annual average planning inventories 

for direct PM2.5 and all PM2.5 precursors, 

together with documentation for the 

inventories, are found in Appendix B 

(‘‘Emissions Inventory’’). In addition, 

Appendix J (‘‘Modeling Emission 

Inventory’’) contains inventory 

documentation specific to the air quality 

modeling inventories. These portions of 

the 2018 PM2.5 Plan contain annual 

average daily emission inventories for 

2013 thru 2028 projected from the 2012 

actual emissions inventory, 47 including 

the 2013 base year, the 2019 and 2022 

RFP baseline years, the 2025 Serious 

area attainment year, and the 2028 postattainment RFP year. Both the annual 

average and the winter average daily 

inventories are used to evaluate sources 

of emissions for attainment of the 2012 

PM2.5 NAAQS in the 2018 PM2.5 Plan.48

The base year inventories for 

stationary sources were developed using 

actual emissions reports made by 

facility operators. The State developed 

the base year emissions inventories for 

area sources using the most recent 

models and methodologies available at 

the time the State was developing the 

2016 PM2.5 Plan and 2018 PM2.5 Plan.49

Importantly, CARB and the District 

updated the emissions inventory in the 

2018 PM2.5 Plan using the latest 

available activity data and emission 

methodologies available at the time of 

plan development. The 2013 base year, 

annual average emissions inventories 

for most source categories did not 

change or only changed plus or minus 

0.1 tons per day (tpd) between the two 

plans.50 However, the base year 

emissions inventory from several 

important source categories were 

smaller in the 2018 PM2.5 Plan relative 

to the 2016 PM2.5 Plan based on the 

latest information. These include a 1.2 

tpd decrease in direct PM2.5 emissions 

from residential fuel combustion based 

on a 2016 emissions inventory 

methodology update,51 a 0.4 tpd 

decrease in direct PM2.5 emissions from 

farming operations based on updated 

estimates by the California Department 

of Conservation of harvested acreage in 

2010–2020 rather than 2000–2009,52

and a 0.9 tpd decrease in NOX emissions 

from trains based on updated 

locomotive data from 2016 on Class I 

and Class II railroads.53 Overall, for the 

2013 base year, total emissions of both 

direct PM2.5 and NOX were 0.9 tpd 

smaller in the 2018 PM2.5 Plan relative 

to the 2016 PM2.5 Plan. 

Furthermore, the 2016 PM2.5 Plan’s 

emissions inventory does not separately 

report filterable and condensable PM2.5

emissions. However, the 2018 PM2.5

Plan includes background, 

methodology, and inventories of 

condensable and filterable PM2.5

emissions from stationary point and 

non-point combustion sources that are 

expected to generate condensable 

PM2.5.54 It provides filterable and 

condensable emissions estimates, 

expressed as annual PM2.5 emissions 

(tons per year), for all of the identified 

source categories for the years 

applicable to the Moderate area 

timeframe, including the 2013 base year, 

the 2019 RFP year, the 2021 Moderate 

area attainment year, and the 2022 postattainment RFP year, as well as 

subsequent years. 

CARB used EMFAC2014 to estimate 

on-road motor vehicle emissions based 

on transportation activity data from the 

2014 Regional Transportation Plan 

adopted by the transportation planning 

agencies in the SJV.55 Re-entrained 

paved road dust emissions were 

calculated using a CARB methodology 

consistent with the EPA’s AP–42 road 

dust methodology.56 CARB also 

provided emissions inventories for offroad equipment, including aircraft, 

trains, recreational boats, construction 

equipment, and farming equipment, 

among others. CARB uses a suite of 

category-specific models to estimate offroad emissions for many categories and, 

where a new model was not available, 

used the OFFROAD2007 model.57

CARB developed the emissions 

forecasts by applying growth and 

control profiles to the base year 

inventory. CARB’s mobile source 

emissions projections take into account 

predicted activity rates and vehicle fleet 

turnover by vehicle model year and 

adopted controls.58 In the 2016 PM2.5

Plan and 2018 PM2.5 Plan, the District 

provides for use of pre-base year ERCs 

as offsets by accounting for such ERCs 

in the projected emissions inventory for 

the 2022 RFP year and the projected 

2025 attainment year, respectively.59

The plans identify growth factors, 

control factors, and estimated offset use 

between 2013 and 2022, and between 

2013 and 2025, for direct PM2.5, NOX, 

SOX, and VOC emissions by source 

category and lists all pre-base year ERCs 


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60Particulate matter with a diameter of 10 

microns or less. 

61 2016 PM2.5 Plan, App. D, tables D–1 through D– 

5; and 2018 PM2.5 Plan, App. I, tables I–1 through 

I–5. 

62 2016 PM2.5 Plan, Table 3–2. This includes 

District rules for open burning; boilers, steam 

generators, and process heaters; flares; glass melting 

furnaces; stationary internal combustion engines; 

and residential wood burning. 

63EPA, ‘‘Technical Support Document, General 

Evaluation, San Joaquin Valley PM2.5 Plan for the 

2006 PM2.5 NAAQS,’’ February 2020 (‘‘EPA’s 

General Evaluation TSD’’). Table V–A of EPA’s 

General Evaluation TSD shows District rules with 

post-2013 compliance dates that are reflected in the 

future year baseline inventories of the 2018 PM2.5

Plan, along with information on the EPA’s approval 

of these rules. 

issued by the District for PM10,60 NOX, 

SOX, and VOC emissions, by facility.61

Table 1 provides a summary of the 

2018 PM2.5 Plan’s winter (24-hour) 

average inventories in tpd of direct 

PM2.5 and PM2.5 precursor emissions for 

the 2013 base year. Table 2 provides a 

summary of 2018 PM2.5 Plan’s annual 

average inventories of direct PM2.5 and 

PM2.5 precursor emissions for the 2013 

base year. For purposes of this proposal, 

these annual average inventories 

provide bases primarily for our 

evaluation of the precursor 

demonstration, control measure 

analysis, impracticability 

demonstration, RFP demonstration, and 

MVEBs in the 2018 PM2.5 Plan with 

respect the Moderate area requirements. 

TABLE 1—SAN JOAQUIN VALLEY WINTER AVERAGE EMISSIONS INVENTORY FOR DIRECT PM2.5 AND PM2.5 PRECURSORS

FOR THE 2013 BASE YEAR

[tpd] 

Category Direct PM2.5 NOX SOX VOC Ammonia 

Stationary Sources ............................................................... 8.5 35.0 6.9 86.6 13.9 

Area Sources ....................................................................... 41.4 11.5 0.5 156.8 291.5 

On-Road Mobile Sources .................................................... 6.4 188.7 0.6 51.1 4.4 

Non-Road Mobile Sources ................................................... 4.4 65.3 0.3 27.4 0.0 

Totals a .......................................................................... 60.8 300.5 8.4 321.9 309.8 

Source: 2018 PM2.5 Plan, Appendix B, tables B–1 through B–5. aTotals reflect disaggregated emissions and may not add exactly as shown here due to rounding. 

TABLE 2—SAN JOAQUIN VALLEY ANNUAL AVERAGE EMISSIONS INVENTORY FOR DIRECT PM2.5 AND PM2.5 PRECURSORS

FOR THE 2013 BASE YEAR

[tpd] 

Category Direct PM2.5 NOX SOX VOC Ammonia 

Stationary Sources ............................................................... 8.8 38.6 7.2 87.1 13.9 

Area Sources ....................................................................... 41.5 8.1 0.3 153.4 310.9 

On-Road Mobile Sources .................................................... 6.4 183.1 0.6 49.8 4.4 

Non-Road Mobile Sources ................................................... 5.8 87.4 0.3 33.8 0.0 

Totals a .......................................................................... 62.5 317.2 8.5 324.1 329.2 

Source: 2018 PM2.5 Plan, Appendix B, tables B–1 through B–5. aTotals reflect disaggregated emissions and may not add exactly as shown here due to rounding. 

3. EPA Evaluation and Proposed Action 

Consistent with the requirement that 

inventories be based on the most current 

and accurate information available to 

the State and District at the time they 

were developing the plans and 

inventories, our evaluation for the SJV 

for the 2012 PM2.5 NAAQS relies 

primarily on the emissions inventories 

in the 2018 PM2.5 Plan. The inventories 

in the 2018 PM2.5 Plan include the latest 

version of California’s mobile source 

emissions model, EMFAC2014, that had 

been approved by the EPA at the time, 

and the EPA’s most recent AP–42 

methodology for paved road dust. The 

inventories comprehensively address all 

source categories in the SJV PM2.5

nonattainment area and are consistent 

with the EPA’s inventory guidance. 

In accordance with 40 CFR 

51.1008(a), the 2013 base year is one of 

the three years for which monitored 

data were used for designating the area, 

and it represents annual average 

emissions of all sources within the 

nonattainment area. Direct PM2.5 and 

PM2.5 precursors are included in the 

inventories, and filterable and 

condensable direct PM2.5 emissions are 

identified separately. 

With respect to future year baseline 

projections, we have reviewed the 

growth and control factors and find 

them acceptable and thus conclude that 

the future baseline emissions 

projections in the 2016 PM2.5 Plan and 

2018 PM2.5 Plan reflect appropriate 

calculation methods and the latest 

planning assumptions at the time the 

State and District were developing the 

plans and inventories. Also, as a general 

matter, the EPA will approve a SIP 

submission that takes emissions 

reduction credit for a control measure 

only where the EPA has approved the 

measure as part of the SIP. Thus, for 

example, to take credit for the emissions 

reductions from newly adopted or 

amended District rules for stationary 

and area sources, the related rules must 

be approved by the EPA into the SIP. 

Given the State’s impracticability 

demonstration for attaining the 2012 

PM2.5 NAAQS in the SJV by the 

outermost Moderate area attainment 

date, the 2016 PM2.5 Plan describes the 

District rules achieving post-2013 

emission reductions that contribute 

towards attaining the NAAQS.62 In our 

rulemaking on the State’s attainment 

plan for the 2006 PM2.5 NAAQS in the 

SJV, we reviewed the baseline measures 

identified as 2018 PM2.5 Plan baseline 

controls to ensure that the measures that 

are relied upon in the plan have been 

submitted and approved as part of the 

California SIP.63 That set of 2018 PM2.5

Plan baseline measures includes all 


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64See, e.g., 81 FR 39424 (June 16, 2016), 82 FR 

14447 (March 21, 2017), and 83 FR 23232 (May 18, 

2018). 

65The baseline emissions projections in the 2016 

PM2.5 Plan assume implementation of CARB’s zero 

emissions vehicle (ZEV) sales mandate and 

greenhouse gas (GHG) standards, based on the 

approved EMFAC2014 model and assumptions that 

were available at the time of the SIP’s development. 

On September 27, 2019, the U.S. Department of 

Transportation and the EPA (the Agencies) issued 

a notice of final rulemaking for the ‘‘Safer 

Affordable Fuel-Efficient (SAFE) Vehicles Rule Part 

One: One National Program’’ (‘‘SAFE I’’) that, 

among other things, withdrew the EPA’s 2013 

waiver of preemption of CARB’s ZEV sales mandate 

and vehicle GHG standards. 84 FR 51310 

(September 27, 2019). See also proposed SAFE rule 

at 83 FR 42986 (August 24, 2018). In response to 

SAFE I, CARB developed EMFAC off-model 

adjustment factors to account for anticipated 

changes in on-road emissions. On March 12, 2020, 

the EPA informed CARB that the EPA considers 

these adjustment factors to be acceptable for future 

use. See letter dated March 12, 2020, from Elizabeth 

J. Adams, EPA Region IX, to Steven Cliff, CARB. On 

April 30, 2020 (85 FR 24174), the Agencies issued 

a notice of final rulemaking for the ‘‘The Safer 

Affordable Fuel-Efficient (SAFE) Vehicles Rule for 

Model Years 2021–2026 Passenger Cars and Light 

Trucks’’ (‘‘SAFE II’’), establishing the federal fuel 

economy and GHG vehicle emissions standards 

based on the August 2018 SAFE proposal. The 

effect of both SAFE final rules (SAFE I and SAFE 

II) on the on-road vehicle mix in the SJV 

nonattainment area and on the resulting vehicular 

emissions is expected to be minimal during the 

timeframe addressed in this SIP revision. Therefore, 

we anticipate the SAFE final rules would not 

materially change the demonstration that it is 

impracticable for the SJV 2012 PM2.5 Moderate area 

to attain by the Moderate area attainment date of 

December 31, 2021. 

66 General Preamble, 13539–13542. 

67Courts have upheld this approach to the 

requirements of subpart 4 for PM10. See, e.g., Assoc. 

of Irritated Residents v. EPA, et al., 423 F.3d 989 

(9th Cir. 2005). 

68 40 CFR 51.1006(a)(1). 

69 Id. 

those baseline measures identified in 

the 2016 PM2.5 Plan’s RFP 

demonstration as achieving emission 

reductions post-2013. Based on that 

review, we confirm that the stationary 

and area source baseline measures in 

the 2016 PM2.5 Plan and 2018 PM2.5

Plan are approved into the SIP and 

support the emissions reductions for 

future years in the SJV. With respect to 

mobile sources, the EPA has acted in 

recent years to approve CARB mobile 

source regulations into the state-wide 

portion of the California SIP.64 We 

therefore find that the future year 

baseline projections in the 2016 PM2.5

Plan and 2018 PM2.5 Plan are properly 

supported by SIP-approved stationary, 

area, and mobile source measures.65

For these reasons, we are proposing to 

approve the 2013 base year emissions 

inventory in the 2018 PM2.5 Plan as 

meeting the requirements of CAA 

section 172(c)(3) and 40 CFR 51.1008. 

We are also proposing to find that the 

future year baseline inventories in the 

2016 PM2.5 Plan and 2018 PM2.5 Plan 

satisfy the requirements of 40 CFR 

51.1008(a)(2) and 51.1012(a)(2) and 

provide an adequate basis for the 

control measure, RFP, and 

impracticability demonstrations in the 

2016 PM2.5 Plan and 2018 PM2.5 Plan, 

respectively. 

B. PM2.5 Precursors 

1. Requirements for Control of PM2.5

Precursors 

The provisions of subpart 4 of part D, 

title I of the CAA do not define the term 

‘‘precursor’’ for purposes of PM2.5, nor 

do they explicitly require the control of 

any specifically identified PM 

precursor. The statutory definition of 

‘‘air pollutant’’ in CAA section 302(g), 

however, provides that the term 

‘‘includes any precursors to the 

formation of any air pollutant, to the 

extent the Administrator has identified 

such precursor or precursors for the 

particular purpose for which the term 

‘air pollutant’ is used.’’ The EPA has 

identified NOX, SO2, VOC, and 

ammonia as precursors to the formation 

of PM2.5. Accordingly, the attainment 

plan requirements of subpart 4 apply to 

emissions of all four precursor 

pollutants and direct PM2.5 from all 

types of stationary, area, and mobile 

sources, except as otherwise provided in 

the Act (e.g., in CAA section 189(e)). 

Section 189(e) of the Act requires that 

the control requirements for major 

stationary sources of direct PM10 (which 

includes PM2.5) also apply to major 

stationary sources of PM10 precursors, 

except where the Administrator 

determines that such sources do not 

contribute significantly to PM10 levels 

that exceed the standard in the area. 

Section 189(e) contains the only express 

exception to the control requirements 

under subpart 4 (e.g., requirements for 

RACM, RACT, BACM, best available 

control technology (BACT), MSM, and 

NNSR) for sources of direct PM2.5 and 

PM2.5 precursor emissions. Although 

section 189(e) explicitly addresses only 

major stationary sources, the EPA 

interprets the Act as authorizing it also 

to determine, under appropriate 

circumstances, that regulation of 

specific PM2.5 precursors from other 

source categories in a given 

nonattainment area is not necessary. For 

example, under the EPA’s longstanding 

interpretation of the control 

requirements that apply to stationary 

and mobile sources of PM10 precursors 

in the nonattainment area under CAA 

section 172(c)(1) and subpart 4,66 a state 

may demonstrate in a SIP submission 

that control of a certain precursor 

pollutant is not necessary in light of its 

insignificant contribution to ambient 

PM10 levels in the nonattainment area.67

Under the PM2.5 SIP Requirements 

Rule, a state may elect to submit to the 

EPA a ‘‘comprehensive precursor 

demonstration’’ for a specific 

nonattainment area to show that 

emissions of a particular precursor from 

all existing sources located in the 

nonattainment area do not contribute 

significantly to PM2.5 levels that exceed 

the standard in the area.68 If the EPA 

determines that the contribution of the 

precursor to PM2.5 levels in the area is 

not significant and approves the 

demonstration, the state is not required 

to control emissions of the relevant 

precursor from existing sources in the 

attainment plan.69

We are evaluating the 2016 PM2.5 Plan 

and 2018 PM2.5 Plan with respect to the 

Moderate area requirements in 

accordance with the presumption 

embodied within subpart 4 that all 

PM2.5 precursors must be addressed in 

the State’s evaluation of potential 

control measures, unless the State 

adequately demonstrates that emissions 

of a particular precursor or precursors 

do not contribute significantly to 

ambient PM2.5 levels that exceed the 

PM2.5 NAAQS in the nonattainment 

area. In reviewing any determination by 

the State to exclude a PM2.5 precursor 

from the required evaluation of 

potential control measures, we consider 

both the magnitude of the precursor’s 

contribution to ambient PM2.5

concentrations in the nonattainment 

area and the sensitivity of ambient PM2.5

concentrations in the area to reductions 

in emissions of that precursor. 

2. Summary of State’s Precursor 

Demonstrations 

The State presents analyses of PM2.5

precursors in both the 2016 PM2.5 Plan 

and the 2018 PM2.5 Plan and primarily 

relies on sensitivity-based contribution 

analyses to determine whether each 

PM2.5 plan precursor contributes 

significantly to ambient PM2.5 levels that 

exceed the 2012 PM2.5 NAAQS. We 

summarize below key points from the 

State’s analyses and conclusions for 

each pollutant, focusing on the three 

precursors (ammonia, SOX, and VOC) 

that the State concludes do not 

contribute significantly to PM2.5 levels 

that exceed the 2012 PM2.5 NAAQS in 

the SJV. 

In the 2016 PM2.5 Plan, the State’s 

precursor demonstration and 

conclusions are found in section 2.3 

(‘‘Summary of Modeling Results’’), 

section 3.3 (‘‘Precursor 


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70 2016 PM2.5 Plan, 2–4 and Table 2–1. 

71 Id. at Table 2–4. 

72Using the species assignments recommended in 

the Draft Precursor Demonstration Guidance (on 

page 21) the relevant concentrations are as follows: 

For NOX, the nitrate and associated ammonium is 

up to 7.1 mg/m3; for SO2, sulfate is up to 1.7 mg/ 

m3; for ammonia, the sum of ammonium and nitrate 

is up to 7.1 mg/m3; for VOC the only available 

concentration is for ‘‘OM’’ (organic matter), which 

is up to 8.7 mg/m3, and is likely much higher than 

the secondary organic aerosol that is relevant for 

VOC as a PM2.5 precursor. All these values are well 

above the 0.2 mg/m3 threshold. 

73 2016 PM2.5 Plan, App. A, section 5.4 

(‘‘Precursor Sensitivity Analysis’’). 

74For the annual PM2.5 NAAQS, the EPA 

generally expects that a precursor demonstration 

showing that the air quality impact of a given 

precursor at all relevant locations does not exceed 

a contribution threshold of 0.2 mg/m3 will be 

adequate to exempt sources of that precursor from 

control requirements. PM2.5 Precursor Guidance, 17. 

75 2016 PM2.5 Plan, App. A, tables 24, 26, 28, and 

27, respectively. 

76 Id. at 2–6 and 3–3, and App. A, A–52. We note 

that direct PM2.5 emissions are considered a 

primary source of ambient PM2.5 (i.e., no further 

formation in the atmosphere is required), and 

therefore is not considered a precursor pollutant 

under subpart 4, which may differ from a more 

generalized understanding of what contributes to 

ambient PM2.5. 

77Letter dated May 9, 2019, from Richard W. 

Corey, Executive Officer, CARB, to Michael Stoker, 

Regional Administrator, EPA Region IX, 

Attachment A (‘‘Clarifying information for the San 

Joaquin Valley 2018 Plan regarding model 

sensitivity related to ammonia and ammonia 

controls’’). 

78Email dated June 20, 2019, ‘‘RE: SJV model 

disbenefit from SOX reduction,’’ from Jeremy Avise, 

CARB, to Scott Bohning, EPA Region IX, with 

attachment (‘‘CARB’s June 2019 Precursor 

Clarification’’); email dated September 19, 2019, 

‘‘FW: SJV species responses,’’ from Jeremy Avise, 

CARB, to Scott Bohning, EPA Region IX, with 

attachments (‘‘CARB’s September 2019 Precursor 

Clarification’’); email dated October 18, 2019, from 

Laura Carr, CARB to Scott Bohning, Jeanhee Hong, 

and Rory Mays, EPA Region IX, with attachment 

‘‘Clarifying Information on Ammonia’’ (‘‘CARB’s 

October 2019 Precursor Clarification’’); and email 

dated April 26, 2021, from Laura Carr, CARB, to 

Scott Bohning, EPA Region IX, Subject: ‘‘RE: 

Ammonia update,’’ with attachment ‘‘Ammonia in 

San Joaquin Valley’’ (‘‘CARB’s April 26, 2021, 

Precursor Clarification’’). 

79 2018 PM2.5 Plan, Ch. 7, 7–5 and Table 7–2. 

Notably, the estimated 64% reduction in NOX from 

2013 to 2025 (per the 2018 PM2.5 Plan) is much 

larger than the estimated 38% reduction in NOX

from 2013 to 2021 (per the 2016 PM2.5 Plan), 

reflecting both additional years of reductions and 

additional reductions anticipated from the 2018 

PM2.5 Plan control strategy. We also note that a copy 

of the contents of the 2018 PM2.5 Plan, App. G 

appears in the CARB 2018 Staff Report, App. C4 

(‘‘Precursor Demonstrations for Ammonia, SOX, and 

ROG’’). 

80 ‘‘PM2.5 Precursor Demonstration Guidance, 

Draft for Public Review and Comments,’’ EPA–454/ 

P–16–001, November 17, 2016, including Memo 

dated November 17, 2016 from Stephen D. Page, 

Director, OAQPS, EPA to Regional Air Division 

Directors, Regions 1–10, EPA. 

81 2018 PM2.5 Plan, App. G, 3. The 2018 PM2.5

Plan presents a graphical representation of annual 

average ambient PM2.5 components (i.e., crustal 

particulate matter, elemental carbon, organic 

matter, ammonium sulfate, and ammonium nitrate) 

for 2011–2013 for Bakersfield, Fresno, and Modesto. 

2018 PM2.5 Plan, Ch. 3, 3–3 to 3–4. 

82 2018 PM2.5 Plan, Ch. 7, 7–7. The sensitivitybased analysis used the same modeling platform as 

that used for the 2018 PM2.5 Plan’s attainment and 

RFP demonstrations. CARB modeled the impacts of 

both NOX reductions and direct PM2.5 reductions, 

but the direct PM2.5 results were used only as a 

point of comparison, as direct PM2.5 emissions must 

be regulated in all PM2.5 nonattainment areas. 

Demonstration’’), and Appendix A (‘‘Air 

Quality Modeling’’). The State estimates 

that baseline anthropogenic emissions 

of NOX, ammonia, SOX, and VOC will 

decrease by 38 percent (%), 1%, 2%, 

and 8%, respectively, between 2013 and 

2021.70 The State does not present a 

concentration-based analysis of the 

contribution of each precursor to 

ambient PM2.5 concentrations, but does 

estimate PM2.5 component 

concentrations in the 2013 base year 

across all SJV monitoring sites.71 The 

concentrations indicate that each 

precursor may have a significant impact 

on PM2.5 levels.72 The State presents a 

sensitivity-based precursor analysis 

using the modeled response of ambient 

PM2.5 concentrations to a 15% increase 

or decrease in the future baseline 

emissions of each precursor in 2025 (the 

latest permissible attainment year if the 

area is reclassified to Serious for the 

2012 PM2.5 NAAQS).73 For each 

precursor, the State then takes the 

difference between the PM2.5

concentrations from the 15% increase 

and the 15% decrease to estimate the 

ambient PM2.5 response to a 30% change 

in the precursor, and reviews the 

resulting change at each monitor to see 

whether any response exceeds a 

threshold of 0.2 mg/m3.74

The responses range from 0.5 mg/m3 to 

1.5 mg/m3 for NOX; from 0.1 mg/m3 to 0.2 

mg/m3 for ammonia; from 0.1 mg/m3 to 

0.2 mg/m3 for SOX; and from –0.1 mg/m3

to 0.1 mg/m3 for VOC.75 The State 

concludes that emissions of NOX (as 

well as direct PM2.5) contribute 

significantly to ambient PM2.5 levels that 

exceed the PM2.5 NAAQS but ammonia, 

SOX, and VOC do not contribute 

significantly to such exceedances.76 The 

2016 PM2.5 Plan, Appendix A, section 

5.5 (‘‘Discussion of Precursor 

Sensitivity’’) includes additional 

discussion of ammonia’s and VOC’s role 

in the formation of ammonium nitrate 

and VOC’s role in the formation of 

secondary organic aerosols. 

In the 2018 PM2.5 Plan, the State’s 

precursor demonstration and 

conclusions are found in Chapter 7 

(‘‘Demonstration of Federal 

Requirements for 2012 PM2.5 Standard’’) 

and Appendix G (‘‘Precursor 

Demonstration’’). CARB also provides 

clarifying information on its precursor 

assessment, including an Attachment A 

to its letter transmitting the 2018 PM2.5

Plan to the EPA 77 and further 

clarifications in four email 

transmittals.78

The State estimates that 

anthropogenic emissions of NOX, 

ammonia, SOX, and VOC will decrease 

by 64%, 1%, 6%, and 9%, respectively, 

between 2013 and 2025.79 The 2018 

PM2.5 Plan provides both concentrationbased and sensitivity-based analyses of 

precursor contributions to ambient 

PM2.5 concentrations in the SJV. Based 

on these analyses, the State concludes 

that emissions of NOX (as well as direct 

PM2.5) contribute significantly to 

ambient PM2.5 levels that exceed the 

PM2.5 NAAQS in the SJV but ammonia, 

SOX, and VOC do not contribute 

significantly to such exceedances. 

While these analyses are primarily 

designed to evaluate the role of 

precursors in attaining the 2006 24-hour 

PM2.5 NAAQS by 2024 and the 2012 

annual PM2.5 NAAQS by 2025, they are 

important to the consideration of 

precursors for the State’s Moderate area 

plan because they are based on updated 

data (e.g., updated emissions 

inventories, as discussed in section IV.A 

of this proposed rule), use an updated 

methodology to evaluate the sensitivity 

of ambient PM2.5 to a range of precursor 

emission reductions, consistent with the 

EPA’s guidance, and best reflect the 

State’s understanding of the control 

strategies being implemented in the SJV. 

We summarize the State’s analyses 

and conclusions in the following 

paragraphs. For ammonia, SOX, and 

VOC, CARB assesses the 2015 annual 

average concentration of each precursor 

in ambient PM2.5 at Bakersfield, for 

which the necessary speciated PM2.5

data is available and where the highest 

PM2.5 design values have been recorded 

in most years, and compares those 

concentrations to the recommended 

annual average contribution threshold 

of 0.2 mg/m3 from the EPA’s ‘‘Draft PM2.5

Precursor Guidance’’ 80 available at the 

time the State developed the SIP.81 The 

2015 annual average contributions of 

ammonia, SOX, and VOC are 5.2 mg/m3, 

1.6 mg/m3 and 6.2 mg/m3, respectively. 

Given that these levels are well above 

the EPA’s recommended contribution 

threshold in the Draft PM2.5 Precursor 

Guidance, the State models the 

sensitivity of ambient PM2.5 in the SJV 

to reductions in each precursor 

pollutant. For direct PM2.5 and NOX, the 

State models the sensitivity of ambient 

PM2.5 in the SJV to a 30% reduction in 

anthropogenic emissions of each 

pollutant in 2013, 2020, and 2024.82 The 

State concludes that direct PM2.5 and 

NOX emissions reductions will continue 

to have a significant impact on annual 


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83 Id. Ch. 7, 7–7; and 2018 PM2.5 Plan, App. G, 

2. CARB presents its sensitivity analysis for 

emission reductions in direct PM2.5 and NOX in the 

plan’s attainment demonstration appendix. 2018 

PM2.5 Plan, App. K, Table 46 (annual average design 

values) and Table 50 (24-hour average design 

values). 

84 2018 PM2.5 Plan, Ch. 7, 7–7. The 2018 PM2.5

Plan precursor demonstration assumes that 2025 

attainment year sensitivities are very similar to 

those modeled in 2024. 2018 PM2.5 Plan, App. G, 

10. We note that the State only modeled 30% and 

70% reductions in SOX for 2013, finding that the 

sensitivity of ambient PM2.5 to such changes were 

below the EPA’s recommended threshold. 

85 Id. at App. G, tables 2 through 7 for ammonia, 

tables 8 and 9 for SOX, and tables 10 through 15 

for VOC. 

86For a more detailed summary of the State’s 

precursor demonstration in the 2018 PM2.5 Plan for 

the 2006 24-hour PM2.5 NAAQS, see the EPA’s 

‘‘Technical Support Document, EPA Evaluation of 

PM2.5 Precursor Demonstration, San Joaquin Valley 

PM2.5 Plan for the 2006 PM2.5 NAAQS,’’ February 

2020 (‘‘EPA’s 24-hour PM2.5 Precursor TSD’’). 

87 2018 PM2.5 Plan, App. G, 5. 

88PM2.5 Precursor Guidance, 18–19 

(consideration of additional information), 31 

(available emission controls), and 35–36 

(appropriateness of future year versus base year 

sensitivity). 

89 2018 Plan, App. G, 8. 

90For the 2016 PM2.5 Plan precursor 

demonstration, CARB modeled a 15% increase and 

15% decrease in a precursor and took the difference 

between the resulting PM2.5 concentrations to 

estimate the ambient PM2.5 response to a 30% 

change in the precursor, rather than a straight 30% 

reduction, which would be expected to slightly 

understate the response, as described in the EPA’s 

Ammonia Precursor TSD. Nevertheless, this is a 

reasonable approach and the State consulted with 

the EPA on whether this approach using thenavailable modeling runs would be acceptable. 

91For the 2018 PM2.5 Plan, the model 

performance is discussed further in section J (‘‘Air 

Quality Model Performance’’) of the EPA’s 

‘‘Technical Support Document, EPA Evaluation of 

Air Quality Modeling, San Joaquin Valley PM2.5

Plan for the 2006 PM2.5 NAAQS,’’ February 2020 

(‘‘EPA’s Modeling TSD’’). See further discussion in 

section IV.C of this proposed rule. 

and 24-hour PM2.5 design values in the 

SJV, with NOX reductions being 

particularly important.83

For ammonia, SOX, and VOC, the 

State then models the sensitivity of 

ambient PM2.5 to 30% and 70% 

reductions in anthropogenic emissions 

of each precursor pollutant in 2013 (the 

2018 PM2.5 Plan’s base year), 2020 (the 

modeled attainment year for the 1997 

PM2.5 NAAQS), and 2024 (the modeled 

attainment year for the 2006 PM2.5

NAAQS, and proxy for the modeled 

attainment year of 2025 for the 2012 

PM2.5 NAAQS).84 Depending on the 

analysis year and percentage precursor 

emission reduction, the sensitivity of 

ambient PM2.5 to reductions in annual 

average precursor emissions ranges from 

0.08 mg/m3 to 2.30 mg/m3 for ammonia; 

from ¥0.05 mg/m3 to 0.15 mg/m3 for 

SOX; and from ¥0.50 mg/m3 to 0.40 mg/ 

m3 for VOC.85

For ammonia, the modeled sensitivity 

of ambient PM2.5 levels to a 30% or 70% 

emission reduction exceed 0.2 mg/m3 in 

certain years at specific monitoring 

sites. We provide a detailed summary of 

these modeling results and our 

evaluations thereof in the ‘‘Technical 

Support Document, EPA Evaluation of 

Ammonia Precursor Demonstration, San 

Joaquin Valley Moderate Area PM2.5

Plan for the 2012 PM2.5 NAAQS,’’ 

August 2021 (‘‘EPA’s Ammonia 

Precursor TSD’’). In contrast, for SOX

and VOC, the modeled sensitivity of 

ambient PM2.5 levels to a 30% or 70% 

emission reduction in either precursor 

is below 0.2 mg/m3, including a 

disbenefit at certain monitoring sites 

(i.e., ambient PM2.5 level increase), in all 

scenarios except one. For 2013, the 

State’s modeling shows an ambient 

PM2.5 change greater than 0.2 mg/m3 in 

response to a 70% VOC emission 

reduction. According to the State, 

however, such sensitivity results do not 

reflect the atmospheric chemistry in the 

SJV given the projected emission 

reductions from 2013 to 2024 for all four 

PM2.5 precursors, especially for VOC 

and NOX.86

The State supplements the sensitivity 

analysis, particularly for ammonia, with 

consideration of additional information, 

including factors identified in the Draft 

PM2.5 Precursor Guidance, such as 

emission trends, the appropriateness of 

future year versus base year sensitivity, 

available emission controls, and the 

severity of nonattainment.87 The PM2.5

Precursor Guidance confirms that these 

factors may be relevant to a sensitivitybased contribution analysis.88

For ammonia, the State notes that a 

53% reduction in (baseline) NOX

emissions is projected to occur between 

2013 and 2024,89 so the conditions in 

the early years will not persist and the 

future year (2024) is more representative 

of the Valley’s ambient conditions than 

earlier years. The 2018 PM2.5 Plan’s 

precursor demonstration also presents a 

review of District agricultural rules that 

control VOC emissions and also provide 

ammonia co-benefits. The State 

concludes that a 30% reduction is a 

reasonable upper bound on the 

ammonia reductions to model. Finally, 

the 2018 PM2.5 Plan’s precursor 

demonstration presents extensive 

support for the State’s conclusion 

regarding an ambient excess of ammonia 

relative to NOX, i.e., that particulate 

ammonium nitrate formation is NOXlimited, beyond that presented in the 

2016 PM2.5 Plan’s precursor 

demonstration. 

3. EPA Evaluation and Proposed Action 

The EPA has evaluated the State’s 

precursor demonstrations in the 2016 

PM2.5 Plan, as supplemented and 

updated by the precursor 

demonstrations in the 2018 PM2.5 Plan, 

as well as other relevant information 

available to the EPA, consistent with the 

PM2.5 SIP Requirements Rule and the 

recommendations in the PM2.5 Precursor 

Guidance. Based on this evaluation, the 

EPA agrees with the State’s conclusion 

that NOX emissions contribute 

significantly to ambient PM2.5 levels that 

exceed the 2012 PM2.5 NAAQS in the 

SJV and that NOX emission sources, 

therefore, remain subject to control 

requirements under subparts 1 and 4 of 

part D, title I of the Act. Additionally, 

for the reasons provided in the 

following paragraphs, the EPA proposes 

to approve the State’s comprehensive 

precursor demonstrations for ammonia, 

SOX, and VOC based on a conclusion 

that emissions of these precursor 

pollutants do not contribute 

significantly to ambient PM2.5 levels that 

exceed the 2012 PM2.5 NAAQS in the 

SJV. 

The State based its analyses on the 

latest available data and studies 

concerning ambient PM2.5 formation in 

the SJV from precursor emissions. For 

the required concentration-based 

analysis, the State assessed the absolute 

annual average contribution of each 

precursor to ambient PM2.5 (i.e., in 

2015). Given the absolute 

concentrations in 2015 were above the 

EPA’s recommended contribution 

thresholds for both the 24-hour and 

annual average PM2.5 NAAQS, the State 

proceeded to a sensitivity-based 

analysis, consistent with the PM2.5 SIP 

Requirements Rule. 

For the sensitivity-based analysis, the 

State performed its analyses in a 

straightforward application of the EPA’s 

recommended approach—i.e., for each 

modeled year and level of emissions 

reduction (in percentages), the State 

estimated the ambient PM2.5 response 

using the procedure recommended in 

the PM2.5 Precursor Guidance, and 

compared the result to the EPA’s 

recommended contribution threshold.90

The EPA finds that the performance of 

the photochemical models were 

adequate for use in estimating the 

ambient PM2.5 responses.91 In 

particular, for the 2018 PM2.5 Plan 

precursor demonstration, the State 

considered the EPA’s recommended 

range of emission reductions (30% to 

70%) for the 2013 base year, 2020 (an 

interim year), and 2024 (as a proxy for 

the projected 2025 attainment year for 

the 2012 PM2.5 NAAQS), and quantified 


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92PM2.5 Precursor Guidance, 35. 

93See, e.g., Parrish, D., ‘‘Synthesis of Policy 

Relevant Findings from the CalNex 2010 Field 

Study, Final Report to the Research Division of the 

California Air Resources Board,’’ 2014, 63, https:// 

www.esrl.noaa.gov/csd/projects/calnex/; and Kelly, 

J.T. et al. 2018, ‘‘Modeling NH4NO3 over the San 

Joaquin Valley during the 2013 DISCOVER–AQ 

campaign,’’ Journal of Geophysical Research: 

Atmospheres, 123, 4727–4745, https://doi.org/ 

10.1029/2018JD028290 at 4731. See also the EPA’s 

Ammonia Precursor TSD for further discussion of 

ammonia research studies. 

94CARB’s April 26, 2021, Precursor Clarification. 

95NASA, ‘‘Deriving Information on Surface 

conditions from COlumn and VERtically Resolved 

Observations Relevant to Air Quality,’’ available at 

https://www.nasa.gov/mission_pages/discover-aq/ 

index.html. 

96 2018 PM2.5 Plan, 6–7, and App. G, G–9 to G– 

10; the CARB 2018 Staff Report, App. C, 12–15; and 

Submittal Letter, Attachment A. 97Lurmann et al. 2006, ‘‘Processes Influencing 

Secondary Aerosol Formation in the San Joaquin 

Valley during Winter,’’ Journal of the Air & Waste 

Management Association (1995) 56(12):1679–93, 

https://doi.org/10.1080/10473289.2006.10464573; 

Markovic et al., 2014, ‘‘Measurements and 

modeling of the inorganic chemical composition of 

fine particulate matter and associated precursor 

gases in California’s San Joaquin Valley during 

CalNex 2010,’’ Journal of Geophysical Research— 

Atmospheres, 119, 6853–6866, https://doi.org/ 

10.1002/2013JD021408. CalNex, or California 

Research at the Nexus of Air Quality and Climate 

Change, was a NOAA-sponsored field study during 

summer 2010. https://www.esrl.noaa.gov/csd/ 

projects/calnex/. 

98 40 CFR 51.1006 (a)(1)(i). 

the estimated response of ambient PM2.5

concentrations to precursor emission 

changes in the SJV. 

The State’s emissions projections in 

the 2016 PM2.5 Plan and the 2018 PM2.5

Plan show that baseline emissions of 

each of these precursors will decrease 

from the 2013 base year to 2021 and 

2025, respectively (i.e., none of these 

pollutants is projected to increase). 

These decreases are included in the 

State’s modeled projections of ambient 

PM2.5 levels in the SJV for purposes of 

demonstrating attainment and RFP. The 

State’s sensitivity analyses are 

consistent with these projections, in 

accordance with the EPA’s 

recommendations in the PM2.5 Precursor 

Guidance.92

In the subsections that follow, we 

summarize below our evaluation of the 

State’s precursor demonstrations for 

ammonia, SOX, and VOC for purposes of 

the 2012 PM2.5 NAAQS in the SJV. 

a. Ammonia Precursor Demonstration 

In the 2016 PM2.5 Plan, CARB 

estimates the ambient PM2.5 response to 

a 30% reduction in emissions in 2025 

and, in the 2018 PM2.5 Plan, CARB 

estimates the ambient PM2.5 response to 

both a 30% and a 70% emission 

reduction in 2013, 2020, and 2024. We 

have evaluated CARB’s sensitivity-based 

contribution analyses for 2013, 2020, 

and 2024 (in the 2018 PM2.5 Plan) and 

for 2025 (in the 2016 PM2.5 Plan), and 

CARB’s determination that 2024, as a 

proxy for the projected attainment year 

of 2025, is more representative of 

conditions in the SJV for purposes of a 

sensitivity-based analysis, as discussed 

in the following paragraphs. We find it 

appropriate for the State to consider 

additional information as part of its 

evaluation of whether the ammonia 

contribution is significant and to rely on 

the responses to the 30% modeled 

ammonia emissions reduction in its 

precursor demonstration for ammonia. 

We provide a detailed evaluation of the 

State’s precursor demonstration for 

ammonia emissions in the EPA’s 

Ammonia Precursor TSD. 

As part of its analysis in the 2016 

PM2.5 Plan, CARB estimates that the 

ambient PM2.5 response to a 30% 

reduction in ammonia emissions would 

range from 0.1 mg/m3 to 0.2 mg/m3 in 

2025 with 3 of 16 monitoring sites 

having a response of 0.2 mg/m3. 

However, the precursor demonstration 

in the 2018 PM2.5 Plan indicates that the 

ambient response to a 30% ammonia 

emission reduction would exceed the 

EPA’s recommended contribution 

threshold of 0.2 mg/m3 at a number of 

monitoring sites, primarily in the 2013 

and 2020 analysis years. For example, 

the sensitivity results for a 30% 

reduction in ammonia emission 

reductions in 2020 (the closest analysis 

year to 2021), show that the ambient 

PM2.5 response at 9 of 15 monitoring 

sites would exceed the 0.2 mg/m3

threshold. We consider two lines of 

reasoning provided by the State to 

support its conclusion that ammonia 

emissions do not contribute 

significantly to ambient PM2.5 levels that 

exceed the 2012 PM2.5 NAAQS in the 

SJV. 

First, multiple researchers have 

suggested that ammonia emissions are 

underestimated in the SJV by a factor of 

two to five or more.93 This conclusion 

is based on comparing ambient and 

satellite measurements to model results 

that incorporate estimates of ammonia 

emissions and comparing monitoring or 

modeling results to what would be 

expected based on the size(s) of the 

ammonia and other precursor (e.g., 

NOX) emission inventories. In a 

supplemental transmittal,94 CARB 

described the results of two analyses 

confirming the likely underestimation of 

ammonia emissions. CARB compared 

Community Multiscale Air Quality 

(CMAQ) model predictions of ammonia 

with the 2013 DISCOVER–AQ 95 aircraft 

measurements and found that ammonia 

was underpredicted, and noted that this 

would result in the response to 

ammonia reductions being 

overpredicted. CARB also compared 

2017 satellite measurements of 

ammonia with CMAQ model 

predictions and found that modeled 

ammonia concentrations were half of 

the magnitude of the satellite 

observations at some locations, and the 

modeled average in the SJV was about 

25% less than observed. As a result of 

the likely ammonia emissions 

underestimation, the modeled response 

to ammonia precursor reductions in the 

2018 PM2.5 Plan’s precursor 

demonstration may be unrealistically 

large. 

If ammonia emissions were increased 

in the modeling to correct the likely 

underestimation, then modeled 

ammonia would be more abundant 

relative to nitrate; particulate nitrate 

formation would be more NOX-limited, 

and less responsive to ammonia 

reductions; and the modeled response to 

ammonia reductions would be lower 

than is reported in the 2018 PM2.5 Plan’s 

precursor demonstration and likely 

below the EPA’s recommended 

contribution threshold at most monitors 

in 2021. 

In addition, an upward revision in the 

ammonia emission estimate would 

make the model response more 

consistent with the ambient 

measurement studies discussed in the 

submittal.96 The relevant studies 

suggest a very low ambient sensitivity to 

ammonia, based on measured excess 

ammonia relative to NOX, the 

abundance of particulate nitrate relative 

to gaseous NOX, and the large 

abundance of ammonia relative to nitric 

acid.97 The studies all conclude that 

there is a large amount of ammonia left 

over after reacting with NOX, so that 

ammonia emission reductions would be 

expected mainly to reduce the amount 

of ammonia excess, rather than to 

reduce the particulate amonium nitrate. 

Based on these evaluations, we find 

that a correction to the likely 

underestimation of the ammonia 

emission inventory would likely result 

in a modeled response to ammonia 

reductions below the 0.2 mg/m3

contribution threshold in 2021. 

Second, the air quality benefit of 

ammonia emission reductions is 

projected to decline steeply over time 

and both the Moderate and Serious area 

plans for the 2012 PM2.5 NAAQS for the 

SJV have been submitted to the EPA. 

While a concentration-based analysis is 

the initial step for a precursor 

demonstration under the PM2.5 SIP 

Requirements Rule,98 a precursor 


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99 40 CFR 51.1006 (a)(1)(ii). 

100An example of a disbenefit is ‘‘sulfate 

replacement,’’ which can occur at intermediate 

ammonia levels when there is not enough ammonia 

to fully react with the SOX and NOX present. 

Reducing SOX emissions reduces ambient 

particulate ammonium sulfate. For each ammonium 

sulfate, two ammonium ions are freed; both can 

combine with a nitrate, forming two particulate 

ammonium nitrate molecules. The net result of the 

SOX emissions decrease is then an increase in 

ambient PM2.5 concentration. See also the EPA’s 24- 

hour PM2.5 Precursor TSD, 17–18; and West, J.J., 

Ansari, A.S., Pandis, S.N., 1999, ‘‘Marginal PM2.5: 

Nonlinear aerosol mass response to sulfate 

reductions in the eastern United States,’’ Journal of 

the Air & Waste Management Association, 49, 

1415–1424. https://doi.org/10.1080/10473289.1999.

10463973. 

101 2018 PM2.5 Plan, App. G, tables 4 & 5, G–11. 

The result for the Madera site is unclear since its 

monitored concentrations are biased high. 102For 2025, the 2016 PM2.5 Plan states there are 

no sites are above the contribution threshold. The 

sensitivities show similar declines from 2020 to 

2025 of 58% for the monitoring site with the 

highest projected PM2.5 level and 46% averaged 

over all monitoring sites. Because only a single 

decimal place is provided for 2025, the percent 

declines are more approximate. Extrapolating the 

2018 PM2.5 Plan results to 2025, the percent 

declines are 55% and 40%, respectively, which are 

comparable to those for 2024. 103Parrish, D., ‘‘Synthesis of Policy Relevant 

Findings from the CalNex 2010 Field Study, Final 

Report to the Research Division of the California Air 

Resources Board,’’ 2014, 63, https://

www.esrl.noaa.gov/csd/projects/calnex/. 104 2018 PM2.5 Plan, App. B, tables B–2 (‘‘NOX’’) 

and B–5 (‘‘Ammonia’’), annual average tpd, Grand 

Total for San Joaquin Valley, B–7 and B–16. The 

ammonia to NOX ratio is 329.2/317.2 = 1.04 in 

2013; 325.9/203.3 = 1.6 in 2020; and 324.6/148.9 = 

2.2 in 2024. 

105 2018 PM2.5 Plan, App. G, tables 4 and 6. 

106Sensitivity for the year 2021 is being 

represented by model results for 2020. Given the 

declining NOX emissions and corresponding 

decline in ammonia sensitivity, the actual PM2.5

response to ammonia reductions for 2021 would be 

lower than stated. 

107 2018 PM2.5 Plan, App. G, tables 5 and 7, 11– 

12. The response to 2025 ammonia reductions 

would be lower than the values stated in the text, 

due to the effect of declining NOX emissions. 

demonstration may then proceed to a 

sensitivity-based contribution 

analysis 99 to consider how sensitive 

ambient PM2.5 levels would be to 

emissions reductions. Precursor 

concentration alone does not account 

for complications of meteorology and 

chemistry; ambient PM2.5 may be 

relatively insensitive to emissions 

reductions and, in some circumstances, 

emissions reductions may even result in 

increased ambient PM2.5, i.e., show a 

‘‘disbenefit.’’ 100

In selecting the analysis year for a 

precursor demonstration, we find it 

appropriate to consider changes in 

atmospheric chemistry that may occur 

between the base or current year and the 

attainment year because the changes 

may ultimately affect the nonattainment 

area’s progress toward expeditious 

attainment. Based on these 

considerations, we find it reasonable for 

the State to focus on the ambient PM2.5

response to ammonia emission 

reductions in 2024, rather than an 

earlier year, as the modeled response in 

2024 in the SJV better reflects the 

potential benefit of ammonia control 

measures for purposes of expeditious 

attainment of the 2012 PM2.5 NAAQS. 

We consider the precursor 

demonstration in the 2018 PM2.5 Plan as 

part of this evaluation, because the 2018 

PM2.5 Plan contains a Serious area 

attainment plan for the 2012 PM2.5

NAAQS based on modeled emissions 

projections for 2024 and 2025 that are 

relevant to our evaluation of the 

ammonia precursor demonstration in 

the 2016 PM2.5 Plan. The 2018 PM2.5

Plan provides updated analyses with 

comprehensive modeling and additional 

information beyond that provided in the 

2016 PM2.5 Plan, and the 2024 model 

results in the 2018 PM2.5 Plan 

corroborate the 2025 model results in 

the 2016 PM2.5 Plan. 

The State’s precursor demonstrations 

in the 2016 PM2.5 Plan and the 2018 

PM2.5 Plan show that ambient sensitivity 

to ammonia emission reductions in the 

SJV declines steeply over time. Between 

2020 and 2024, the modeled response to 

a 30% ammonia emission reduction 

declines by 50% at the BakersfieldPlanz monitoring site, which has the 

highest projected PM2.5 level, and by 

37% averaged over all monitoring sites. 

In absolute terms, the ambient PM2.5

response declines from 0.24 mg/m3 in 

2020 to 0.12 mg/m3 in 2024 at 

Bakersfield-Planz, and from 0.23 mg/m3

to 0.14 mg/m3 as averaged over all 

monitoring sites, with the decline being 

generally larger for the sites with the 

highest projected PM2.5 levels. Thus, 

between 2020 and 2024, the number of 

sites at which modeled sensitivity 

exceeds the 0.2 mg/m3 threshold 

declines from 9 of 15 to 1 or 2 of 

15.101 102 As discussed above, ammonia 

sensitivity declines because of the 

shifting atmospheric chemistry caused 

by NOX emissions decreases. NOX

emissions are projected to decrease 27% 

between 2020 and 2024 due to baseline 

measures (e.g., existing motor vehicle 

controls). The decreased NOX emissions 

will make ammonia more abundant 

relative to NOX, and even less of a 

limiting factor on PM2.5 formation. In 

other words, the model response in the 

future attainment year 2024 gives a 

more realistic assessment of the 

potential effect of ammonia controls 

than past or current conditions. 

Moreover, given the likely 

underestimate in ammonia emissions in 

the SJV, 2024 modeling results may be 

more representative even of current 

conditions than 2020 modeling results. 

For example, if 2013 ammonia 

emissions are underestimated by a 

factor of three, as suggested by the 

CalNex summary report,103 then the 

2013 ratio of ammonia to NOX

emissions of 1.04 should be about 3.1, 

instead. The emissions ratio of ammonia 

to NOX in 2024 is 2.2, which is closer 

to 3.1 than the emissions ratio of 

ammonia to NOX in 2020, which is 

1.6.104 Using 2024 modeling results 

partly compensates for the likely 

ammonia emissions underestimation. 

Finally, the decision on whether to 

control ammonia does not affect the 

attainment year for the 2012 annual 

PM2.5 NAAQS. From the 2020 

sensitivity results,105 a 30% reduction 

in ammonia emissions would reduce the 

projected PM2.5 level in 2021 106 by 0.24 

mg/m3. The design value would decrease 

from a 2020 baseline value of 14.6 mg/ 

m3 down to 14.3 mg/m3. The State uses 

a 30% ammonia emission reduction as 

an upper bound in the modeling but 

shows that even a 70% ammonia 

emission reduction would reduce the 

design value to only 13.8 mg/m3. The 

result of a 30% or even a 70% ammonia 

emission reduction, if those were 

possible, would still be well above the 

NAAQS level of 12.0 mg/m3. Attainment 

would remain impracticable in 2021. A 

decision to evaluate and possibly adopt 

additional ammonia controls in the 

2016 PM2.5 Plan would not remove the 

need for a Serious area plan identifying 

a later attainment year for the 2012 

PM2.5 NAAQS. 

Such reductions would also have 

little effect in 2025. Based on the 2024 

sensitivity results,107 if ammonia 

emissions were reduced by 30%, the 

area’s 12.0 mg/m3 design value would be 

reduced by 0.12 mg/m3, which would 

not be considered significant (it is below 

the EPA’s recommended threshold of 

0.2 mg/m3). A 70% reduction might 

lower the design value by 0.36 mg/m3 to 

11.7 mg/m3. Conceivably that could 

result in attainment of the 2012 PM2.5

NAAQS in 2024 rather than 2025, but it 

is not clear whether reductions of that 

magnitude are feasible. 

In sum, we find that the State 

quantified the sensitivity of ambient 

PM2.5 levels to reductions in ammonia 

emissions using appropriate modeling 

techniques that performed well; there is 

likely an underestimation of ammonia 

emissions in the SJV and, if corrected, 

the modeled response to ammonia 

reductions would be lower than 

reported; and the State’s choice of 2024 

and 2025 as the reference points for 

purposes of evaluating the sensitivity of 


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108 2018 PM2.5 Plan, App. G, 15–16, tables 8 and 

9. 

109 2018 PM2.5 Plan, App. G, 15. 

110CARB’s September 2019 Precursor 

Clarification. 

111 2018 PM2.5 Plan, App. G, 18–19, tables 10 and 

11. 

112 2018 PM2.5 Plan, App. G, 19–20. 

113EPA’s 2006 NAAQS Precursor TSD, 22. 

114Memorandum dated November 29, 2018, from 

Richard Wayland, Air Quality Assessment Division, 

Office of Air Quality Planning and Standards 

(OAQPS), EPA, to Regional Air Division Directors, 

EPA, Subject: ‘‘Modeling Guidance for 

Demonstrating Air Quality Goals for Ozone, PM2.5, 

and Regional Haze,’’ (‘‘Modeling Guidance’’), and 

Memorandum dated June 28, 2011 from Tyler Fox, 

Air Quality Modeling Group, OAQPS, EPA, to 

Regional Air Program Managers, EPA, Subject: 

‘‘Update to the 24 Hour PM2.5 NAAQS Modeled 

Attainment Test,’’ (‘‘Modeling Guidance Update’’). 

ambient PM2.5 levels to ammonia 

emission reductions is well-supported. 

Based on all of these considerations, the 

EPA proposes to approve the State’s 

demonstration that ammonia emissions 

do not contribute significantly to 

ambient PM2.5 levels that exceed the 

2012 PM2.5 NAAQS in the SJV. 

b. SOX Precursor Demonstration0.05 

As described in section IV.B.2 of this 

proposed rule, in the 2016 PM2.5 Plan, 

CARB estimated the ambient PM2.5

response to a 30% reduction in SOX

emissions in 2025 to range from 0.1 mg/ 

m3 to 0.2 mg/m3, with half the 

monitoring sites having a response of 

0.2 mg/m3. In the 2018 PM2.5 Plan, CARB 

estimated the 2013 ambient PM2.5

response to a 30% SOX emission 

reduction to range from ¥0.01 mg/m3 to 

0.07 mg/m3 and estimated the ambient 

PM2.5 response to a 70% SOX emission 

reduction to range from ¥0.05 mg/m3 to 

0.15 mg/m3.108 The State also provides 

an emissions trend chart that shows 

SOX emissions to be steady at 

approximately 8 tpd from 2013 through 

2024. Given that the relative levels of 

SOX and ammonia emissions over that 

timeframe remain similar, the State 

concludes that the 2013 sensitivities are 

also representative of future years.109

The State also provides the ambient 

PM2.5 responses in 2013, 2020, and 2024 

to 30% and 70% reductions in SOX

emissions, all of which are below the 

0.2 mg/m3 contribution threshold.110

We note that the 2016 PM2.5 Plan’s 

sensitivity estimates for 2025 are at or 

below the EPA’s recommended 

contribution threshold of 0.2 mg/m3, and 

that the 2018 PM2.5 Plan’s sensitivity 

estimates for 2013 are well below that 

threshold for both the 30% and 70% 

emission reduction scenarios and even 

negative for certain monitoring sites. 

Given that the latter precursor 

demonstration was based on updated 

data and an updated methodology, and 

the steady SOX emission levels over 

2013 to 2025 (as opposed to increases), 

the EPA agrees with the State’s 

conclusion that the 2013 modeled 

sensitivities provide a sufficient basis 

for the SOX precursor demonstration. 

The supplemental results provided by 

the State for 2020 and 2024 support this 

conclusion. 

Therefore, on the basis of these 

modeled ambient PM2.5 responses to 

SOX emission reductions in the SJV, and 

the facts and circumstances of the area, 

the EPA proposes to approve the State’s 

demonstration that SOX emissions do 

not contribute significantly to ambient 

PM2.5 levels that exceed the 2012 PM2.5

NAAQS in the SJV. 

c. VOC Precursor Demonstration 

In the 2016 PM2.5 Plan, CARB 

estimated the ambient PM2.5 response to 

a 30% difference in VOC emissions in 

2025 to range from ¥0.1 mg/m3 to 0.1 

mg/m3. In the 2018 PM2.5 Plan, the State 

found that the ambient PM2.5 response 

to VOC emission reductions were 

generally below the EPA’s 

recommended contribution threshold of 

0.2 mg/m3, and often predicted an 

increase in ambient PM2.5 levels in 

response to such reductions (i.e., a 

disbenefit), except for a 70% emission 

reduction for the 2013 base year, where 

the State predicted the ambient PM2.5

response to be above both recommended 

thresholds at a majority of sites.111

We note that the 2016 PM2.5 Plan’s 

sensitivity estimates for 2025 are at or 

below the EPA’s recommended 

contribution threshold of 0.2 mg/m3, and 

that the 2018 PM2.5 Plan’s sensitivity 

estimates for 2020 and 2024 are well 

below that threshold for both the 30% 

and 70% emission reduction scenarios, 

and even negative for certain monitoring 

sites. The State also provides an 

emissions trend chart that shows VOC 

emissions are projected to decrease by 

about 30 tpd, or 9% between 2013 and 

2020 as well as between 2013 and 2024, 

and concludes that 2013 sensitivity 

results are not representative into the 

future and that the 2020 and 2024 

results are representative.112 Finally, the 

State concludes that VOC emissions do 

not contribute significantly to PM2.5

levels that exceed the 2012 PM2.5

NAAQS. 

The EPA has evaluated and agrees 

with the State’s determination in the 

2018 PM2.5 Plan that the projected 2024 

attainment year is more representative 

of conditions in the SJV for sensitivitybased analyses and that VOC reductions 

in 2024 would mostly result in a 

disbenefit to ambient PM2.5 levels. The 

EPA agrees that the 9% VOC emissions 

decrease from 2013 to 2024 supports 

reliance on the 2024 modeling results. 

Furthermore, there is a large decrease in 

NOX emissions over this period, as 

described in section IV.B.2 of this 

proposed rule, that affects the 

atmospheric chemistry with respect to 

ambient PM2.5 formation from VOC 

emissions. The 9% VOC emission 

reductions and the vast majority of NOX

emissions reductions are expected to 

result from baseline measures already in 

effect. Therefore, we find it reasonable 

to rely on future year 2024 modeled 

responses to VOC reductions. The EPA 

also finds that the State provided a 

reasonable explanation for the VOC 

reduction disbenefit and evidence that it 

occurs in the SJV; as discussed in the 

EPA’s ‘‘Technical Support Document, 

EPA Evaluation of PM2.5 Precursor 

Demonstration, San Joaquin Valley 

PM2.5 Plan for the 2006 PM2.5 NAAQS,’’ 

February 2020 (‘‘EPA’s 2006 NAAQS 

Precursor TSD’’), VOC reductions led to 

less peroxyacetyl nitrate formation, and 

greater availability of nitrate to form 

particulate ammonium nitrate.113

For these reasons, we propose to 

approve the State’s demonstration that 

VOC emissions do not contribute 

significantly to ambient PM2.5 levels that 

exceed the 2012 PM2.5 NAAQS in the 

SJV. 

C. Air Quality Modeling 

1. Requirements for Air Quality 

Modeling 

Section 189(a)(1)(B) of the CAA 

requires each state in which a Moderate 

area is located to submit a plan that 

includes a demonstration (including air 

quality modeling) of either (i) 

attainment of the PM2.5 NAAQS by the 

applicable attainment date, or (ii) 

attainment by that date is impracticable. 

The 2016 PM2.5 Plan includes a 

demonstration that attainment by the 

Moderate attainment date is 

impracticable. 

The EPA’s PM2.5 modeling 

guidance 114 (‘‘Modeling Guidance’’ and 

‘‘Modeling Guidance Update’’) 

recommends that a photochemical 

model, such as the Comprehensive Air 

Quality Model with Extensions or 

CMAQ, be used to simulate a base case, 

with meteorological and emissions 

inputs reflecting a base case year, to 

replicate concentrations monitored in 

that year. The model application to the 

base year undergoes a performance 

evaluation to ensure that it satisfactorily 

corroborates the concentrations 

monitored in that year. The model may 

then be used to simulate emissions 

occurring in other years required for a 


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115 In this section, we use the terms ‘‘base case,’’ 

‘‘base year’’ or ‘‘baseline,’’ and ‘‘future year’’ as 

described in section 2.3 of the EPA’s Modeling 

Guidance. The ‘‘base case’’ modeling simulates 

measured concentrations for a given time period, 

using emissions and meteorology for that same year. 

The modeling ‘‘base year’’ (which can be the same 

as the base case year) is the emissions starting point 

for the plan and for projections to the future year, 

both of which are modeled for the attainment 

demonstration. Modeling Guidance, 37–38. Note 

that CARB sometimes uses ‘‘base year’’ 

synonymously with ‘‘base case’’ and ‘‘reference 

year’’ instead of ‘‘base year.’’ 

116Modeling Guidance, section 4.4, ‘‘What is the 

Modeled Attainment Tests for the Annual Average 

PM2.5 NAAQS.’’ 

117 81 FR 58010, 58048. 

118CAA section 189(b)(1). 

119 81 FR 58010, 58049. 

plan, namely the base year (which may 

differ from the base case year) and 

future year.115 The modeled response to 

the emission changes between those 

years is used to calculate relative 

response factors (RRFs) that are applied 

to the design value in the base year to 

estimate the projected design value in 

the future year for comparison against 

the NAAQS. Separate RRFs are 

estimated for each chemical species 

component of PM2.5, and for each 

quarter of the year, to reflect their 

differing responses to seasonal 

meteorological conditions and 

emissions. Because each species is 

handled separately, before applying an 

RRF, the base year design value must be 

speciated using available chemical 

species measurements—that is, each 

day’s measured PM2.5 concentration 

must be split into its species 

components. The Modeling Guidance 

provides additional detail on the 

recommended approach.116

The EPA has not issued modeling 

guidance specific to impracticability 

demonstrations but believes that a state 

seeking to make such a demonstration 

generally should provide air quality 

modeling similar to that required for an 

attainment demonstration.117 The main 

difference is that for an impracticability 

demonstration, the implementation of 

the SIP control strategy (including 

RACM) does not result in attainment of 

the standard by the Moderate area 

attainment date. 

For an attainment demonstration, a 

thorough review of all modeling inputs 

and assumptions (including consistency 

with EPA guidance) is especially 

important because the modeling must 

ultimately support a conclusion that the 

plan (including its control strategy) will 

provide for timely attainment of the 

applicable NAAQS. In contrast, for an 

impracticability demonstration, the end 

point is a reclassification to Serious, 

which triggers the requirement for a 

new Serious area attainment plan with 

a new air quality modeling analysis, and 

a new control strategy.118 Thus, the 

Serious area planning process would 

provide an opportunity to refine the 

modeling analysis and/or correct any 

technical shortcomings in the 

impracticability demonstration. 

Therefore, the burden of proof will 

generally be lower for an 

impracticability demonstration 

compared to an attainment 

demonstration.119

2. Summary of State’s Air Quality 

Modeling 

In the 2016 PM2.5 Plan, the State 

discussed its air quality modeling in 

section 2.3 (‘‘Summary of Modeling 

Results’’) and Appendix A (‘‘Air Quality 

Modeling’’) and concludes that it is not 

practicable to attain the 2012 PM2.5

NAAQS in the SJV by December 31, 

2021. The State used CMAQ (version 

5.02) to model three simulations: A 

2013 base year to demonstrate that the 

model reasonably reproduced observed 

PM2.5 concentrations, a 2013 reference 

base year simulation that excluded 

exceptional events such as wildfires, 

and a 2021 future year based on the 

reference year but using projected 2021 

emissions. For the base year simulation, 

CARB conducted photochemical 

modeling with the CMAQ model using 

inputs developed from routinely 

available meteorological and air quality 

data, as well as more detailed and 

extensive data from the DISCOVER–AQ 

field study conducted in January to 

February 2013. 

The State then generated site- and 

species-specific RRFs for the 

ammonium ion, nitrate ion, sulfate ion, 

organic carbon, elemental carbon, and a 

combined grouping of other primary 

PM2.5 material for the 2021 future year 

simulation and calculated future year 

design values by multiplying the 

species- and site-specific RRFs by the 

corresponding quarterly mean 

component concentrations. The State 

summed the quarterly mean 

components to determine quarterly 

mean PM2.5 concentrations, which it 

subsequently averaged to determine the 

annual design values. The future year 

design values reflect the weighted 

quarterly average concentration from the 

projections of five years of data. The 

State projected future year annual PM2.5

design values for the 2021 Moderate 

area attainment year for the 2012 PM2.5

NAAQS. 

The 2021 baseline simulation used 

emission levels projected from the 2013 

base year that reflect all control 

measures adopted by the time of the 

2016 PM2.5 Plan’s development that 

would be implemented by December 31, 

2021. This simulation indicates that the 

2012 annual PM2.5 standard will not be 

met in the SJV in 2021. The projected 

2021 control scenario design value is 

14.8 mg/m3 at Bakersfield-Planz, which 

is typically the monitoring site that 

records the highest PM2.5 levels in the 

SJV. 

The 2018 PM2.5 Plan includes a 

modeled demonstration projecting that 

the SJV will attain the 2012 annual 

PM2.5 NAAQS by December 31, 2025. It 

also includes a modeled demonstration 

projecting attainment of the 1997 annual 

PM2.5 NAAQS by December 31, 2020, 

with a design value of 14.6 mg/m3 at 

Bakersfield-Planz. While the plan does 

not explicitly have a demonstration of 

impracticability of attaining the 2012 

PM2.5 NAAQS by 2021, the latter 

projections of annual PM2.5

concentrations in 2020 provides 

additional information on which to 

judge the practicability of attaining by 

2021 in that it is the closest analysis 

year available and represents modeling 

based on updated data. These 

projections lend support for the 2016 

PM2.5 Plan indication that the 2012 

annual PM2.5 standard will not be met 

in the SJV in 2021. 

The Plan’s primary discussion of the 

photochemical modeling appears in 

Appendix K (‘‘Modeling Attainment 

Demonstration’’) of the 2018 PM2.5 Plan. 

The State briefly summarizes the area’s 

air quality problem in Chapter 2.2 (‘‘Air 

Quality Challenges and Trends’’) and 

summarizes the modeling results in 

Chapter 6.4 (‘‘Attainment 

Demonstration and Modeling’’) of the 

2018 PM2.5 Plan. The State provides a 

conceptual model of PM2.5 formation in 

the SJV as part of the modeling protocol 

in Appendix L (‘‘Modeling Protocol’’). 

Appendix J (‘‘Modeling Emission 

Inventory’’) describes emission input 

preparation procedures. The State 

presents additional relevant information 

in Appendix C (‘‘Weight of Evidence 

Analysis’’) of the CARB 2018 Staff 

Report, which includes ambient trends 

and other data in support of the 

demonstration of attainment by 2025. 

3. EPA Evaluation and Conclusion 

CARB’s air quality modeling approach 

investigated the many interconnected 

facets of modeling ambient PM2.5 in the 

SJV, including model input preparation, 

model performance evaluation, use of 

the model output for the numerical 

NAAQS attainment test, and modeling 

documentation. Specifically, this 

required the development and 

evaluation of a conceptual model, 

modeling protocol, episode (i.e., base 


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120The model performance is discussed further in 

section J (‘‘Air Quality Model Performance’’) of the 

EPA’s 2006 NAAQS Modeling TSD. 121 2018 PM2.5 Plan, App. K, 18. 

122 2016 PM2.5 Plan, App. A 48ff, tables 15 

through 18; 2018 PM2.5 Plan, App. K, 48ff, tables 

20 through 23. 

123 2016 PM2.5 Plan, App. A, 107ff, Supplemental 

materials, Figures S.37–S.52; 2018 PM2.5 Plan, App. 

K, 131ff, Supplemental materials, Figures S.41– 

S.52. 

124 2016 PM2.5 Plan, App. A, 46, Figure 13; 2018 

PM2.5 Plan, App. K, 54, Figure 14. 

125For a more detailed summary of the State’s air 

quality modeling in the 2018 PM2.5 Plan with 

respect to the 2006 24-hour PM2.5 NAAQS, rather 

than the 2012 annual PM2.5 NAAQS, please refer to 

the EPA’s 2006 NAAQS Modeling TSD. 

year) selection, modeling domain, 

CMAQ model selection, initial and 

boundary condition procedures, 

meteorological model choice and 

performance, modeling emissions 

inventory preparation procedures, 

model performance, attainment test 

procedure, and adjustments to baseline 

air quality for modeling. These analyses 

are generally consistent with the EPA’s 

recommendations in the Modeling 

Guidance. 

The model performance evaluation in 

section 5.2 (‘‘CMAQ Model Evaluation’’) 

of both Appendix A of the 2016 PM2.5

Plan and Appendix K of the 2018 PM2.5

Plan included statistical and graphical 

measures of model performance. 

The EPA previously evaluated and 

approved the modeling conducted for 

the 2006 24-hour PM2.5 NAAQS as part 

of the 2018 PM2.5 Plan; see the EPA’s 

‘‘Technical Support Document, EPA 

Evaluation of Air Quality Modeling, San 

Joaquin Valley PM2.5 Plan for the 2006 

PM2.5 NAAQS,’’ February 2020 (‘‘EPA’s 

2006 NAAQS Modeling TSD’’) 

accompanying that action for details.120

The conclusions in the EPA’s 2006 

NAAQS Modeling TSD focused on the 

24-hour PM2.5 NAAQS; in this notice we 

extend the evaluation with information 

specific to the annual PM2.5 NAAQS. 

Unless otherwise noted, the discussion 

applies to both the modeling in both the 

2016 PM2.5 Plan (Appendix A) and 2018 

PM2.5 Plan (Appendix K), since they 

followed the same model platform 

development procedures, and had 

identical meteorological inputs, very 

similar emissions inputs, and very 

similar model performance. 

Most aspects of the 2018 PM2.5 Plan 

modeling and the EPA’s evaluation of it 

are the same for the 24-hour and the 

annual averaging times, and the EPA 

has found them adequate. These include 

the modeling protocol, choice of model, 

meteorological modeling, modeling 

emissions inventory, choice of model, 

modeling domain, and procedures for 

model performance evaluation. One 

aspect that differs between the 24-hour 

and annual averaging times is the 

specific calculation procedure for 

estimating a future design value. In the 

Modeling Guidance, for both averaging 

times, the model is used to calculate 

RRFs, the ratio of modeled future 

concentrations to base year 

concentrations, and the RRF is applied 

to monitored base year concentrations. 

This is done for each monitor, PM2.5

species, and calendar quarter. But for 

the 24-hour averaging time, the 

procedure uses the highest individual 

concentration days in each quarter, 

whereas for the annual average, it uses 

the average of all days in each quarter. 

The EPA previously found that the 

procedures used in the 2018 PM2.5 Plan 

for the 24-hour PM2.5 NAAQS generally 

followed the EPA’s recommendations 

and were adequate. For the current 

action, the EPA finds that State 

procedures 121 for estimating future 

design values for the annual PM2.5

NAAQS generally followed the EPA’s 

recommendations and are adequate. 

Another modeling aspect that can 

differ between 24-hour and annual 

average is the focus of the model 

performance evaluation on the 

respective averaging times. For the 24- 

hour average, it is especially important 

that modeled concentrations on the 

highest days are comparable to those on 

the highest monitored days, since 

calculation of the design value for the 

24-hour PM2.5 NAAQS uses the 98th 

percentile concentrations, i.e., the top 

2%. For the annual average, peak 

concentrations continue to be 

important, but lower concentration days 

are also important since all days are 

included in the average. Under- and 

over-predictions on non-peak days may 

average out and have little overall effect 

on the modeled annual concentration, 

but systematic underprediction on nonpeak days could lead to model 

underprediction of the annual average 

concentration. This problem of model 

bias is mitigated by the use of the model 

in a relative sense as recommended in 

the Modeling Guidance. In the RRF, 

model bias ‘‘cancels out’’ to a degree 

since it would be present in both its 

numerator (future year) and its 

denominator (base year); and applying 

the RRF to monitored base year 

concentration anchors the final model 

prediction to unbiased real-world 

concentrations. Further, RRFs are 

calculated on a quarterly basis, so the 

bias correction can better account for 

emissions sources and atmospheric 

chemistry that differ between the 

seasons. 

The 2018 PM2.5 Plan did not have a 

separate model performance evaluation 

for the 24-hour and annual PM2.5

averaging times; it used statistical and 

graphical analyses applicable to both. 

For the most part, the EPA’s 2006 

NAAQS Modeling TSD did not 

distinguish between the two averaging 

times either but drew conclusions for 

the 24-hour averaging time rather than 

the annual averaging time. It did note a 

large negative bias (underprediction) in 

the ammonium and nitrate performance 

statistics 122 for the 2nd quarters for 

monitoring sites in Bakersfield, Fresno, 

and Visalia; and we add here that the 

3rd quarter has similar negative bias. 

The negative model bias in the 2016 

PM2.5 Plan was slightly better than in 

the 2018 PM2.5 Plan, i.e., the 

underprediction was slightly less. 

Underprediction of total PM2.5 in the 

2nd and 3rd quarters is also evident in 

time series plots for most monitoring 

sites, though by only a small amount for 

several monitoring sites.123 The EPA’s 

2006 NAAQS Modeling TSD noted that 

since those quarters have concentrations 

that are less than half of those in the 1st 

and 4th, this may not be much of a 

concern for the annual average. (It is of 

less concern for the 24-hour average, 

since peak 24-hour concentrations occur 

in winter, i.e., in the 1st and 4th 

quarters.) As noted above, the RRF 

procedure removes much of this bias, so 

the underprediction in the model 

performance evaluation does not 

directly translate into an underpredicted 

2020 design value. In addition, the 2018 

PM2.5 Plan shows that annual model 

performance for each PM2.5 species is 

quite good relative to that seen in other 

modeling studies, for multiple 

performance statistics.124

The high days are generally captured 

by the model, even though some are 

underpredicted in December at certain 

monitoring sites such as Fresno. 

Overall, the modeled site maxima are 

comparable to the measurements; also, 

the frequency of high and low days 

generally matches observations so the 

annual as well as the daily model 

performance is acceptable. 

The EPA evaluated the State’s choice 

of model for the impracticability 

demonstration and the extensive 

discussion in the 2016 PM2.5 Plan about 

modeling procedures, tests, and 

performance analyses, as well as the 

State’s modeling choices, procedures, 

test, and performance analyses in the 

2018 PM2.5 Plan.125 We find the State’s 

analyses consistent with the EPA’s 

guidance on modeling for PM2.5

attainment planning purposes. Based on 

these reviews, we find that the modeling 

in the 2016 PM2.5 Plan and 2018 PM2.5


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126This interpretation is consistent with guidance 

provided in the General Preamble, 13540. 

127 81 FR 58010, 58035. 

128 General Preamble, 13541 and 57 FR 18070, 

18073–18074. 

129 40 CFR 51.1000, 51.1009(a)(4)(i)(B), and 

51.1009(a)(4)(ii)(B). 

130 40 CFR 51.1009(a)(3). 

131 40 CFR 51.1009(a)(3); see also 57 FR 18070, 

18073–18074. 

132 Id. 

133 57 FR 18070, 18074. 

134 2016 PM2.5 Plan, Attachment 1 (comprising 

2015 PM2.5 Plan, App. C (‘‘BACM and MSM for 

Stationary and Area Sources’’)) and 2016 Ozone 

Plan, App. C (‘‘Stationary and Area Source Control 

Strategy Evaluations’’). See also SJVUAPCD 

Governing Board Resolution 15–4–7A, April 16, 

2015 (adopting the 2015 PM2.5 Plan) and 

SJVUAPCD Governing Board Resolution 16–6–20, 

June 16, 2016 (adopting the 2016 Ozone Plan). 

135 2016 PM2.5 Plan, Attachment 2 (comprising 

2015 PM2.5 Plan, App. D (‘‘BACM and MSM for 

Mobile Sources (Provided by ARB)’’) and 2016 

Ozone Plan, App. D (‘‘Mobile Source Control 

Strategy’’). See also CARB Resolution 15–9, May 21, 

2015 (adopting the 2015 PM2.5 Plan) and CARB 

Resolution 16–8, July 21, 2016 (adopting the 2016 

Ozone Plan). 

136 2016 PM2.5 Plan, Ch. 3, 3–5 to 3–6. 

137 Id. 

Plan is adequate for the purposes of 

supporting the RFP demonstration and 

the demonstration of impracticability in 

the 2016 PM2.5 Plan. 

D. Reasonably Available Control 

Measures and Control Strategy 

1. Requirements for RACM/RACT and 

Control Strategies 

The general subpart 1 attainment plan 

requirement for RACM/RACT is 

described in CAA section 172(c)(1), 

which requires that attainment plan 

submissions ‘‘provide for the 

implementation of all reasonably 

available control measures as 

expeditiously as practicable (including 

such reductions in emissions from 

existing sources in the area as may be 

obtained through the adoption, at a 

minimum, of reasonably available 

control technology)’’ and provide for 

attainment of the NAAQS. 

The attainment planning 

requirements specific to PM2.5 under 

subpart 4 likewise impose an obligation 

upon states with nonattainment areas 

classified as Moderate to develop 

attainment plans that require RACM/ 

RACT on sources of direct PM2.5 and all 

PM2.5 plan precursors. CAA section 

189(a)(1)(C) requires that Moderate area 

PM2.5 SIPs contain provisions to assure 

that RACM/RACT are implemented no 

later than four years after designation of 

the area. The EPA reads CAA section 

172(c)(1) and 189(a)(1)(C) together to 

require that attainment plans for 

Moderate nonattainment areas provide 

for the implementation of RACM/RACT 

for existing sources of PM2.5 and those 

PM2.5 precursors subject to control in 

the nonattainment area as expeditiously 

as practicable but no later than four 

years after designation.126

The PM2.5 SIP Requirements Rule 

defines RACM as ‘‘any technologically 

and economically feasible measure that 

can be implemented in whole or in part 

within 4 years after the effective date of 

designation of a PM2.5 nonattainment 

area and that achieves permanent and 

enforceable reductions in direct PM2.5

emissions and/or PM2.5 plan precursor 

emissions from sources in the area. 

RACM includes reasonably available 

control technology (RACT).’’ 127 The 

EPA has historically defined RACT as 

the lowest emission limitation that a 

particular stationary source is capable of 

meeting by the application of control 

technology that is reasonably available 

considering technological and economic 

feasibility.128

Under the PM2.5 SIP Requirements 

Rule, those control measures that 

otherwise meet the definition of RACM 

but ‘‘can only be implemented in whole 

or in part during the period beginning 

4 years after the effective date of 

designation of a nonattainment area and 

no later than the end of the sixth 

calendar year following the effective 

date of designation of the area’’ must be 

adopted and implemented as 

‘‘additional reasonable measures.’’ 129

States must provide written 

justification in a SIP submission for 

eliminating potential control options 

from further review on the basis of 

technological or economic 

infeasibility.130 An evaluation of 

technological feasibility may include 

consideration of factors such as a 

source’s process and operating 

conditions, raw materials, physical 

plant layout, and non-air quality and 

energy impacts (e.g., increased water 

pollution, waste disposal, and energy 

requirements).131 An evaluation of 

economic feasibility may include 

consideration of factors such as cost per 

ton of pollution reduced (costeffectiveness), capital costs, and 

operating and maintenance costs.132

Absent other indications, the EPA 

presumes that it is reasonable for similar 

sources to bear similar costs of emission 

reductions. Economic feasibility of 

RACM/RACT is thus largely informed 

by evidence that other sources in a 

source category have in fact applied the 

control technology, process change, or 

measure in question in similar 

circumstances.133

Consistent with these requirements, 

CARB and SJVUAPCD must implement 

RACM, including RACT, for sources of 

direct PM2.5 and PM2.5 plan precursors 

no later than April 15, 2019, and must 

implement additional reasonable 

measures for these sources no later than 

December 31, 2021. 

2. Summary of State’s Control Strategy 

The RACM/RACT evaluation for 

sources of direct PM2.5 and NOX

emissions in the SJV area is presented 

in Chapter 3 of the 2016 PM2.5 Plan and 

in Attachment 1 and Attachment 2 to 

the 2016 PM2.5 Plan. Attachment 1 to 

the 2016 PM2.5 Plan contains (1) a copy 

of the BACM/BACT and MSM control 

strategy evaluation for stationary and 

area sources that the District adopted on 

April 16, 2015, as part of its ‘‘2015 Plan 

for the 1997 PM2.5 Standard’’ (‘‘2015 

PM2.5 Plan’’), and (2) a copy of the 

RACM/RACT control strategy 

evaluation for stationary and area 

sources that the District adopted on June 

16, 2016, as part of its ‘‘2016 Plan for 

the 2008 8-Hour Ozone Standard’’ 

(‘‘2016 Ozone Plan’’).134 Attachment 2 

to the 2016 PM2.5 Plan contains (1) a 

copy of the BACM/BACT and MSM 

control strategy evaluation for mobile 

sources that CARB adopted on May 21, 

2015, as part of the 2015 PM2.5 Plan, and 

(2) a copy of the RACM/RACT control 

strategy evaluation for mobile sources 

that CARB adopted on July 21, 2016, as 

part of the 2016 Ozone Plan.135

The 2015 PM2.5 Plan and 2016 Ozone 

Plan contain comprehensive analyses to 

identify potential emission reduction 

opportunities for sources of direct PM2.5

and NOX emissions and to determine 

whether additional measures would be 

technologically and economically 

feasible for implementation in the 

SJV.136 The District states in the 2016 

PM2.5 Plan that it has not identified any 

new emission control technologies that 

could further reduce emissions in the 

SJV area, that the cost of technologies 

recently found not to be cost-effective 

has not changed, and that potential 

additional measures remain 

economically infeasible, consistent with 

the analyses and conclusions in the 

2015 PM2.5 Plan and the 2016 Ozone 

Plan.137 Based on these analyses, the 

District concludes that the 2016 PM2.5

Plan satisfies the RACM/RACT 

requirement for stationary and area 

sources of direct PM2.5 and NOX

emissions. The 2018 PM2.5 Plan, 

submitted May 10, 2019, supplements 

these analyses by providing updated 

evaluations of potential control 

measures for sources of direct PM2.5 and 

NOX emissions and the District’s 

rationale for finding that additional 


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138 2018 PM2.5 Plan, App. C (‘‘Stationary Source 

Control Measure Analyses’’). 

139 2016 PM2.5 Plan, 3–6. 

140CARB 2016 Staff Report, 13. 

141 2018 PM2.5 Plan, App. D (‘‘Mobile Source 

Control Measure Analyses’’). 

142 2016 PM2.5 Plan, 3–6. 

143 2016 PM2.5 Plan, 3–23 to 3–24. See also 2016 

PM2.5 Plan, Attachment 2, App. D, section D.2.2 (D– 

16 through D–18) and Attachment D (‘‘Adopted 

Transportation Control Measures’’). 

144 2016 PM2.5 Plan, 3–6. 

145 2018 PM2.5 Plan, App. D, D–127 to D–128 

(noting that the MPOs revisited the minimum cost 

effectiveness standard during the development of 

their 2018 Regional Transportation Plans and 2019 

Federal Transportation Improvement Program and 

concluded that they were implementing all 

reasonable transportation control measures). 

146 84 FR 3302. 

147 85 FR 44192 (final rule approving 2018 PM2.5

Plan as meeting, inter alia, BACM/BACT and MSM 

requirements for 2006 PM2.5 NAAQS). Because the 

RACM/RACT and additional reasonable measure 

control strategy in the 2016 PM2.5 Plan is very 

similar to the BACM/BACT and MSM control 

strategy in the 2018 PM2.5 Plan, and because the 

State’s and District’s control measure evaluations in 

the 2016 PM2.5 Plan substantially overlap with their 

BACM/BACT and MSM control evaluations in the 

2018 PM2.5 Plan, we rely primarily on our 

evaluation of the State’s and District’s BACM/BACT 

and MSM control measure evaluations in the 2018 

PM2.5 Plan (see proposed rule, 85 FR 17382 (March 

27, 2020) and final rule, 85 FR 44192) to support 

our evaluation of the RACM/RACT and additional 

reasonable measure control strategy in the 2016 

PM2.5 Plan. 

148EPA, Region IX, Air Division, ‘‘Technical 

Support Document, EPA Evaluation of RACM/ 

RACT and Additional Reasonable Measures, San 

Joaquin Valley Moderate Area Plan for the 2012 

PM2.5 NAAQS,’’ August 2021. 

149The 2018 PM2.5 Plan identifies Rule 4901 

(‘‘Wood Burning Fireplaces and Wood Burning 

Heaters’’), as amended June 20, 2019, as an 

additional reasonable measure that is scheduled for 

implementation beginning in 2020. 2018 PM2.5

Plan, Table 4–4 (‘‘Proposed Regulatory Measures’’). 

The EPA approved Rule 4901 into the California 

SIP on July 22, 2020. 85 FR 44206 (final rule 

approving Rule 4901) and 85 FR 44192 

(determination that Rule 4901 implements BACM 

and MSM for residential wood burning). 

150 General Preamble, 13539 and 13541–13542. 

151 81 FR 58010, 58115. 

control measures are not technologically 

and economically feasible for 

implementation in the SJV.138

With respect to mobile sources, the 

2016 PM2.5 Plan states that CARB has 

implemented the most stringent mobile 

source emissions control program in the 

nation, including emission standards for 

new vehicles, in-use programs for 

exiting vehicles and fleets, cleaner fuels, 

and incentive programs to accelerate 

penetration of cleanest vehicles.139

CARB states that its analyses of these 

mobile source control measures are 

presented in the 2015 PM2.5 Plan and 

the 2016 Ozone Plan (included as 

Attachment 2 to the 2016 PM2.5 Plan) 

and states that there are no additional 

reasonably available control measures 

that would advance attainment of the 

PM2.5 NAAQS in the SJV.140 Based on 

these analyses, CARB concludes that the 

2016 PM2.5 Plan satisfies the RACM/ 

RACT requirement for mobile sources of 

direct PM2.5 and NOX emissions. The 

2018 PM2.5 Plan, submitted May 10, 

2019, supplements these analyses by 

providing updated evaluations of 

CARB’s mobile source control measures 

and its rationale for finding that 

additional control measures are not 

technologically and economically 

feasible for implementation in the SJV at 

this time.141

Finally, with respect to transportation 

control measures (TCMs), the 2016 

PM2.5 Plan states that the eight county 

metropolitan planning organizations 

(MPOs) of the SJV (‘‘SJV MPOs’’) 

identified and evaluated all TCMs 

during development of the plan.142 The 

plan states that the SJV MPOs 

implement TCMs in CAA section 108(f) 

consistent with the Congestion 

Mitigation and Air Quality cost 

effectiveness policy when developing 

each MPO’s Regional Transportation 

Plan. In 2016 the Valley MPOs revisited 

the minimum cost effectiveness 

standard for TCMs during the 

development of the MPOs’ 2017 Federal 

Transportation Improvement 

Program.143 The District concludes that 

the Valley MPOs are implementing all 

reasonable TCMs under the MPOs’ 

jurisdictions and that adoption of 

additional TCMs would not expedite 

attainment of the 2012 PM2.5 NAAQS in 

the SJV.144 The 2018 PM2.5 Plan, 

submitted May 10, 2019, supplements 

these analyses by providing an updated 

discussion of the transportation control 

measures being implemented in the 

SJV.145

3. EPA’s Evaluation and Proposed 

Action 

We have reviewed the State and 

District’s demonstrations in the 2016 

PM2.5 Plan concerning RACM/RACT 

and additional reasonable measures for 

mobile, stationary, and area sources of 

direct PM2.5 and one PM2.5 plan 

precursor (i.e., NOX) in the SJV. Our 

evaluation relies primarily on our 

previous evaluations of the State and 

District rules in connection with our 

February 12, 2019 approval of the SJV 

RACM demonstration for the 2008 

ozone NAAQS (for NOX emission 

sources) 146 and in connection with our 

July 22, 2020 approval of the State and 

District’s demonstrations to meet the 

BACM (including BACT) and MSM 

requirements for the 2006 PM2.5

NAAQS.147 We provide a detailed 

discussion of these evaluations in the 

technical support document for this 

proposed rule.148 Based on these 

reviews, we propose to find that the 

District’s rules provide for the 

implementation of RACM and 

additional reasonable measures 149 for 

stationary and area sources of direct 

PM2.5 and NOX and that CARB’s current 

program implements RACM and 

additional reasonable measures for 

mobile sources of direct PM2.5 and NOX

emissions for purposes of the 2012 

PM2.5 NAAQS in the SJV. 

With respect to transportation 

controls, we find that the SJV MPOs 

have well-established TCM 

development programs in which TCMs 

are continuously identified, reviewed, 

and evaluated throughout the 

transportation planning process. 

Overall, we believe that the programs 

developed and administered by CARB 

and the SJV MPOs provide for the 

implementation of RACM and 

additional reasonable measures for 

sources of direct PM2.5 and NOX in the 

SJV. 

For these reasons, we propose to find 

that the 2016 PM2.5 Plan provides for the 

implementation of RACM and 

additional reasonable measures for all 

sources of direct PM2.5 and NOX as 

expeditiously as practicable, for 

purposes of implementing the 2012 

PM2.5 NAAQS in the SJV in accordance 

with the requirements of CAA section 

189(a)(1)(C) and 40 CFR 51.1009. 

E. Nonattainment New Source Review 

Requirements Under CAA Section 

189(e) 

Section 189(e) of the CAA specifically 

requires that the control requirements 

applicable to major stationary sources of 

direct PM2.5 also apply to major 

stationary sources of PM2.5 precursors, 

except where the Administrator 

determines that such sources do not 

contribute significantly to PM2.5 levels 

that exceed the standards in the area.150

The control requirements applicable to 

major stationary sources of direct PM2.5

in a Moderate PM2.5 nonattainment area 

include, at a minimum, the 

requirements of an NNSR permit 

program meeting the requirements of 

CAA sections 172(c)(5) and 189(a)(1)(A). 

In the PM2.5 SIP Requirements Rule, we 

established a deadline for states to 

submit NNSR plan revisions to 

implement the PM2.5 NAAQS 18 months 

after an area is initially designated and 

classified as a Moderate nonattainment 

area.151

California submitted NNSR SIP 

revisions for the SJV to address the 

subpart 4 requirements for Moderate 

PM2.5 nonattainment areas on May 19, 


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152Letter dated May 19, 2011, from Robert D. 

Fletcher, Deputy Executive Officer, CARB, to Jared 

Blumenfeld, Regional Administrator, EPA Region 

IX. 

153 79 FR 55637. 

154 81 FR 58010, 58048 and 58049. 

2011.152 The EPA fully approved these 

SIP revisions on September 17, 2014.153

California also submitted NNSR SIP 

revisions for the SJV to address the 

subpart 4 requirements for Moderate 

and Serious PM2.5 nonattainment areas 

on November 20, 2019. The EPA is 

evaluating this SIP submission and will 

act on it in a separate rulemaking. 

Accordingly, in this action, the EPA is 

not addressing the NNSR control 

requirements that apply to major 

stationary sources of direct PM2.5 and 

PM2.5 precursors in the SJV under CAA 

section 189(e). 

F. Demonstration That Attainment by 

Moderate Area Attainment Date Is 

Impracticable 

1. Requirements for Attainment/ 

Impracticability of Attainment 

Demonstrations 

Section 189(a)(1)(B) of the CAA 

requires that each Moderate area 

attainment plan include a 

demonstration that the plan provides for 

attainment by the applicable Moderate 

area attainment date or, alternatively, 

that attainment by such date is 

impracticable. This provision explicitly 

requires that a demonstration of 

attainment be based on air quality 

modeling but does not require such 

modeling for an impracticability 

demonstration. Although the EPA 

expects that most impracticability 

demonstrations will also be supported 

by air quality modeling, it may be 

possible in some cases to support an 

impracticability demonstration with 

ambient PM2.5 data and other relevant 

non-modeling information.154

Section 188(c) of the CAA states, in 

relevant part, that the Moderate area 

attainment date ‘‘shall be as 

expeditiously as practicable but no later 

than the end of the sixth calendar year 

after the area’s designation as 

nonattainment . . . .’’ For the SJV, 

which was initially designated as 

nonattainment for the 2012 PM2.5

standard effective April 15, 2015, the 

applicable Moderate area attainment 

date under section 188(c) for this 

standard is as expeditiously as 

practicable but no later than December 

31, 2021. 

In SIP submissions that demonstrate 

impracticability, the state should 

document how its required control 

strategy in the attainment plan 

represents the application of RACM/ 

RACT and additional reasonable 

measures, at minimum, to existing 

sources. The EPA believes it is 

appropriate to require adoption of all 

available control measures that are 

reasonable, i.e., technologically and 

economically feasible, in areas that do 

not demonstrate timely attainment, even 

where those measures cannot be 

implemented within the 4-year 

timeframe for implementation of 

RACM/RACT under CAA section 

189(a)(1)(C). The impracticability 

demonstration will then be based on a 

showing that the area cannot attain by 

the applicable attainment date, 

notwithstanding implementation of the 

required controls. 

2. Summary of State’s Impracticability 

Demonstration 

The 2016 PM2.5 Plan includes a 

demonstration, based on air quality 

modeling, that even with the 

implementation of RACM/RACT and 

additional reasonable measures for all 

appropriate sources, attainment by 

December 31, 2021, is not practicable. 

The impracticability demonstration is 

included in Appendix A of the 2016 

PM2.5 Plan. As described in section 

IV.C.2 of this proposed rule, the 

projected 2021 control scenario design 

value is 14.8 mg/m3 at Bakersfield-Planz, 

which is typically the monitoring site 

that records the highest PM2.5 levels in 

the SJV. 

As further described in section IV.C.2 

of this proposed rule, the 2018 PM2.5

Plan includes a modeled demonstration 

that projects annual PM2.5

concentrations in 2020 that provides 

additional information on which to 

judge the practicability of attaining by 

2021 in that it is the closest analysis 

year available and represents modeling 

based on updated data. These 

projections lend support for the 2016 

PM2.5 Plan conclusion that the 2012 

annual PM2.5 standard will not be met 

in the SJV in 2021. 

Table 3 shows the projected annual 

PM2.5 concentrations at the four PM2.5

monitoring sites in the SJV that are 

equipped with comprehensive 

particulate matter species 

characterization, as well as BakersfieldPlanz, given that it is the site with the 

highest annual PM2.5 concentrations in 

the base year and projected future year. 

From the 2016 PM2.5 Plan, the 

projections are for 2021 (latest 

permissible Moderate area attainment 

year); from the 2018 PM2.5 Plan, the 

projections are for 2020 (the analysis 

year closest to 2021). 

TABLE 3—PROJECTED ANNUAL PM2.5 CONCENTRATIONS AT SELECTED MONITORING SITES IN THE SAN JOAQUIN VALLEY

[μg/m3] 

Site location 

2016 PM2.5 Plan 2018 PM2.5 Plan 

2013 2021 Difference 

(2013–2021) 2013 2020 Difference (2013–2021) 

Bakersfield-Planz ..................................... 17.3 14.8 ¥2.5 17.2 14.6 ¥2.6 

Bakersfield-California Ave ........................ 16.0 13.6 ¥2.4 16.0 13.5 ¥2.5 

Visalia North Church ................................ 16.2 13.7 ¥2.5 16.2 13.5 ¥2.7 

Fresno-Garland ........................................ 15.0 12.9 ¥2.1 15.0 12.4 ¥2.6 

Modesto-14th St ....................................... 13.0 11.2 ¥1.8 13.0 11.0 ¥2.0 

Sources: 2016 PM2.5 Plan, Table 2–2, and 2018 PM2.5 Plan, App. K, Table 25. 

3. EPA Evaluation and Proposed Action 

The impracticability demonstration in 

the 2016 PM2.5 Plan is based on air 

quality modeling that is generally 

consistent with applicable EPA 

guidance. We find the modeling 

adequate to support the impracticability 

demonstration in the plan, as discussed 

in section IV.C.3 of this notice. 

Similarly, the attainment modeling 

demonstration in the 2018 PM2.5 Plan is 

generally consistent with applicable 

EPA guidance and provides additional 

support that it is impracticable to attain 

the 2012 PM2.5 NAAQS by 2021. 

We have also evaluated the State’s 

control measure demonstration, which 

relies on its BACM/MSM 


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155EPA design value workbook dated May 24, 

2021, ‘‘pm25_designvalues_2018_2020_final_05_

24_21.xlsx,’’ worksheets ‘‘Table 1a’’ and ‘‘Table 5a.’’ 

The certified design value includes all available 

data; no data flagged for exceptional events have 

been excluded. The EPA’s Air Quality System 

(AQS) contains ambient air pollution data collected 

by federal, state, local, and tribal air pollution 

control agencies from thousands of monitors. More 

information is available at: https://www.epa.gov/ 

aqs. See also EPA, 2010–2020 AQS Design Value 

Report, AMP480, June 30, 2021. 

156Concentrations at all 17 monitors in the SJV 

with data spanning 2018 to 2020 are significantly 

higher in 2018 and 2020 relative to concentrations 

in 2019, possibly due to the wildfires in those years. 

86 FR 38652, 38665, Table 5 (July 22, 2021) 

(proposed rule on the 2018 PM2.5 Plan for the 1997 

annual PM2.5 NAAQS of 15.0 mg/m3). 

Notwithstanding the potential effect of wildfires, 

ambient PM2.5 levels in the SJV remain well above 

the 2012 PM2.5 NAAQS standard of 12.0 mg/m3. 

157 59 FR 41998, 42015. 

158 Id. 

159 Id. 

160 Id. 

161 40 CFR 51.1012(a) and 59 FR 41998, 42016. 

162 Id. 

demonstration, as updated by the 2018 

PM2.5 Plan, and find that it provides for 

the expeditious implementation of all 

RACM/RACT and additional reasonable 

measures that may feasibly be 

implemented at this time, consistent 

with the requirements of CAA sections 

172(c)(1) and 189(a)(1)(C) for the 2012 

PM2.5 NAAQS in the SJV, as discussed 

in section IV.D of this notice. 

Finally, we have reviewed available 

monitored data to assess the 

practicability of attaining by 2021. 

Specifically, the certified 2018–2020 

annual average design value for SJV is 

17.6 mg/m3 (at Bakersfield-Planz), with 

exceedances of the 12.0 mg/m3 standard 

throughout the area.155 We note that the 

SJV may have experienced higher than 

normal PM2.5 concentrations in 2018 

and 2020 due to wildfires in the 

surrounding areas during the summer 

and fall months.156 This monitored data 

similarly supports the State’s 

demonstration that it is impracticable to 

attain the 2012 PM2.5 NAAQS by the 

end of 2021. 

Based on this evaluation, we propose 

to approve the State’s demonstration in 

the 2016 PM2.5 Plan that attainment of 

the 2012 PM2.5 NAAQS in the SJV by 

the Moderate area attainment date of 

December 31, 2021, is impracticable, 

consistent with the requirements of 

CAA section 189(a)(1)(B)(ii). On this 

basis, we also propose to reclassify the 

SJV as a Serious nonattainment area, 

which would trigger requirements for 

the State to submit a Serious area 

attainment plan consistent with the 

requirements of subparts 1 and 4 of part 

D, title I of the Act (as described in 

section V of this notice). 

G. Reasonable Further Progress and 

Quantitative Milestones 

1. Requirements for Reasonable Further 

Progress and Quantitative Milestones 

Section 172(c)(2) of the CAA states 

that all nonattainment area plans shall 

require RFP. In addition, CAA section 

189(c) requires that all PM2.5

nonattainment area plans include 

quantitative milestones that the state 

must achieve every three years until the 

area is redesignated to attainment and 

that demonstrate RFP. Section 171(1) 

defines RFP as ‘‘such annual 

incremental reductions in emissions of 

the relevant air pollutant as are required 

by [Part D] or may reasonably be 

required by the Administrator for the 

purpose of ensuring attainment of the 

applicable [NAAQS] by the applicable 

date.’’ Neither subpart 1 nor subpart 4 

of part D, title I of the Act requires a set 

percentage of emission reductions that 

states must achieve in any given year for 

purposes of satisfying the RFP 

requirement. 

For purposes of the PM2.5 NAAQS, the 

EPA has interpreted the RFP 

requirement to require that 

nonattainment area plans show annual 

incremental emission reductions 

sufficient to maintain generally linear 

progress toward attainment by the 

applicable deadline.157 As discussed in 

the EPA’s guidance in the General 

Preamble Addendum,158 requiring 

linear progress in reductions of direct 

PM2.5 and any individual precursor in a 

PM2.5 plan may be appropriate in the 

following situations: 

• The pollutant is emitted by a large 

number and range of sources, 

• the relationship between any 

individual source or source category 

and overall air quality is not well 

known, 

• a chemical transformation is 

involved (e.g., secondary particulate 

contributes significantly to PM2.5 levels 

over the standard), and/or 

• the emission reductions necessary 

to attain the PM2.5 standard are 

inventory-wide.159

The General Preamble Addendum 

indicates that requiring linear progress 

may be less appropriate in other 

situations, such as in situations where: 

• there are a limited number of 

sources of direct PM2.5 or a precursor, 

• the relationships between 

individual sources and air quality are 

relatively well defined, and/or 

• the emission control systems 

utilized (e.g., at major point sources) 

will result in a swift and dramatic 

emission reductions. 

In nonattainment areas characterized 

by any of these latter conditions, RFP 

may be better represented as stepwise 

progress as controls are implemented 

and achieve significant reductions soon 

thereafter. For example, if an area’s 

nonattainment problem can be 

attributed to a few major sources, the 

EPA’s guidance indicates that ‘‘RFP 

should be met by ‘adherence to an 

ambitious compliance schedule’ which 

is likely to periodically yield significant 

emission reductions of direct PM2.5 or a 

PM2.5 precursor.’’ 160

Attainment plans for the PM2.5

NAAQS must include detailed 

schedules for compliance with emission 

regulations in the nonattainment area 

and provide corresponding emissions 

projections for each applicable 

milestone year that represent generally 

linear or stepwise progress in reducing 

emissions on an annual basis.161 In 

reviewing an attainment plan under 

subpart 4, the EPA considers whether 

the annual incremental emission 

reductions to be achieved are reasonable 

in light of the statutory objective of 

timely attainment. Although early 

implementation of the most costeffective control measures is often 

appropriate, states should consider both 

cost-effectiveness and pollution 

reduction effectiveness when 

developing implementation schedules 

for control measures and may 

implement measures that are more 

effective at reducing PM2.5 earlier to 

provide greater public health 

benefits.162

The PM2.5 SIP Requirements Rule 

establishes specific regulatory 

requirements for purposes of satisfying 

the Act’s RFP requirements and 

provides related guidance in the 

preamble to the rule. Specifically, under 

the PM2.5 SIP Requirements Rule, each 

PM2.5 attainment plan must contain an 

RFP analysis that includes, at a 

minimum, the following four 

components: (1) An implementation 

schedule for control measures; (2) RFP 

projected emissions for direct PM2.5 and 

all PM2.5 plan precursors for each 

applicable milestone year, based on the 

anticipated control measure 

implementation schedule; (3) a 

demonstration that the control strategy 

and implementation schedule will 

achieve reasonable progress toward 

attainment between the base year and 

the attainment year; and (4) a 

demonstration that by the end of the 

calendar year for each milestone date for 

the area, pollutant emissions will be at 

levels that reflect either generally linear 

progress or stepwise progress in 

reducing emissions on an annual basis 

between the base year and the 


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163 40 CFR 51.1012(a). 

164 81 FR 58010, 58056. 

165 Id. at 58056, 58057. 

166 General Preamble Addendum, 42016–42017. 

167 General Preamble, 13539 and General 

Preamble Addendum, 42016. 

168 40 CFR 51.1013(a)(1). 

169 80 FR 2206. 

170 General Preamble Addendum, 42016. 

171 2016 PM2.5 Plan, Table 3–6. We note that 

Appendix B (‘‘Emissions Inventory’’) of the plan 

indicates that emissions of ammonia, SOX, and VOC 

will also generally decline from the 2013 base year, 

but the RFP plan does not address these three 

precursor pollutants given the State’s conclusion 

that they do not contribute significantly to PM2.5

levels that exceed the 2012 PM2.5 NAAQS in the 

SJV. 2016 PM2.5 Plan, 3–10. 

172 2016 PM2.5 Plan, App. B. 

173Table 3–6 identifies only emission levels for 

milestone years that must be addressed by the 

Moderate area plan (i.e., 2019 and 2022). 

174 2016 PM2.5 Plan, 3–10, and CARB 2016 Staff 

Report, 13. 

175 2016 PM2.5 Plan, 3–5 through 3–7; see also 

evaluation of RACM/RACT and additional 

reasonable control measures in section IV.D of this 

proposed rule. 

attainment year.163 States should 

estimate the RFP projected emissions for 

each quantitative milestone year by 

sector on a pollutant-by-pollutant 

basis.164 In an area that cannot 

practicably attain the PM2.5 standard by 

the applicable Moderate area attainment 

date, full implementation of a control 

strategy that satisfies the Moderate area 

control requirements represents RFP 

towards attainment.165

Section 189(c) requires that 

attainment plans include quantitative 

milestones that demonstrate RFP. The 

purpose of the quantitative milestones is 

to allow for periodic evaluation of the 

area’s progress towards attainment of 

the NAAQS consistent with RFP 

requirements. Because RFP is an annual 

emission reduction requirement and the 

quantitative milestones are to be 

achieved every three years, when a state 

demonstrates compliance with the 

quantitative milestone requirement, it 

will demonstrate that RFP has been 

achieved during each of the relevant 

three years. Quantitative milestones 

should provide an objective means to 

evaluate progress toward attainment 

meaningfully, e.g., through imposition 

of emission controls in the attainment 

plan and the requirement to quantify 

those required emission reductions. The 

CAA also requires states to submit 

milestone reports (due 90 days after 

each milestone), and these reports 

should include calculations and any 

assumptions made by the state 

concerning how RFP has been met, e.g., 

through quantification of emission 

reductions to date.166 The Act requires 

states to include RFP and quantitative 

milestones even for areas that cannot 

practicably attain. 

The CAA does not specify the starting 

point for counting the three-year periods 

for quantitative milestones under CAA 

section 189(c). In the General Preamble 

and General Preamble Addendum, the 

EPA interpreted the CAA to require that 

the starting point for the first three-year 

period be the due date for the Moderate 

area plan submission.167 Consistent 

with this longstanding interpretation of 

the Act, the PM2.5 SIP Requirements 

Rule requires that each plan for a 

Moderate PM2.5 nonattainment area 

contain quantitative milestones to be 

achieved no later than milestone dates 

4.5 years and 7.5 years from the date of 

designation of the area.168 Because the 

EPA designated the SJV nonattainment 

for the 2012 PM2.5 NAAQS effective 

April 15, 2015,169 the applicable 

quantitative milestone dates for 

purposes of this NAAQS in the SJV are 

October 15, 2019, and October 15, 2022. 

Following reclassification of the SJV as 

Serious for the 2012 PM2.5 standard, 

later milestones would be addressed by 

the Serious area plan.170

2. Summary of State’s Reasonable 

Further Progress Demonstrations and 

Quantitative Milestones 

a. 2016 PM2.5 Plan RFP and Quantitative 

Milestones 

The RFP demonstration and 

quantitative milestones are discussed in 

section 3.5 of the 2016 PM2.5 Plan. The 

plan estimates that emissions of direct 

PM2.5 and NOX will generally decline 

from the 2013 base year and states that 

emissions of each of these pollutants 

will remain at or below the levels 

needed to show ‘‘generally linear 

progress’’ through 2022, the Moderate 

area post-attainment milestone year for 

the 2012 PM2.5 NAAQS.171 The Plan’s 

emissions inventory shows that direct 

PM2.5 and NOX are emitted by a large 

number and range of sources in the SJV 

and that the emission reductions needed 

for these pollutants are inventorywide.172 The Plan states that all RACM 

and RACT for stationary, area, and 

mobile sources have been identified and 

adopted, and identifies the District rules 

achieving emission reductions post2013 in Table 3–2 and CARB regulations 

contributing to attainment in Table 3–3. 

Table 3–6 of the 2016 PM2.5 Plan 

presents target RFP emission levels, 

based on linear emission reductions 

from 2013 through 2022, and the RFP 

projected emissions, based on the plan’s 

baseline emissions inventory and 

control strategy (i.e., RACM/RACT and 

additional reasonable measures) for 

each quantitative milestone year (2019 

and 2022).173 We reproduce Table 3–6, 

in part, along with the plan’s 2013 base 

year inventory from Table 3–5, in Table 

4. Based on these analyses, the District 

and CARB conclude that their adopted 

control strategy will achieve sufficient 

reductions in emissions of direct PM2.5

and NOX to result in emission levels at 

or below the RFP and quantitative 

milestone target emission levels for 

2019 and 2022.174

TABLE 4—2016 PM2.5 PLAN: ANNUAL PM2.5 EMISSIONS INVENTORY FOR BASE YEAR AND MODERATE AREA PLAN

MILESTONE YEARS

[Annual average, tpd] 

Pollutant 2013 baseline 2019 RFP target 

emissions level 

2019 projected 

emissions level 

2022 RFP target 

emissions level 

2022 projected 

emissions level 

Direct PM2.5 ..................................................... 63.4 60.8 60.2 59.5 59.5 

NOX .................................................................. 318.1 229.5 219.4 185.2 185.2 

Source: 2016 PM2.5 Plan, tables 3–5 and 3–6. We corrected the 2019 RFP Target Emissions Level for NOX in Table 3–6 to reflect the value 

in Table 3–5 that was transcribed incorrectly as 229.1 tpd. 

The 2016 PM2.5 Plan documents the 

State’s conclusion that all RACM/RACT 

and additional reasonable measures for 

these pollutants are being implemented 

as expeditiously as practicable and 

identifies projected levels of direct 

PM2.5 and NOX emissions that reflect 

full implementation of the State, 

District, and SJV MPOs’ RACM/RACT 

and additional reasonable measure 

control strategy for these pollutants.175

The control strategy that provides the 

basis for these emission projections is 

described in attachments 1 and 2 of the 

2016 PM2.5 Plan. 


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176 2016 PM2.5 Plan, 3–13. 

177Appendix H to 2018 PM2.5 Plan, submitted 

February 11, 2020, via the EPA State Planning 

Electronic Collaboration System. This revised 

version of Appendix H replaces the version 

submitted with the 2018 PM2.5 Plan on May 10, 

2019. All references to Appendix H in this 

proposed rule are to the revised version of 

Appendix H submitted February 11, 2020. 

178 2018 PM2.5 Plan, App. H, H–1. 

179 Id. at H–23 to H–24 (for State milestones) and 

H–20 to H–21 (for District milestones). 

180 2018 PM2.5 Plan, App. H, H–4 to H–15. 

181CARB Resolution 18–49 (October 25, 2018), 5; 

2018 PM2.5 Plan, Ch. 4, Table 4–8; email dated 

November 12, 2019, from Sylvia Vanderspek, CARB 

to Anita Lee, EPA Region IX, ‘‘RE: SJV PM2.5

information’’ (attaching ‘‘Valley State SIP Strategy 

Progress’’); CARB 2018 Staff Report, 14; SJVUAPCD 

Governing Board Resolution 18–11–16 (November 

15, 2018), 10–11; 2018 PM2.5 Plan, Ch. 4, tables 4– 

4 and 4–5; and email dated November 12, 2019, 

from Jon Klassen, SJVUAPCD to Wienke Tax, EPA 

Region IX, ‘‘RE: follow up on aggregate 

commitments in SJV PM2.5 plan’’ (attaching 

‘‘District Progress In Implementing Commitments 

with 2018 PM2.5 Plan’’). 

182 2018 PM2.5 Plan, Ch. 4, Table 4–3 (‘‘Emission 

Reductions from District Measures’’) and Table 4– 

9 (‘‘San Joaquin Valley Expected Emission 

Reductions from State Measures’’). 

183 2018 PM2.5 Plan, App. H, H–4 to H–10 

(describing commitments by CARB and SJVUAPCD 

to adopt additional measures to fulfill tonnage 

commitments for 2024 and 2025, including 

‘‘action’’ and ‘‘implementation’’ dates occuring 

before 2024 to ensure expeditious progress toward 

attainment). 

184 2018 PM2.5 Plan, App. H, H–20. 

185 Id. at Ch. 4, 4–12 (Table 4–4). See also email 

dated November 12, 2019, from Jon Klassen, 

SJVUAPCD to Wienke Tax, EPA Region IX, ‘‘RE: 

follow up on aggregate commitments in SJV PM2.5

plan’’ (attaching ‘‘District Progress In Implementing 

Commitments with 2018 PM2.5 Plan,’’ stating the 

District’s intent to take action on the listed rules 

and measures by beginning the public process on 

each measure and then proposing the rule or 

measure to the SJVUAPCD Governing Board). 

186 Id. at H–23. 

187 Id. at 4–28 (Table 4–8). See also email dated 

November 12, 2019, from Sylvia Vanderspek, CARB 

to Anita Lee, EPA Region IX, ‘‘RE: SJV PM2.5

information’’ (attaching ‘‘Valley State SIP Strategy 

Progress’’) and CARB 2018 Staff Report, 14–15 

(stating CARB’s intent to ‘‘bring to the Board or take 

action on the list of proposed State measures for the 

Valley’’ by the action dates specified in Table 2). 

188 2018 PM2.5 Plan, App. H, H–20. 

For quantitative milestones, the 2016 

PM2.5 Plan identifies 2019 and 2022 as 

the applicable milestone years and 

includes milestones to track the State’s 

and District’s implementation of control 

measures and to document updated 

emissions data.176 For 2019, the 

milestone includes a ‘‘list of measures 

in the SIP control strategy and key 

implementation requirements,’’ 

including compliance milestones in 

CARB’s Truck and Bus Regulation and 

in the District’s Rule 4901 on residential 

wood burning. For 2022, the milestone 

includes a ‘‘list of measures in the SIP 

control strategy and key implementation 

requirements,’’ including compliance 

milestones in CARB’s Truck and Bus 

Regulation. 

b. 2018 PM2.5 Plan RFP and Quantitative 

Milestones 

Appendix H of the 2018 PM2.5 Plan 

provides the State’s updated RFP 

demonstration and quantitative 

milestones, based on updated data (e.g., 

updated emissions inventories, as 

discussed in section IV.A of this 

proposed rule) for the 2019 and 2022 

milestone years. Following the 

identification of a transcription error in 

the RFP tables of Appendix H, the State 

submitted a revised version of 

Appendix H that corrects the 

transcription error and provides 

additional information on the RFP 

demonstration.177 Given the State’s 

conclusions that ammonia, SOX, and 

VOC emissions do not contribute 

significantly to PM2.5 levels that exceed 

the 2012 PM2.5 NAAQS in the SJV, as 

discussed in section IV.B of this 

proposed rule, the RFP demonstration 

provided by the State addresses 

emissions of direct PM2.5 and NOX.178

Similarly, the State developed 

quantitative milestones based upon the 

2018 PM2.5 Plan’s strategy for reducing 

emissions of direct PM2.5 and NOX.179

Like the 2016 PM2.5 Plan, the 2018 

PM2.5 Plan estimates that emissions of 

direct PM2.5 and NOX will generally 

decline from the 2013 base year to the 

2022 RFP milestone year and beyond, 

and that direct PM2.5 and NOX are 

emitted by a large number and range of 

sources in the SJV. The 2018 PM2.5 Plan 

relies on the same set of identified 

control measures as the 2016 PM2.5 Plan 

to demonstrate RFP through 2022, i.e., 

the baseline measures reflected in each 

plan’s emissions inventory.180

In addition to these baseline 

measures, the 2018 PM2.5 Plan’s control 

strategy includes specific control 

measure commitments for purposes of 

attaining the 2012 PM2.5 NAAQS by 

2025, including commitments by the 

State and District to develop and 

propose to their respective boards 

specific regulatory and incentive-based 

measures identified in the plan by 

specific years leading up to 2025, 

including 2019 and 2022.181 Although 

the attainment demonstration does not 

rely on these control measure 

commitments for emission reductions 

until 2024,182 the RFP and quantitative 

milestone elements of the 2018 PM2.5

Plan rely on these control measure 

commitments to demonstrate that the 

plan requires RFP toward attainment.183

Specifically, for the 2019 milestone 

year, Appendix H of the 2018 PM2.5 Plan 

describes the District’s quantitative 

milestone as a report on ‘‘[t]he status of 

SIP measures adopted between 2017 

and 2019 as per the schedule included 

in the adopted Plan, including 

Residential Wood Burning Strategy and 

Commercial Under-Fired Charbroiler 

incentive-based strategy.’’ 184 The 

schedule for development of new or 

revised SIP measures is in Chapter 4 of 

the 2018 PM2.5 Plan and identifies an 

‘‘action date’’ between 2017 and 2019 

for one District measure: ‘‘Rule 4901, 

Wood Burning Fireplaces and Wood 

Burning Heaters (Hot-spot Strategy).’’ 185

Appendix H describes CARB’s 

quantitative milestones as a report on 

three measure-specific milestones: (1) 

Actions taken between 2017 and 2019 to 

implement the Truck and Bus 

Regulation that required particulate 

filters and cleaner engine standards on 

existing heavy-duty diesel trucks and 

buses in California; (2) implementation 

of the ‘‘In-Use Off-Road Diesel-Fueled 

Fleets Regulation’’ (the ‘‘Off-Road 

Regulation’’) that began in 2014 for large 

fleets and in 2017 for medium fleets and 

limited emissions from existing off-road 

diesel vehicles operated in California; 

and (3) the ‘‘status of SIP measures 

adopted between 2017 and 2019, 

including the California Low-NOX

Engine Standard for new on-road heavyduty engines used in medium- and 

heavy-duty trucks purchased in 

California.’’ 186 The schedule for 

development of new or revised CARB 

measures is in Chapter 4 of the 2018 

PM2.5 Plan and identifies ‘‘action’’ dates 

between 2017 and 2019 for eight CARB 

measures: ‘‘Lower Opacity Limits for 

Heavy-Duty Vehicles,’’ ‘‘Amended 

Warranty Requirements for Heavy-Duty 

Vehicles,’’ the ‘‘Low-NOX Engine 

Standard,’’ ‘‘Innovative Clean Transit,’’ 

‘‘Advanced Clean Local Trucks (Last 

Mile Delivery),’’ ‘‘Zero-Emission Airport 

Shuttle Buses,’’ ‘‘Zero-Emission Airport 

Ground Support Equipment,’’ and 

‘‘Transport Refrigeration Units Used for 

Cold Storage.’’ 187

For the 2022 milestone year, 

Appendix H of the 2018 PM2.5 Plan 

describes the District’s quantitative 

milestone as a report on ‘‘[t]he status of 

SIP measures adopted between 2019 

and 2022 as per the schedule included 

in the adopted Plan, including 

Residential Wood Burning Strategy and 

Commercial Under-Fired Charbroiler 

incentive-based strategy.’’ 188 The 

schedule for development of new or 

revised SIP measures in the 2018 PM2.5

Plan identifies ‘‘action dates’’ between 

2019 and 2022 for 12 District measures 

listed in tables 4–4 and 4–5 of Chapter 

4, including, for example, ‘‘Rule 4311, 

Flares,’’ ‘‘Rule 4702, Internal 

Combustion Engines,’’ and ‘‘Rule 4354, 


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189 Id. at Ch. 4, 4–12 and 4–13 (tables 4–4 and 4– 

5). See also email dated November 12, 2019, from 

Jon Klassen, SJVUAPCD to Wienke Tax, EPA 

Region IX, ‘‘RE: follow up on aggregate 

commitments in SJV PM2.5 plan’’ (attaching 

‘‘District Progress In Implementing Commitments 

with 2018 PM2.5 Plan,’’ stating the District’s intent 

to take action on the listed rules and measures by 

beginning the public process on each measure and 

then proposing the rule or measure to the 

SJVUAPCD Governing Board). 

190 Id. at 4–28 (Table 4–8). See also email dated 

November 12, 2019, from Sylvia Vanderspek, CARB 

to Anita Lee, EPA Region IX, ‘‘RE: SJV PM2.5

information’’ (attaching ‘‘Valley State SIP Strategy 

Progress’’) and CARB 2018 Staff Report, 14–15 

(stating CARB’s intent to ‘‘bring to the Board or take 

action on the list of proposed State measures for the 

Valley’’ by the action dates specified in Table 2). 

191 2018 PM2.5 Plan, App. H, Table H–12. 

192 2018 PM2.5 Plan, App. D, Ch. IV, and App. C. 

193The RACM/RACT and additional reasonable 

measures control strategy that provides the basis for 

the RFP demonstration is described in attachments 

1 and 2 of the 2016 PM2.5 Plan. 

Glass Melting Furnaces.’’ 189 Appendix 

H describes CARB’s quantitative 

milestone as a report on two measurespecific milestones: (1) Actions taken 

between 2019 and 2022 to implement 

the Truck and Bus Regulation that 

required particulate filters and cleaner 

engine standards on existing heavy-duty 

diesel trucks and buses in California, 

and (2) the ‘‘status of SIP measures 

adopted between 2019 and 2022, 

including Advanced Clean Cars 2 and 

the Heavy-Duty Vehicle Inspection and 

Maintenance Program.’’ The schedule 

for development of new or revised 

CARB measures in the 2018 PM2.5 Plan 

identifies ‘‘action’’ dates between 2019 

and 2022 for 13 CARB measures listed 

in Table 4–8 of Chapter 4, including, for 

example, the ‘‘Heavy-Duty Vehicle 

Inspection and Maintenance Program,’’ 

‘‘Small Off-Road Engines,’’ and the 

‘‘Low-Emission Diesel Fuel 

Requirement.’’ 190

Appendix H of the 2018 PM2.5 Plan 

identifies October 15, 2019, and October 

15, 2022, as applicable milestone dates 

for the 2012 PM2.5 NAAQS.191 Table H– 

11 in Appendix H presents the RFP 

projected emissions levels for 2019 and 

2022, based on the plan’s emissions 

inventory and baseline measures. We 

reproduce Table H–11, in part, along 

with the 2018 PM2.5 Plan’s base year 

inventory for 2013 from Appendix B, in 

Table 5. 

TABLE 5—2018 PM2.5 PLAN: ANNUAL PM2.5 EMISSIONS INVENTORY FOR BASE YEAR AND MODERATE AREA PLAN

MILESTONE YEARS

[Annual average, tpd] 

Pollutant 2013 Base year 

2019 RFP target 

emissions 

level a

2019 projected 

emissions level 

2022 RFP target 

emissions level 

2022 projected 

emissions level 

Direct PM2.5 ..................................................... 62.5 59.2 59.2 58.4 58.4 

NOX .................................................................. 317.2 214.5 214.5 179.8 179.8 

Source: 2018 PM2.5 Plan, App. B, tables B–1 and B–2, and App. H, Table H–11. 

The majority of the NOX and PM2.5

reductions from 2013 to 2019 and 2022 

result from CARB’s current mobile 

source control program, which provides 

significant ongoing reductions in 

emissions of direct PM2.5 and NOX from 

on-road and non-road mobile sources, 

such as light duty vehicles, heavy-duty 

trucks and buses, non-road equipment, 

and fuels. The District has also adopted 

numerous stationary and area source 

rules for direct PM2.5 and NOX emission 

sources that are projected to contribute 

to RFP towards attainment of the PM2.5

standards. These include control 

measures for stationary internal 

combustion engines, residential 

fireplaces and woodstoves, glass 

manufacturing facilities, agricultural 

burning sources, and various sizes of 

boilers, steam generators, and process 

heaters used in industrial operations. 

CARB’s mobile source BACM and MSM 

analysis in Appendix D of the 2018 

PM2.5 Plan and the District’s stationary 

and area source BACM and MSM 

analysis in Appendix C of the 2018 

PM2.5 Plan provide a more 

comprehensive overview of each of 

these programs and regulations, among 

many others.192

3. EPA Evaluation and Proposed Action 

a. Reasonable Further Progress 

The EPA has evaluated the RFP 

demonstrations in the 2016 PM2.5 Plan 

and 2018 PM2.5 Plan (Appendix H) and 

proposes to find that they satisfy the 

statutory and regulatory requirements 

for RFP. Because the RFP demonstration 

in Appendix H of the 2018 PM2.5 Plan 

is based on updated emissions data and 

updated information about the control 

strategies being implemented in the SJV, 

we focus our evaluation on Appendix H 

of the 2018 PM2.5 Plan. 

First, the 2016 PM2.5 Plan and 2018 

PM2.5 Plan document the State’s, 

District’s, and MPOs’ conclusions that 

they are implementing all RACM/RACT 

and additional reasonable measures for 

direct PM2.5 and NOX emissions in the 

SJV as expeditiously as practicable.193

The 2018 PM2.5 Plan also identifies the 

State’s and District’s schedules for 

developing and proposing certain new 

or revised control measures listed in 

their respective control measure 

commitments. These schedules are 

found in tables 4–4, 4–5, and 4–8 of the 

2018 PM2.5 Plan and in Table H–2 of 

Appendix H. 

Second, the RFP demonstration 

contains projected emission levels for 

direct PM2.5 and NOX for each 

applicable milestone year. These 

projections are based on continued 

implementation of the existing control 

measures in the area (i.e., baseline 

measures) and reflect full 

implementation of the State, District, 

and MPOs’ RACM/RACT and additional 

reasonable measures control strategy for 

these pollutants. 

As shown in tables 4 and 5 of this 

proposed rule, the projected RFP 

emission levels in each plan for 2019 

and 2022 are equal to the target RFP 

emission levels in 2019 and 2022, 

respectively. We note that the 2013 base 

year emissions in the 2018 PM2.5 Plan’s 

emissions inventory are 0.9 tpd lower 

for both direct PM2.5 and NOX compared 

to the base year emissions in the 2016 

PM2.5 Plan’s emissions inventory, and 

that the 2018 PM2.5 Plan’s projected RFP 

emission levels for the 2019 and 2022 

milestone years represent emission 

reductions that exceed those of the 2016 

PM2.5 Plan’s projected RFP levels by 0.1 

tpd direct PM2.5 and 4.0 tpd NOX in 

2019, and by 0.2 tpd direct PM2.5 and 

4.5 tpd NOX in 2022. In other words, the 

2018 PM2.5 Plan’s RFP demonstration 

indicates a slightly faster pace of 

emission reductions relative to those in 

the 2016 PM2.5 Plan’s RFP 

demonstration, and thus represents a 

slightly more stringent RFP 

demonstration than that in the 2016 


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194The EPA is excluding the ‘‘Advanced Clean 

Cars 2’’ measure from the milestones because this 

measure is scheduled for implementation in 2026, 

well after both the 2022 post-attainment RFP 

milestone year and the projected 2025 attainment 

year for the 2012 PM2.5 NAAQS in the 2018 PM2.5

Plan. Valley State SIP Strategy, Table 7. 

195Letter dated January 13, 2020, from Richard 

W. Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX, with 

enclosures. 

196 40 CFR 51.1014(a). 

197 81 FR 58010, 58066 and General Preamble 

Addendum, 42015. 

198 81 FR 58010, 58067. 

PM2.5 Plan. These projected emissions 

levels demonstrate that the RACM/ 

RACT and additional reasonable 

measures control strategy in the 2016 

PM2.5 Plan will achieve RFP toward 

attainment. 

Finally, the RFP demonstration shows 

that overall pollutant emissions in each 

milestone year will be at levels that 

reflect generally linear progress toward 

attainment. The RFP target emissions 

levels for 2019 and 2022 identified in 

both the 2016 PM2.5 Plan and the 2018 

PM2.5 Plan reflect consistent progress in 

emission reductions from the 2013 base 

year to the 2022 post-attainment 

milestone year for the 2012 PM2.5

NAAQS, based on the implementation 

of the RACT/RACT and additional 

reasonable measures control strategy. 

For these reasons, we propose to 

determine that the 2016 PM2.5 Plan, as 

revised and supplemented by Appendix 

H of the 2018 PM2.5 Plan, satisfies the 

requirements for RFP in CAA section 

172(c)(2) and 40 CFR 51.1012 for the 

2012 PM2.5 NAAQS in the SJV. 

b. Quantitative Milestones 

The 2016 PM2.5 Plan identifies the 

appropriate years (2019 and 2022) for 

quantitative milestones and Appendix H 

of the 2018 PM2.5 Plan identifies specific 

quantitative milestone dates (i.e., 

October 15, 2019, and October 15, 2022) 

that are consistent with the 

requirements of 40 CFR 51.1013(a)(4). 

Both plans also identify the target 

emission levels for direct PM2.5 and 

NOX to be achieved by these milestone 

dates through implementation of the 

control strategy. Finally, Appendix H of 

the 2018 PM2.5 Plan identifies 

commitments by the State and the 

District to develop and propose new or 

revised control measures on a fixed 

timeframe, for purposes of attaining the 

2012 PM2.5 NAAQS as expeditiously as 

practicable. These target emission levels 

and associated control requirements, 

together with the State’s and District’s 

commitments to develop and propose 

new or revised control measures on a 

fixed timeframe, provide for objective 

evaluation of the area’s progress towards 

attainment of the 2012 PM2.5 NAAQS. 

The State’s quantitative milestones in 

Appendix H are to implement specific 

baseline measures identified in the plan 

(i.e., the Truck and Bus Regulation and 

the Off-Road Regulation) and to develop 

and propose several new or revised 

measures listed in the State’s control 

measure commitments that apply to 

heavy-duty trucks and buses and nonroad equipment sources.194 These 

commitments to develop and propose 

additional direct PM2.5 and NOX control 

measures for mobile sources are part of 

CARB’s strategy for attaining the 2012 

PM2.5 NAAQS in the SJV. Similarly, the 

District’s quantitative milestones in 

Appendix H are to develop and propose 

several new or revised measures listed 

in the District’s control measure 

commitments that apply to sources such 

as residential wood burning, 

conservation management practices, 

glass melting furnaces, and internal 

combustion engines. These 

commitments to develop and propose 

additional direct PM2.5 and NOX control 

measures for stationary and area sources 

are part of the District’s strategy for 

attaining the 2012 PM2.5 NAAQS in the 

SJV. Thus, the State’s and District’s 

obligations to implement the identified 

baseline control measures and to fulfil 

their respective commitments to 

develop and propose new or revised 

control measures for purposes of 

attaining the 2012 PM2.5 NAAQS 

provide objective means for evaluating 

the SJV’s progress toward timely 

attainment. 

For these reasons, we propose to 

determine that the 2016 PM2.5 Plan, as 

revised and supplemented by Appendix 

H of the 2018 PM2.5 Plan, satisfies the 

requirements for quantitative milestones 

in CAA section 189(c) and 40 CFR 

51.1013 for the 2012 PM2.5 NAAQS in 

the SJV. 

We note that on January 13, 2020, 

CARB submitted the SJV ‘‘2019 

Quantitative Milestone Report for the 

2012 PM2.5 NAAQS’’ (‘‘2019 QM 

Report’’) to the EPA.195 The EPA is 

currently reviewing the SJV 2019 QM 

Report and will determine, as part of its 

action on the submitted report, whether 

the State and District have met their 

identified quantitative milestones for 

2019. 

H. Contingency Measures 

We are presenting our review of the 

SIP submittals for compliance with 

contingency measure requirements in 

two different sections of this document. 

In this section, we present our review of 

the submittals with respect to the 

contingency measure requirements for 

the SJV as a Moderate area for the 2012 

PM2.5 NAAQS for which the state has 

submitted an impracticability 

demonstration. In section VII of this 

document, we present our review of the 

submittals with respect to the 

contingency measure requirements for 

the SJV for the 2006 PM2.5 NAAQS. 

1. Requirements for Contingency 

Measures 

Under CAA section 172(c)(9), states 

required to make an attainment plan SIP 

submission must include contingency 

measures that they will implement if the 

area fails to meet RFP (‘‘RFP 

contingency measures’’) or fails to attain 

the NAAQS by the applicable 

attainment date (‘‘attainment 

contingency measures’’). Under the 

PM2.5 SIP Requirements Rule, states 

must include contingency measures that 

will be implemented following a 

determination by the EPA that the state 

has failed: (1) To meet any RFP 

requirement in the approved SIP; (2) to 

meet any quantitative milestone in the 

approved SIP; (3) to submit a required 

quantitative milestone report; or (4) to 

attain the applicable PM2.5 NAAQS by 

the applicable attainment date.196

Contingency measures must be fully 

adopted rules or control measures that 

are ready to be implemented quickly 

upon failure to meet RFP or failure of 

the area to meet the relevant NAAQS by 

the applicable attainment date.197

The EPA does not interpret the 

requirement for contingency measures 

for failing to attain the NAAQS by the 

applicable attainment date to apply to a 

Moderate area that a state adequately 

demonstrates cannot practicably attain 

the NAAQS by the statutory attainment 

date. Rather, the EPA believes it is 

appropriate for the state to identify and 

adopt these contingency measures in a 

timely way as part of the Serious area 

attainment plan that it will develop 

once the EPA reclassifies such an area. 

However, if a state with a Moderate area 

that the EPA has found cannot 

practicably attain the NAAQS by the 

attainment date fails to meet RFP, when 

reviewed as part of the quantitative 

milestone either 4.5 or 7.5 years after 

designation, then the requirement to 

implement contingency measures would 

be triggered as required by CAA section 

172(c)(9).198

The purpose of contingency measures 

is to continue progress in reducing 

emissions while a state revises its SIP to 

meet the missed RFP requirement or to 

correct ongoing nonattainment. Neither 

the CAA nor the EPA’s implementing 

regulations establish a specific level of 


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199 81 FR 58010, 58066. See also General 

Preamble 13512, 13543–13544, and General 

Preamble Addendum, 42014–42015. 

200Bahr v. EPA, 836 F.3d 1218, 1235–1237 (9th 

Cir. 2016). 

201 2016 PM2.5 Plan, 3–13 to 3–17. 

202 2016 PM2.5 Plan, Table 3–8. 

203 2016 PM2.5 Plan, 3–15 and 3–16. See also 2016 

PM2.5 Plan, App. C (‘‘SIP Creditable Incentive-Based 

Emission Reductions’’). 

204 2016 PM2.5 Plan, 3–17. 

205 Id. at Table 3–7. 

emission reductions that 

implementation of contingency 

measures must achieve, but the EPA 

recommends that contingency measures 

should provide for emission reductions 

equivalent to approximately one year of 

reductions needed for RFP in the 

nonattainment area, calculated as the 

overall level of reductions needed to 

demonstrate attainment divided by the 

number of years from the base year to 

the attainment year. In general, we 

expect all actions needed to effect full 

implementation of the measures to 

occur within 60 days after the EPA 

notifies the state of a failure to meet RFP 

or to attain.199

To satisfy the requirements of 40 CFR 

51.1014, the contingency measures 

adopted as part of a PM2.5 attainment 

plan must consist of control measures 

for the area that are not otherwise 

required to meet other attainment plan 

requirements (e.g., to meet RACM/RACT 

requirements) and must specify the 

timeframe within which their 

requirements become effective following 

any of the EPA determinations specified 

in 40 CFR 51.1014(a). In a 2016 decision 

called Bahr v. EPA (‘‘Bahr’’),200 the 

Ninth Circuit Court of Appeals rejected 

the EPA’s interpretation of CAA section 

172(c)(9) to allow approval of alreadyimplemented control measures as 

contingency measures. In Bahr, the 

Ninth Circuit concluded that 

contingency measures must be measures 

that are triggered and implemented only 

after the EPA determines that an area 

fails to meet RFP requirements or to 

attain by the applicable attainment date, 

and the state must not have begun to 

implement such measures before this 

determination is made. Thus, already 

implemented measures cannot serve as 

contingency measures under CAA 

section 172(c)(9). To comply with 

section 172(c)(9), as interpreted in the 

Bahr decision, a state must develop, 

adopt, and submit one or more 

contingency measures to be triggered 

upon a failure to meet any RFP 

requirement, failure to meet a 

quantitative milestone requirement, or 

failure to attain the NAAQS by the 

applicable attainment date regardless of 

the extent to which alreadyimplemented measures would achieve 

surplus emission reductions beyond 

those necessary to meet RFP or 

quantitative milestone requirements and 

beyond those predicted to achieve 

attainment of the NAAQS. 

2. Summary of State’s Contingency 

Measures 

a. 2016 PM2.5 Plan Contingency 

Measures 

The 2016 PM2.5 Plan includes a 

contingency measure element that is 

intended to address a potential failure to 

meet RFP but, consistent with the plan’s 

demonstration that it is impracticable to 

attain the 2012 PM2.5 NAAQS by 

December 31, 2021, that does not 

address a potential failure to attain the 

NAAQS by the applicable attainment 

date.201 Rather, the State and District 

conclude that they intend to identify 

and adopt contingency measures for 

failure to attain as part of the Serious 

area attainment plan (and, in fact, have 

done so in the 2018 PM2.5 Plan). The 

State and District use the plan’s RFP 

analysis through 2022 to calculate the 

amount of direct PM2.5 and NOX

emission reductions that represents one 

year’s worth of RFP. Specifically, the 

State and District divided the difference 

in emissions in 2022 and 2013 by nine 

to estimate one year’s worth of RFP. The 

2016 PM2.5 Plan estimates that one 

year’s worth of RFP is 0.4 tpd of direct 

PM2.5 and 14.8 tpd of NOX.202 The 

contingency measure element does not 

address ammonia, SOX, and VOC in 

light of the State and District’s 

conclusion that each of these three 

pollutants does not contribute 

significantly to exceedances of the 2012 

PM2.5 NAAQS in the SJV. In addition, 

the contingency measure element in the 

2016 PM2.5 Plan only addresses the 

potential failure to meet the 2019 RFP 

milestone, not the potential failure to 

meet the 2022 RFP milestone. 

CARB and the District prepared the 

2016 PM2.5 Plan prior to the Bahr 

decision, and thus did not include any 

contingency measures that would only 

be triggered conditionally and 

prospectively, upon a future failure to 

meet RFP or other relevant event. 

Instead, CARB and the District relied 

only on emissions reductions from 

already-implemented measures to 

satisfy the contingency measure 

requirement. To demonstrate sufficient 

reductions for contingency purposes, 

the 2016 PM2.5 Plan relies on three types 

of emission reductions: (1) 0.6 tpd direct 

PM2.5 and 9.7 tpd NOX emission 

reductions that are surplus to those 

needed by 2019 to meet that year’s 

linear RFP target emissions, (2) 0.3 tpd 

NOX emission reductions from the 

January 2015 amendment to Rule 4905 

(‘‘Natural Gas-Fired, Fan-Type Central 

Furnaces’’) as being surplus to those 

captured in the 2016 PM2.5 Plan’s 

emissions inventory, and (3) 3.0 tpd 

NOX of incentive-based emission 

reductions in conjunction with Rule 

9610 (‘‘State Implementation Plan 

Credit for Emission Reductions 

Generated Through Incentive 

Programs’’).203

CARB and the District then 

established a ratio of 1:8.8 to trade 

direct PM2.5 emissions for NOX

emissions based on the 2016 PM2.5

Plan’s precursor sensitivity analysis for 

the traditional high design value sites in 

Bakersfield.204 After accounting for the 

0.4 tpd direct PM2.5 emission reductions 

that would meet the 2019 RFP target 

emission reductions, per the 2019 RFP 

target emission reductions, the 

contingency measure element relies on 

this trading ratio to convert 0.2 tpd of 

additional direct PM2.5 emission 

reductions in 2019 into 1.8 tpd of NOX

emission reductions equivalent (after 

rounding to the tenths place).205 Then, 

after accounting for NOX emission 

reductions that would meet the 2019 

RFP target emissions reductions, the 

contingency measure element sums 9.7 

tpd of surplus NOX emission reductions 

with 0.3 tpd from the 2015 amendment 

to Rule 4905, 1.8 tpd from the surplus 

direct PM2.5 conversion, and 3.0 tpd 

from the incentive-based emission 

reductions. The sum of these four types 

of reductions equals 14.8 tpd NOX, 

which matches the State’s estimate of 

one year’s worth of RFP. 

Therefore, the 2016 PM2.5 Plan 

concludes that these emission 

reductions (equivalent to one year’s 

worth of progress, i.e., 0.4 tpd direct 

PM2.5 and 14.8 tpd NOX) are sufficient 

to satisfy the contingency measure 

requirements for the 2012 PM2.5 NAAQS 

in the SJV. 

b. 2018 PM2.5 Plan Contingency 

Measures 

The 2018 PM2.5 Plan addresses the 

contingency measure requirement for 

the 2012 PM2.5 NAAQS by reference to 

the contingency measure portion of a 

December 2018 SIP submission that 

involved enhanced enforcement of 

CARB regulations in the SJV, a 

commitment to amend the District’s 

residential wood burning rule (District 

Rule 4901) to include contingent 

provisions, and emissions estimates for 

the year following the attainment year 

for use in evaluating whether the 

emissions reductions from the 


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206 2018 PM2.5 Plan, App. H (revised February 11, 

2020), H–24 to H–26. 

207Letter dated March 19, 2021, from Richard W. 

Corey, Executive Officer, CARB, to Deborah Jordan, 

Acting Regional Administrator, EPA Region IX, 

with enclosures. 

208The estimate of one year’s RFP is based on 

difference between the annual average base year 

(2013) emissions and the corresponding emissions 

in the 2022 RFP milestone year, per Appendix B of 

the 2018 PM2.5 Plan, divided by nine (i.e., the 

number of years between 2013 and 2022). 

209Letter from Richard W. Corey, Executive 

Officer, CARB, to Mike Stoker, Regional 

Administrator, EPA Region IX, July 19, 2019. 210 85 FR 44206 (July 22, 2020) (final approval of 

District Rule 4901); 85 FR 1131, 1132–33 (January 

9, 2020) (proposed approval of District Rule 4901). 

contingency measures are sufficient.206

Recently, CARB withdrew the enhanced 

enforcement contingency measure of the 

December 2018 SIP submission as it 

pertained to the 2012 PM2.5 NAAQS in 

the SJV.207 In addition, the 2018 PM2.5

Plan does not include updated 

emissions estimates for the years 

following the 2019 and 2022 RFP 

milestone years with which to evaluate 

the sufficiency of contingency measure 

intended to address the applicable 

Moderate area requirements for the 2012 

PM2.5 NAAQS. Rather, with respect to 

the 2012 PM2.5 NAAQS, the contingency 

measure element of the 2018 PM2.5 Plan 

only includes estimates for the year 

(2026) following the Serious area 

attainment year (2025), and thus, these 

estimates are not relevant for evaluating 

the sufficiency of contingency measures 

submitted to comply with the Moderate 

area requirements for the 2012 PM2.5

NAAQS. 

Accordingly, we have evaluated the 

relevant portions of the 2018 PM2.5 Plan 

and District Rule 4901 (specifically, 

section 5.7.3 of Rule 4901), and the 

contingency measure element in the 

2016 PM2.5 Plan as discussed above, for 

compliance with the applicable 

requirements for Moderate areas for the 

2012 PM2.5 NAAQS. However, while the 

2018 PM2.5 Plan does not provide 

updated emissions estimates for the 

years following the 2019 and 2022 RFP 

milestone years, the updated emission 

estimates in the 2018 PM2.5 Plan do 

provide the basis for an updated 

estimate of one year’s worth of RFP for 

the purposes of evaluating the 

sufficiency of contingency measures to 

meet the applicable Moderate area 

requirements for the 2012 PM2.5

NAAQS. The updated estimates of 

emissions one year’s worth of RFP based 

on the updated emissions estimates in 

the 2018 PM2.5 Plan are 0.5 tpd direct 

PM2.5 and 15.3 tpd NOX.208 This is 

slightly more reductions than the 0.4 

tpd direct PM2.5 and 14.8 tpd NOX

emission reductions estimated as one 

year’s RFP within the 2016 PM2.5 Plan, 

consistent with the slightly faster pace 

of emission reductions reflected in the 

2018 PM2.5 Plan and discussed in 

section IV.G.3 of this proposed rule. 

With respect to the District 

contingency measure, the 2018 PM2.5

Plan calls for the District to amend 

District Rule 4901 (Wood Burning 

Fireplaces and Wood Burning Heaters) 

to include a requirement in the rule 

with a trigger that would be activated 

should the EPA issue a final rulemaking 

that the SJV failed to meet a regulatory 

requirement necessitating 

implementation of a contingency 

measure. In response to the commitment 

made in the 2018 PM2.5 Plan, in June 

2019, the District adopted amendments 

to Rule 4901 including a contingency 

measure (in section 5.7.3 of the 

amended rule), and, as an attachment to 

a letter dated July 19, 2019, CARB 

submitted the amended rule to the EPA 

for approval.209 The EPA has taken final 

action to approve amended Rule 4901, 

but in that approval, we noted that we 

were not evaluating the contingency 

measure in section 5.7.3 of revised Rule 

4901 for compliance with all 

requirements of the CAA and the EPA’s 

implementing regulations that apply to 

such measures.210 Rather, we approved 

the measure into the SIP because it 

strengthened the rule by providing a 

possibility of additional curtailment 

days, and thus potentially additional 

emissions reductions. We indicated that 

we would evaluate whether this 

provision, in conjunction with other 

submitted provisions, meets the 

statutory and regulatory requirements 

for contingency measures in future 

actions. In this proposal, we are now 

evaluating District Rule 4901, 

specifically, section 5.7.3, for 

compliance with the requirements for 

contingency measures for Moderate 

areas that cannot practicably attain the 

2012 PM2.5 NAAQS by the applicable 

Moderate area attainment date. 

District Rule 4901 is designed to limit 

emissions generated by the use of wood 

burning fireplaces, wood burning 

heaters, and outdoor wood burning 

devices. The rule establishes 

requirements for the sale/transfer, 

operation, and installation of wood 

burning devices and for advertising the 

sale of seasoned wood consistent with a 

moisture content limit within the SJV. 

The rule includes a two-tiered, 

episodic wood burning curtailment 

requirement that applies during four 

winter months, November through 

February. During a level one episodic 

wood burning curtailment, section 5.7.1 

prohibits any person from operating a 

wood burning fireplace or unregistered 

wood burning heater but permits the use 

of a properly operated wood burning 

heater that meets certification 

requirements and has a current 

registration with the District. Sections 

5.9 through 5.11 impose specific 

registration requirements on any person 

operating a wood burning fireplace or 

wood burning heater and section 5.12 

imposes specific certification 

requirements on wood burning heater 

professionals. During a level two 

episodic wood burning curtailment, 

operation of any wood burning device is 

prohibited by section 5.7.2. 

Prior to the 2019–2020 wood burning 

season, the District imposed a level one 

curtailment when the PM2.5

concentration was forecasted to be 

between 20–65 mg/m3 and imposed a 

level two curtailment when the PM2.5

concentration was forecasted to be 

above 65 mg/m3 or the PM10

concentration was forecasted to be 

above 135 mg/m3. In 2019 the District 

adopted revisions to Rule 4901 to lower 

the wood burning curtailment 

thresholds in the ‘‘hot spot’’ counties of 

Madera, Fresno, and Kern. The District 

lowered the level one PM2.5 threshold 

for these three counties from 20 mg/m3

to 12 mg/m3, and the level two PM2.5

threshold from 65 mg/m3 to 35 mg/m3. 

The District did not modify the 

curtailment thresholds for other 

counties (i.e., Kings, Merced, San 

Joaquin, Stanislaus, and Tulare 

counties) in the SJV, and those levels 

remained at 20 mg/m3 for level one and 

65 mg/m3 for level two. 

The District’s 2019 revision to Rule 

4901 also included the addition of a 

contingency measure in section 5.7.3 of 

the rule, requiring that 60 days 

following the effective date of an EPA 

final rulemaking that the SJV has failed 

to attain the 1997, 2006, or 2012 PM2.5

NAAQS by the applicable attainment 

date, the PM2.5 curtailment levels for 

any county that has failed to attain the 

applicable standard will be lowered to 

the curtailment levels in place for hot 

spot counties. 

3. EPA Evaluation and Proposed Action 

We have evaluated the contingency 

measure element in the 2016 PM2.5 Plan, 

as amended in the 2018 PM2.5 Plan, and 

we find that the fact that the element 

focuses only on direct PM2.5 and NOX

(and not ammonia, SO2, and VOC) is 

acceptable in light of our proposed 

approval of the precursor demonstration 

in section IV.B of this document. 

PM2.5 attainment plan SIP submission 

for Moderate areas that cannot 

practicably attain by the Moderate area 

attainment date must include 


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211We note that the Ninth Circuit’s decision in 

Bahr v. EPA was published on September 12, 2016, 

just three days before the SJVUAPCD adopted the 

2016 PM2.5 Plan on September 15, 2016. 

Subsequently, the District and CARB addressed the 

Bahr decision within their discussion of 

contingency measures for the Serious area plan for 

the 2012 PM2.5 NAAQS in the San Joaquin Valley 

(i.e., the 2018 PM2.5 Plan). 

212 80 FR 19020 (April 9, 2015) (final approval of 

Rule 9610), 79 FR 28652 (May 19, 2014) (proposed 

approval noting that ‘‘[Rule 9610] does not establish 

any emission limitation, control measure, or other 

requirement that applies directly to an emission 

source’’), and EPA, Region IX Air Division, 

‘‘Technical Support Document for EPA’s Notice of 

Proposed Rulemaking for the California State 

Implementation Plan, San Joaquin Valley Unified 

Air Pollution Control District’s Rule 9610, State 

Implementation Plan Credit for Emission 

Reductions Generated through Incentive Programs,’’ 

May 2014, 4–5 (noting that Rule 9610 ‘‘does not 

apply to any emission source and does not directly 

impact emissions’’). 

213The EPA’s longstanding position with respect 

to incentive-based control measures is that SIP 

credit may be allowed for such measures only 

where the State submits enforceable mechanisms to 

ensure that the emission reductions necessary to 

meet applicable CAA requirements are achieved— 

e.g., an enforceable commitment to monitor and 

report on emission reductions achieved and to 

rectify any shortfall in a timely manner. See, e.g., 

80 FR 19020, 19026. The 2016 PM2.5 Plan does not 

contain such enforceable mechanisms addressing 

the Carl Moyer projects listed in Appendix C. 

214EPA, Region IX Air Division, ‘‘Technical 

Support Document for EPA’s Proposed Rulemaking 

for the California State Implementation Plan (SIP), 

San Joaquin Valley Unified Air Pollution Control 

District’s Rule 4905, Natural Gas-Fired, Fan-Type 

Central Furnaces,’’ October 5, 2015, fn. 8. The EPA 

approved the 2015 amended version of District Rule 

4905 at 81 FR 17390 (March 29, 2016). 

215CARB and the District have prepared and 

submitted the 2019 quantitative milestone report 

and we are currently reviewing it for adequacy. 

contingency measures for potential 

failures to meet RFP, submit a 

quantitative milestone report or meet 

the quantitative milestones associated 

with the period 4.5 and 7.5 years after 

designation (in this case, the 2019 and 

2022 RFP milestone years). With respect 

to both RFP milestone years, we find 

that the contingency measure element is 

inadequate to meet the Moderate area 

contingency measure requirements for 

several reasons. 

First, the emission reductions relied 

upon in the contingency measure 

element to show compliance with the 

contingency measure requirement (i.e., 

those surplus to RFP, reductions from 

the 2015 amendments to Rule 4905, and 

incentive-based emission reductions 

from projects in 2011–2016 in 

conjunction with District Rule 9610) 

come from measures that are not 

prospective (i.e., to-be-triggered) but 

rather come from measures that have 

already been implemented, and thus 

would not constitute contingency 

measures under CAA section 172(c)(9) 

consistent with the Bahr decision.211

We recognize that the District has 

taken action to fulfill the commitment 

in the 2018 PM2.5 Plan to revise District 

Rule 4901 to include specific to-betriggered contingency provisions. 

However, the contingency measure 

provision (section 5.7.3) added to the 

rule is only triggered by a finding of 

failure to attain the PM2.5 NAAQS by the 

applicable attainment date and not by 

failures to meet a quantitative 

milestone, submit a quantitative 

milestone report, or failure to meet an 

RFP requirement. Thus, the rule does 

not include contingency provisions to 

address the types of failures that are the 

triggering events for contingency 

measures for Moderate areas that cannot 

practicably attain the PM2.5 NAAQS by 

the applicable attainment date. 

Therefore, section 5.7.3 of District Rule 

4901 does not meet the contingency 

measure requirements of CAA section 

172(c)(9) and 40 CFR 51.1014 for the 

SJV with respect to Moderate area 

requirements for the 2012 PM2.5

NAAQS. 

Second, as a general matter, we find 

that surplus emissions reductions in the 

years following RFP milestone years can 

be taken into account in determining 

whether a contingency measure or 

contingency measures are adequate for a 

given area for a given pollutant 

notwithstanding the fact that the 

contingency measure or contingency 

measures would not achieve reductions 

equivalent to one year’s worth of RFP. 

However, the contingency measure 

element in the 2016 PM2.5 Plan provides 

no emissions estimates for the year 

following the 2022 RFP milestone year 

for such an evaluation. The contingency 

measure element of the nonattainment 

area plan only provides estimates of 

surplus emissions reductions in 2019. 

Furthermore, with respect to the 

emissions analysis for 2019, neither 

Rule 9610 (‘‘State Implementation Plan 

Credit for Emission Reductions 

Generated Through Incentive 

Programs’’) nor the list of Carl Moyer 

incentive projects in Appendix C of the 

2016 PM2.5 Plan may be relied upon as 

a source for surplus emissions 

reductions because Rule 9610 is not an 

emission reduction measure 212 and 

because the Carl Moyer incentive 

projects listed in Appendix C of the 

2016 PM2.5 Plan do not satisfy CAA 

requirements for SIP emission reduction 

credit, as interpreted in the EPA’s 

guidance.213 In addition, the emission 

reductions that might otherwise be 

considered surplus due to the 2015 

adoption of tighter emissions limits in 

District Rule 4905 would not be 

considered surplus without additional 

documentation because of the option in 

Rule 4905 to pay mitigation fees in lieu 

of compliance with emissions limits.214

Third, as a general matter, we agree 

that the use of trading ratios established 

through modeling techniques to convert 

surplus reductions of direct PM2.5

emissions to equivalent PM2.5 precursor 

emissions may be appropriate as part of 

the explanation for why a given 

contingency measure or measures are 

sufficient in an area with respect to a 

specific NAAQS. In this instance, 

however, we note that reliance on 

trading surplus direct PM2.5 reductions 

for NOX reductions at a ratio of 1:8.8 

may overestimate the amount of 

equivalent NOX reductions based on the 

information in the 2018 PM2.5 Plan. For 

the 2018 PM2.5 Plan, the State 

conducted further analysis of the 

sensitivity of ambient PM2.5 to emission 

reductions in PM2.5 precursors, as 

discussed in section IV.I.2 of this 

proposal. Based on this updated 

analysis for Bakersfield and Fresno 

sites, the State proposes to use a 1:6.5 

trading ratio between direct PM2.5 and 

NOX for purposes of the 2018 PM2.5

Plan’s MVEBs. This suggests that, while 

for a different CAA purpose (i.e., MVEB 

rather than contingency measures), any 

excess direct PM2.5 used for evaluation 

of contingency measures would be 

equivalent to fewer NOX emissions 

reductions than assumed for the 2016 

PM2.5 Plan. 

Therefore, in light of the deficiencies 

described in the preceding paragraphs, 

we are proposing to disapprove the 

contingency measure element of the 

2016 PM2.5 Plan, as amended in the 

2018 PM2.5 Plan, for failure to meet the 

requirements for contingency measures 

under CAA section 172(c)(9) and 40 

CFR 51.1014(a) in the SJV with respect 

to Moderate area requirements for the 

2012 PM2.5 NAAQS. More specifically, 

we are proposing to disapprove the 

contingency measure element for failure 

to provide for the implementation of 

specific measures to be undertaken if 

the area fails, with respect to the 2019 

and 2022 RFP milestone years, to meet 

RFP, to submit a quantitative milestone 

report (2022 RFP milestone year 

only),215 or to meet the quantitative 

milestones and that, once triggered, 

provide sufficient emissions reductions 

to meet the purposes of contingency 

measures under the CAA and EPA’s 

implementing regulations. 

I. Motor Vehicle Emissions Budgets 

1. Requirements for Motor Vehicle 

Emissions Budgets 

Section 176(c) of the CAA requires 

federal actions in nonattainment and 


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216 40 CFR 93.118(e)(4)(v). 217 40 CFR 51.1013(a)(1). 218Because the SJV was designated 

nonattainment effective April 15, 2015, the first 

milestone date is October 15, 2019, and the second 

milestone date is October 15, 2022. 80 FR 2206. 

219 81 FR 58010, 58058 and 58063–58064. 

220 Id. at 58055. 

221 40 CFR 93.102(b)(3), 93.102(b)(2)(v), and 

93.122(f); see also transportation conformity rule 

preambles at 69 FR 40004, 40031–40036 (July 1, 

2004), 70 FR 24280, 24283–24285 (May 6, 2005) 

and 70 FR 31354 (June 1, 2005). 

222 70 FR 24280, 24287 (May 6, 2005). 

223 40 CFR 93.102(b)(2)(iv). 

224 69 FR 40004. 

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, 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 MVEBs contained in all control 

strategy SIPs. An attainment, 

maintenance, or RFP SIP should include 

budgets for the attainment year, each 

required RFP milestone year, and the 

last year of the maintenance plan, as 

appropriate. Budgets are generally 

established for specific years and 

specific pollutants or precursors and 

must reflect all of the motor vehicle 

control measures contained in the 

attainment and RFP demonstrations.216

Under the PM2.5 SIP Requirements 

Rule, each attainment plan submittal for 

a Moderate PM2.5 nonattainment area 

must contain quantitative milestones to 

be achieved no later than 4.5 years and 

7.5 years after the date the area was 

designated nonattainment.217 The 

second of these milestone dates, October 

15, 2022,218 falls after the latest 

permissible Moderate area attainment 

date for the SJV, which is December 31, 

2021. As the EPA explained in the 

preamble to the PM2.5 SIP Requirements 

Rule, it is important to include a postattainment year quantitative milestone 

to ensure that, if the area fails to attain 

by the attainment date, the EPA can 

continue to monitor the area’s progress 

toward attainment while the state 

develops a new attainment plan.219

Moderate area plans demonstrating that 

attainment by the Moderate area 

attainment date is impracticable must, 

therefore, include budgets for both of 

the milestone dates. States that submit 

impracticability demonstrations for 

Moderate areas under CAA section 

189(a)(1)(B)(ii), however, are not 

required to submit budgets for the 

attainment year because the submitted 

SIP does not demonstrate attainment.220

PM2.5 plans should identify budgets 

for direct PM2.5, NOX, and all other 

PM2.5 precursors for which on-road 

emissions are determined to contribute 

significantly to PM2.5 levels in the area 

for each RFP milestone year and the 

attainment year, if the plan 

demonstrates attainment. All direct 

PM2.5 SIP budgets should include direct 

PM2.5 motor vehicle emissions from 

tailpipes, brake wear, and tire wear. 

With respect to PM2.5 from re-entrained 

road dust and emissions of VOC, SO2, 

and/or ammonia, the transportation 

conformity provisions of 40 CFR part 

93, subpart A, apply only if the EPA 

Regional Administrator or the director 

of the state air agency has made a 

finding that transportation-related 

emissions of these pollutants within the 

area are a significant contributor to the 

PM2.5 nonattainment problem and has 

so notified the MPO and Department of 

Transportation (DOT), or if the 

applicable implementation plan (or 

implementation plan submission) 

includes any of these pollutants in the 

approved (or adequate) budget as part of 

the RFP, attainment, or maintenance 

strategy.221 Additionally, as the EPA 

explained in its May 6, 2005 

transportation conformity rule 

amendments for the PM2.5 NAAQS, it is 

not necessary for a SIP to explicitly state 

that VOC, SO2, and/or ammonia are 

insignificant precursors. Instead, states 

should consider the on-road 

contribution of all four precursors to the 

PM2.5 problem as they develop their 

SIPs and establish emissions budgets for 

those precursors for which on-road 

emissions need to be addressed in order 

to attain the PM2.5 standard as 

expeditiously as practicable. Conformity 

determinations must address all 

precursors for which the SIP establishes 

a budget and need not address those 

precursors for which the state has not 

established a budget because the 

emissions of that precursor are 

insignificant.222

By contrast, transportation conformity 

requirements apply with respect to 

emissions of NOX unless both the EPA 

Regional Administrator and the director 

of the state air agency have made a 

finding that transportation-related 

emissions of NOX within the 

nonattainment area are not a significant 

contributor to the PM2.5 nonattainment 

problem and have so notified the MPO 

and DOT, or the applicable 

implementation plan (or 

implementation plan submission) does 

not establish an approved (or adequate) 

budget for such emissions as part of the 

RFP, attainment, or maintenance 

strategy.223

The criteria for insignificance 

determinations are provided in 40 CFR 

93.109(f). In order for a pollutant or 

precursor to be considered an 

insignificant contributor, the control 

strategy SIP must demonstrate that it 

would be unreasonable to expect that 

such an area would experience enough 

motor vehicle emissions growth in that 

pollutant/precursor for a NAAQS 

violation to occur. Insignificance 

determinations are based on factors 

such as air quality, SIP motor vehicle 

control measures, trends and projections 

of motor vehicle emissions, and the 

percentage of the total SIP inventory 

that is comprised of motor vehicle 

emissions. The EPA’s rationale for 

providing for insignificance 

determinations is described in the July 

1, 2004, revision to the transportation 

conformity rule.224

The EPA’s process for determining the 

adequacy of a budget consists of three 

basic steps: (1) Notifying the public of 

a SIP submittal; (2) providing the public 

the opportunity to comment on the 

budget during a public comment period; 

and (3) making a finding of adequacy or 

inadequacy. The EPA can notify the 

public by either posting an 

announcement that the EPA has 

received SIP budgets on the EPA’s 

adequacy website (40 CFR 93.118(f)(1)), 

or through a Federal Register notice of 

proposed rulemaking when the EPA 

reviews the adequacy of an 

implementation plan budget 

simultaneously with its review and 

action on the SIP itself (40 CFR 

93.118(f)(2)). 

For budgets to be approvable, they 

must meet, at a minimum, the EPA’s 

adequacy criteria (40 CFR 93.118(e)(4)). 

To meet these requirements, the budgets 

must be consistent with the attainment 

and RFP requirements and reflect all of 

the motor vehicle control measures 


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225 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. 

226 2016 PM2.5 Plan, Table 3–11. 

227 2018 PM2.5 Plan, App. D, Table 3–3. 

228 2018 PM2.5 Plan, App. D, D–121 to D–123. 

229 76 FR 69896, at 69923 (November 9, 2011). 

230 2018 PM2.5 Plan, App. D, D–126 and D–127. 

231Letter dated May 9, 2019, from Richard W. 

Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX, 3. 

232The differences between the two sets of 

budgets are minor. For 2019, there is no difference 

between the budgets in the 2016 PM2.5 Plan and the 

2018 PM2.5 Plan. For 2022, there is no difference 

between the two sets of budgets for direct PM2.5, 

and, with the exception of San Joaquin County, the 

difference between the two sets of budgets for NOX

is less than or equal to 0.1 tpd. For San Joaquin 

County, the 2022 NOX budget is 0.7 tpd higher 

under the 2018 PM2.5 Plan than the corresponding 

budget from the 2016 PM2.5 Plan. 

contained in the attainment and RFP 

demonstrations.225

2. Summary of State’s Motor Vehicle 

Emissions Budgets 

The 2016 PM2.5 Plan includes budgets 

for direct PM2.5 and NOX for 2019 (RFP 

milestone year) and 2022 (postattainment RFP milestone year) and no 

other year given the plan’s 

demonstration of the impracticability of 

attaining the 2012 PM2.5 NAAQS by 

2021.226 Similarly, for the Moderate area 

timeframe, the 2018 PM2.5 Plan includes 

budgets for direct PM2.5 and NOX for 

2019 and 2022 RFP milestone years.227

We consider the 2019 and 2022 RFP 

milestone budgets from the 2018 PM2.5

Plan as superseding the corresponding 

budgets from the 2016 PM2.5 Plan. 

The budgets in both the 2016 PM2.5

Plan and the 2018 PM2.5 Plan were 

calculated using EMFAC2014 and the 

latest modeled vehicle activity data 

(vehicle miles traveled and speed 

distributions) available at the time of 

plan development. In the case of the 

2016 PM2.5 Plan, vehicle activity data 

are derived from the draft 2017 FederalStatewide Transportation Improvement 

Program (2017 FSTIP) from each of the 

SJV’s eight MPOs. The 2018 PM2.5 Plan 

budgets are based on updated motor 

vehicle activity data from the most 

recently amended 2017 FSTIP (as of 

January 2018) from each of the SJV’s 

eight MPOs. The budgets reflect annual 

average emissions consistent with the 

annual averaging period of the 2012 

PM2.5 NAAQS and the 2018 PM2.5 Plan’s 

RFP demonstration. 

As with the 2016 PM2.5 Plan, the 2018 

PM2.5 Plan includes direct PM2.5 budgets 

for tailpipe, brake wear, and tire wear 

emissions, but does not include paved 

road dust, unpaved road dust, and road 

construction dust emissions. The 2018 

PM2.5 Plan also includes budgets for 

NOX, as a regulated precursor under the 

plan, but does not include budgets for 

VOC, SO2, or ammonia.228 The budgets 

included in the 2018 PM2.5 Plan with 

respect to the Moderate area timeframe 

are shown in Table 6. 

TABLE 6—2019 AND 2022 SAN JOAQUIN VALLEY MVEBS FOR THE 2012 PM2.5 NAAQS 

[Annual average, tpd] 

County 

2019 (RFP year) 2022 (post-attainment year) 

PM2.5 NOX PM2.5 NOX

Fresno .............................................................................................................. 0.9 27.6 0.9 21.2 

Kern (San Joaquin Valley portion) .................................................................. 0.8 25.1 0.8 19.4 

Kings ................................................................................................................ 0.2 5.1 0.2 4.1 

Madera ............................................................................................................. 0.2 4.6 0.2 3.5 

Merced ............................................................................................................. 0.3 9.4 0.3 7.6 

San Joaquin ..................................................................................................... 0.6 12.7 0.6 10.0 

Stanislaus ........................................................................................................ 0.4 10.5 0.4 8.1 

Tulare ............................................................................................................... 0.4 9.3 0.4 6.9 

Source: 2018 PM2.5 Plan, App. D, Table 3–3. Budgets are rounded up to the nearest tenth. 

The 2018 PM2.5 Plan also includes a 

proposed trading mechanism for 

transportation conformity analyses that 

would allow future decreases in NOX

emissions from on-road mobile sources 

to offset any on-road increases in direct 

PM2.5 emissions. For the 2012 PM2.5

NAAQS, the State is proposing to use 

the 6.5:1 NOX:PM2.5 ratio. The ratio is 

based on a sensitivity analysis based on 

a 30% reduction of NOX or PM2.5

emissions and the corresponding impact 

on design values at sites in Bakersfield 

and Fresno (i.e., updated analysis 

relative to the 2008 PM2.5 Plan for the 

1997 PM2.5 NAAQS). For the sake of 

comparison, in approving the budgets 

for the SJV 2008 PM2.5 Plan for the 1997 

PM2.5 NAAQS, the EPA approved a 

trading mechanism for transportation 

conformity analyses that allowed for 

such one-way trades (i.e., only excess 

NOX can be used to offset PM2.5, not 

vice versa) at a 9:1 NOX:PM2.5 ratio.229

To ensure that the trading mechanism 

does not affect the ability of the SJV to 

meet the NOX budget, the NOX emission 

reductions available to supplement the 

PM2.5 budget would only be those 

remaining after the NOX budget has 

been met.230 The Plan also provides that 

the SJV MPOs shall clearly document 

the calculations used in the trading, 

along with any additional reductions of 

NOX and PM2.5 emissions in the 

conformity analysis. 

In the submittal letter for the 2018 

PM2.5 Plan, CARB requested that we 

limit the duration of our approval of the 

budgets to the period before the 

effective date of the EPA’s adequacy 

finding for any subsequently submitted 

budgets.231

3. EPA Evaluation and Proposed Action 

For the reasons discussed in section 

IV.F of this proposed rule, we are 

proposing to approve the State’s 

demonstration that it is impracticable to 

attain the 2012 PM2.5 standard in the 

SJV by the applicable Moderate area 

attainment date of December 31, 2021, 

and are proposing to reclassify the area 

as Serious. Accordingly, we are 

proposing action on the Moderate postattainment year budgets for 2022 for the 

2012 PM2.5 NAAQS in the SJV. The EPA 

is not reviewing the submitted motor 

vehicle emissions budgets for 2019 

because that year will not be an 

applicable conformity analysis year in 

the next conformity analysis for the SJV 

MPOs. Also, as noted above, we 

consider the 2022 RFP milestone 

budgets from the 2018 PM2.5 Plan as 

superseding the corresponding budgets 

from the 2016 PM2.5 Plan and thus are 

proposing action only on the former.232

The EPA generally first conducts a 

preliminary review of budgets 

submitted with an attainment or 

maintenance plan for PM2.5 for 


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233 2018 PM2.5 Plan, App. D. pages D–121, D–122 

and D–123. Motor vehicle emissions of VOC 

represent approximately 10% of the total VOC 

emissions in the SJV, but VOC controls are 

generally ineffective at reducing ambient PM2.5

levels. Motor vehicle emissions of SO2 are less than 

one tpd, and motor vehicle emissions of ammonia 

represent approximately 1% of total ammonia 

emissions in the SJV. 

234 Id. Paved and unpaved road dust emissions 

represent less than 17% of the total PM2.5 emissions 

in the SJV but contribute only approximately 4% 

to the design values. Construction dust emissions 

are less than 5% of the total PM2.5 emissions in the 

SJV. In addition, the 2018 PM2.5 Plan does not 

include additional control measures for these 

sources. 

235Memorandum of July 30, 2021, from Rory 

Mays and Karina O’Connor, Air Planning Office, 

Air and Radiation Division, Region IX, EPA, ‘‘EPA 

Review of 2018 PM2.5 Plan Transportation 

Conformity Emission Budgets for the 2012 Annual 

PM2.5 NAAQS (Moderate Area Requirements).’’ 

236 80 FR 1816, 1841 (January 13, 2015) (noting 

the EPA’s prior approval of MVEBs for the 1997 

annual and 24-hour PM2.5 standards in the 2008 

PM2.5 Plan at 76 FR 69896). 237 81 FR 59876 (August 31, 2016). 238 2018 PM2.5 Plan, App. D, D–126. 

adequacy, prior to taking action on the 

plan itself, and did so with respect to 

the PM2.5 budgets in the 2018 PM2.5

Plan. On June 18, 2019, the EPA 

announced the availability of the 2018 

PM2.5 Plan with MVEBs and a 30-day 

public comment period. This 

announcement was posted on the EPA’s 

adequacy website at: https://

www.epa.gov/state-and-localtransportation/state-implementationplans-sip-submissions-currently-underepa. The comment period for this 

notification ended on July 18, 2019. We 

did not receive any comments during 

this comment period. 

The 2018 PM2.5 Plan establishes 

budgets for the 2022 RFP milestone year 

for direct PM2.5 and NOX, but not for the 

other PM2.5 precursor emissions (i.e., 

VOC, SO2, and ammonia). We propose 

to find that it is not necessary to 

establish motor vehicle emissions 

budgets for transportation-related 

emissions of VOC, SO2, and ammonia to 

attain the 2012 annual PM2.5 NAAQS in 

the SJV based on our proposal to 

approve the State’s demonstration that 

emissions of VOC, SO2, and ammonia 

do not contribute significantly to PM2.5

levels that exceed the 2012 PM2.5

NAAQS in the SJV, as discussed in 

section IV.B of this proposed rule. Our 

finding in this regard is also supported 

by information about VOC, SO2, and 

ammonia in the 2018 PM2.5 Plan 

documenting the small contribution by 

motor vehicles to regional precursor 

inventories and to PM2.5 design values 

within the SJV.233 In addition, based on 

similar documentation about reentrained road dust and constructionrelated fugitive dust in the 2018 PM2.5

Plan and in accordance with 40 CFR 

93.102(b)(3) and 93.122(f), the EPA 

proposes to find that it is not necessary 

to include re-entrained road dust 

emissions or road construction dust in 

the direct PM2.5 budgets for 2012 PM2.5

NAAQS in the SJV.234

For the reasons discussed in sections 

IV.G of this proposed rule, the EPA 

proposes to approve the RFP 

demonstration in the 2018 PM2.5 Plan. 

The 2022 RFP budgets, as shown in 

Table 6 of this proposed rule, are 

consistent with this demonstration, are 

clearly identified and precisely 

quantified, and meet all other applicable 

statutory and regulatory requirements 

including the adequacy criteria in 40 

CFR 93.118(e)(4) and (5). For these 

reasons, the EPA proposes to approve 

the budgets listed in Table 6. We 

provide a more detailed discussion in 

the EPA’s memo to file regarding 

MVEB.235 We are not proposing to 

approve the 2018 PM2.5 Plan’s budgets 

that pertain solely to the Serious area 

time frame (i.e., 2025 attainment year 

budget or the post-attainment year 2028 

budget for the 2012 PM2.5 NAAQS) at 

this time. The budgets that the EPA is 

proposing to approve relate to the 2012 

annual PM2.5 NAAQS only, and our 

proposed approval does not affect the 

status of the previously-approved 

MVEBs for the 1997 annual and 24-hour 

PM2.5 NAAQS and 2006 24-hour PM2.5

NAAQS and related trading 

mechanisms that remain in effect for 

that PM2.5 NAAQS. 

As noted above, the State included a 

trading mechanism to be used in 

transportation conformity analyses that 

would be used in conjunction with the 

budgets in the 2018 PM2.5 Plan, as 

allowed for under 40 CFR 93.124(b). 

Furthermore, the trading ratio in the 

2018 PM2.5 Plan is based on updated air 

quality modeling and analysis relative 

to the analysis that the 2016 PM2.5 Plan 

relies on (i.e., analysis and trading ratio 

in the 2008 PM2.5 Plan for the 1997 

PM2.5 NAAQS). The trading mechanism 

in the 2018 PM2.5 Plan would allow 

future decreases in annual NOX

emissions from on-road mobile sources 

to offset any on-road increases in annual 

direct PM2.5 emissions using a 6.5:1 

NOX:PM2.5 ratio for conformity for the 

2012 annual PM2.5 NAAQS. To ensure 

that the trading mechanism does not 

affect the ability to meet the NOX

budget, the plan provides that the NOX

emission reductions available to 

supplement the PM2.5 budget would 

only be those remaining after the NOX

budget has been met. The SJV MPOs 

will have to document clearly the 

calculations used in the trading when 

demonstrating conformity, along with 

any additional reductions of NOX and 

PM2.5 emissions in the conformity 

analysis. The trading calculations must 

be performed prior to the final rounding 

to demonstrate conformity with the 

budgets. 

The EPA has reviewed the trading 

mechanism as described on pages D– 

125 through D–127 in Appendix D of 

the 2018 PM2.5 Plan and finds it is 

appropriate for transportation 

conformity purposes in the SJV for the 

2012 annual PM2.5 NAAQS. The 

methodology for estimating the trading 

ratio for conformity purposes is 

essentially an update (based on newer 

modeling) of the approach that the EPA 

previously approved for the 2008 PM2.5

Plan for the 1997 PM2.5 NAAQS 236 and 

the 2012 PM2.5 Plan for the 2006 24- 

hour PM2.5 NAAQS.237 The State’s 

approach in the previous plans was to 

model the ambient PM2.5 effect of 

areawide NOX emissions reductions and 

of areawide direct PM2.5 reductions, and 

to express the ratio of these modeled 

sensitivities as an interpollutant trading 

ratio. 

In the updated analysis for the 2018 

PM2.5 Plan, the State completed separate 

sensitivity analyses for the annual and 

24-hour standards and modeled only 

transportation-related sources in the 

nonattainment area. The ratio the State 

is proposing to use for transportation 

conformity purposes is derived from air 

quality modeling that evaluated the 

effect of reductions in transportationrelated NOX and PM2.5 emissions in the 

SJV on ambient concentrations at the 

Bakersfield-California Avenue, 

Bakersfield-Planz, Fresno-Garland, and 

Fresno-Hamilton & Winery monitoring 

sites. The modeling that the State 

performed to evaluate the effectiveness 

of NOX and PM2.5 reductions on ambient 

24-hour concentrations showed 

NOX:PM2.5 ratios that range from a high 

of 7.1 at the Bakersfield-California 

Avenue monitor to a low of 6.0 at the 

two Fresno monitors.238 We find that 

the State’s approach is a reasonable 

method to use to develop ratios for 

transportation conformity purposes. We 

therefore propose to approve the 6.5:1 

NOX for PM2.5 trading mechanism as 

enforceable components of the 

transportation conformity program for 

the SJV for the 2012 annual PM2.5

NAAQS. 

Under the transportation conformity 

rule, once budgets are approved, they 

cannot be superseded by revised 

budgets submitted for the same CAA 

purpose and the same year(s) addressed 

by the previously approved SIP until the 

EPA approves the revised budgets as a 


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239 40 CFR 93.118(e)(1). 

240Letter dated May 9, 2019, from Richard W. 

Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX, 3. 

241 40 CFR 93.118(e)(1). 

242 67 FR 69141 (November 15, 2002), limiting 

our prior approval of MVEBs in certain California 

SIPs. 

243On August 15, 2019, the EPA approved and 

announced the availability of EMFAC2017, the 

latest update to the EMFAC model for use by the 

State and local governments to meet CAA 

requirements. 84 FR 41717. 

244Under 40 CFR 93.118(e)(4), the EPA will not 

find a budget in a submitted SIP to be adequate 

unless, among other criteria, the budgets, when 

considered together with all other emissions 

sources, are consistent with applicable 

requirements for RFP and attainment. 40 CFR 

93.118(e)(4)(iv). 

245 40 CFR 93.120(a)(3). 

246For a general discussion of the EPA’s 

interpretation of the reclassification provisions in 

section 188(b)(1) of the Act, see the General 

Preamble, 13537–13538. 

247EPA design value workbook dated May 24, 

2021, ‘‘pm25_designvalues_2018_2020_final_05_

24_21.xlsx,’’ worksheets ‘‘Table1a’’ and ‘‘Table5a,’’ 

and EPA, 2010–2020 AQS Design Value Report, 

AMP480, June 30, 2021. 

248 80 FR 2206. 

SIP revision. As a general matter, such 

approved budgets cannot be superseded 

by revised budgets found adequate, but 

rather only through approval of the 

revised budgets, unless the EPA 

specifies otherwise in its approval of a 

SIP by limiting the duration of the 

approval to last only until subsequently 

submitted budgets are found 

adequate.239

In the submittal letter for the 2018 

PM2.5 Plan, CARB requested that we 

limit the duration of our approval of the 

budgets to the period before the 

effective date of the EPA’s adequacy 

finding for any subsequently submitted 

budgets.240 The transportation 

conformity rule allows us to limit the 

approval of budgets.241 However, we 

will consider a state’s request to limit an 

approval of its MVEBs only if the 

request includes the following 

elements: 242 (1) An acknowledgement 

and explanation as to why the budgets 

under consideration have become 

outdated or deficient; (2) a commitment 

to update the budgets as part of a 

comprehensive SIP update; and (3) a 

request that the EPA limit the duration 

of its approval to the period before new 

budgets have been found to be adequate 

for transportation conformity purposes. 

CARB’s request includes an 

explanation for why the budgets have 

become, or will become, outdated or 

deficient. In short, CARB has requested 

that we limit the duration of the 

approval of the budgets in light of the 

EPA’s approval of EMFAC2017, an 

updated version of the EMFAC2014 

used for the budgets in the 2018 PM2.5

Plan.243 EMFAC2017 updates vehicle 

mix and emissions data of the 

previously approved version of the 

EMFAC2014. 

In light of the EPA’s approval of 

EMFAC2017, CARB explains that the 

budgets in the 2018 PM2.5 Plan, which 

we are proposing to approve in this 

action, will become outdated and will 

need to be revised using EMFAC2017. 

In addition, CARB states that, without 

the ability to replace the budgets using 

the budget adequacy process, the 

benefits of using the updated data may 

not be realized for a year or more after 

the updated SIP (with the EMFAC2017- 

derived budgets) is submitted, due to 

the length of the SIP approval process. 

We find that CARB’s explanation for 

limiting the duration of the approval of 

the budgets is appropriate and provides 

us with a reasonable basis for limiting 

the duration of the approval of the 

budgets. 

We note that CARB has not 

committed to update the budgets as part 

of a comprehensive SIP update, but as 

a practical matter, CARB must submit a 

SIP revision that includes updated 

demonstrations as well as the updated 

budgets to meet the adequacy criteria in 

40 CFR 93.118(e)(4).244 Therefore, we do 

not need a specific commitment for 

such a plan at this time. For the reasons 

provided above, and in light of CARB’s 

explanation for why the budgets will 

become outdated and should be 

replaced upon an adequacy finding for 

updated budgets, we propose to limit 

the duration of our approval of the 

budgets in the 2018 PM2.5 Plan to the 

period before we find revised budgets 

based on EMFAC2017 to be adequate. 

Lastly, in section IV.H of this 

proposed rule, the EPA is proposing to 

disapprove the contingency measure 

element of the 2016 PM2.5 Plan, as 

amended in the 2018 PM2.5 Plan, with 

respect to Moderate area requirements 

for the 2012 PM2.5 NAAQS. If the EPA 

were to finalize the proposed 

disapproval of the 2012 PM2.5 NAAQS 

Moderate area contingency measure 

element, the area would be eligible for 

a protective finding under the 

transportation conformity rule because 

the 2016 PM2.5 Plan and 2018 PM2.5

Plan reflect adopted control measures 

that fully satisfy the emissions 

reductions requirements for RFP for 

years 2019 and 2022.245

V. Reclassification as Serious 

Nonattainment and Serious Area SIP 

Requirements 

A. Reclassification as Serious and 

Applicable Attainment Date 

Section 188 of the Act outlines the 

process for classification of PM2.5

nonattainment areas and establishes the 

applicable attainment dates. Under 

section 188(b)(1) of the Act, the EPA has 

general authority to reclassify at any 

time before the applicable attainment 

date any area that the EPA determines 

cannot practicably attain the standard 

by such date. Accordingly, section 

188(b)(1) of the Act is a general 

expression of delegated rulemaking 

authority. In addition, subparagraphs 

(A) and (B) of section 188(b)(1) mandate 

that the EPA reclassify ‘‘appropriate’’ 

PM10 nonattainment areas at specified 

time frames (i.e., by December 31, 1991, 

for the initial PM10 nonattainment areas, 

and within 18 months after the SIP 

submittal due date for subsequent 

nonattainment areas). These 

subparagraphs do not restrict the EPA’s 

general authority but simply specify 

that, at a minimum, it must be exercised 

at certain times.246

We have reviewed the air quality 

modeling and impracticability 

demonstration in the 2016 PM2.5 Plan, 

as well as the air quality modeling in the 

2018 PM2.5 Plan. Based on our review, 

we agree with the District’s conclusion 

that implementation of the State/ 

District’s SIP control strategy, including 

RACM/RACT and additional reasonable 

measures, is insufficient to bring the SJV 

into attainment of the 2012 PM2.5

NAAQS by the December 31, 2021 

Moderate area attainment deadline. See 

sections IV.C and IV.F of this proposed 

rule. In addition, we have reviewed 

recent PM2.5 monitoring data for SJV 

available in the EPA’s Air Quality 

System (AQS) database. These data 

show that annual PM2.5 levels in the SJV 

continue to be above 12.0 mg/m3, the 

numerical level of the 2012 PM2.5

standard, and the recent trends in the 

SJV annual PM2.5 levels indicate that the 

SJV will not attain by the end of 

2021.247

In accordance with section 188(b)(1) 

of the Act, the EPA is proposing to 

reclassify the SJV from Moderate to 

Serious nonattainment for the 2012 

annual PM2.5 standard of 12.0 mg/m3, 

based on the EPA’s determination that 

the SJV cannot practicably attain the 

standard by the applicable attainment 

date of December 31, 2021. 

Under section 188(c)(2) of the Act, the 

attainment date for a Serious area ‘‘shall 

be as expeditiously as practicable but no 

later than the end of the tenth calendar 

year beginning after the area’s 

designation as nonattainment . . .’’ The 

EPA designated the SJV as 

nonattainment for the 2012 PM2.5

NAAQS effective April 15, 2015.248

Therefore, upon final reclassification of 


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249For a discussion of the EPA’s interpretation of 

the requirements of section 188(e), see General 

Preamble Addendum, 42002; 65 FR 19964 (April 

13, 2000) (proposed action on PM10 Plan for 

Maricopa County, Arizona); 67 FR 48718 (July 25, 

2002) (final action on PM10 Plan for Maricopa 

County, Arizona); and Vigil v. EPA, 366 F.3d 1025, 

amended at 381 F.3d 826 (9th Cir. 2004) (remanding 

EPA action on PM10 Plan for Maricopa County, 

Arizona but generally upholding the EPA’s 

interpretation of CAA section 188(e)). 

250The EPA defines BACM as, among other 

things, the maximum degree of emission reduction 

achievable for a source or source category, which 

is determined on a case-by-case basis considering 

energy, environmental, and economic impacts. 

(General Preamble Addendum, 42010 and 42014). 

BACM must be implemented for all categories of 

sources in a Serious PM2.5 nonattainment area 

unless the State adequately demonstrates that a 

particular source category does not contribute 

significantly to nonattainment of the PM2.5

standard. (Id. at 42011, 42012). 

251For any Serious area, the terms ‘‘major source’’ 

and ‘‘major stationary source’’ include any 

stationary source that emits or has the potential to 

emit at least 70 tpy of PM10 (CAA sections 

189(b)(3)). 

252 40 CFR 93.153(b), 81 FR 58010, 58126. 

253 80 FR 18528 and 81 FR 1514, respectively. 

the SJV as a Serious nonattainment area, 

the latest permissible attainment date 

under section 188(c)(2) of the Act, for 

purposes of the 2012 PM2.5 NAAQS in 

this area, will be December 31, 2025. 

Under section 188(e) of the Act, a 

state may apply to the EPA for a single 

extension of the Serious area attainment 

date of up to five additional years, 

which the EPA may grant if the state 

satisfies certain statutory conditions. 

Before the EPA may extend the 

attainment date for a Serious area under 

section 188(e), the state must: (1) Apply 

for an extension of the attainment date 

beyond the statutory attainment date; (2) 

demonstrate that attainment by the 

statutory attainment date is 

impracticable; (3) demonstrate that it 

has complied with all requirements and 

commitments pertaining to the area in 

the implementation plan; (4) 

demonstrate to the satisfaction of the 

Administrator that the plan for the area 

includes the most stringent measures 

that are included in the implementation 

plan of any state or are achieved in 

practice in any state, and can feasibly be 

implemented in the area; and (5) submit 

a demonstration of attainment by the 

most expeditious alternative date 

practicable.249

B. Clean Air Act Requirements for 

Serious Area Plans 

Upon reclassification as a Serious 

nonattainment area for the 2012 PM2.5

NAAQS, California will be required to 

submit additional SIP revisions to 

satisfy the statutory requirements that 

apply to Serious PM2.5 nonattainment 

areas, including the requirements of 

subpart 4 of part D, title I of the Act. 

The Serious area SIP elements that 

California will be required to submit are 

as follows: 

1. Provisions to assure that BACM,250

including BACT for stationary sources, 

for the control of direct PM2.5 and PM2.5

precursors shall be implemented no 

later than four years after the area is 

reclassified (CAA section 189(b)(1)(B)); 

2. a demonstration (including air 

quality modeling) that the plan provides 

for attainment as expeditiously as 

practicable but not later than December 

31, 2025, or where the state is seeking 

an extension of the attainment date 

under section 188(e), a demonstration 

that attainment by December 31, 2025, 

is impracticable and that the plan 

provides for attainment by the most 

expeditious alternative date practicable 

and not later than December 31, 2030 

(CAA sections 189(b)(1)(A), 188(c)(2), 

and 188(e)); 

3. plan provisions that require RFP 

(CAA section 172(c)(2)); 

4. quantitative milestones that are to 

be achieved every three years until the 

area is redesignated to attainment and 

that demonstrate RFP toward attainment 

by the applicable date (CAA section 

189(c)); 

5. provisions to assure that control 

requirements applicable to major 

stationary sources of PM2.5 also apply to 

major stationary sources of PM2.5

precursors, except where the state 

demonstrates to the EPA’s satisfaction 

that such sources do not contribute 

significantly to PM2.5 levels that exceed 

the standard in the area (CAA section 

189(e)); 

6. a comprehensive, accurate, current 

inventory of actual emissions from all 

sources of PM2.5 and PM2.5 precursors in 

the area (CAA section 172(c)(3)); 

7. contingency measures to be 

implemented if the area fails to meet 

RFP (including quantitative milestones 

and related reports) or to attain by the 

applicable attainment date (CAA section 

172(c)(9)); and 

8. a revision to the NNSR program to 

lower the applicable ‘‘major stationary 

source’’ 251 thresholds from 100 tpy to 

70 tpy (CAA section 189(b)(3)) and to 

satisfy the subpart 4 control 

requirements for major stationary 

sources of PM2.5 precursors (CAA 

section 189(e)). 

As discussed in section IV.E of this 

proposed rule, California submitted 

NNSR SIP revisions for the SJV to 

address the subpart 4 NNSR 

requirements for Serious PM2.5

nonattainment areas on November 20, 

2019. The EPA is evaluating this SIP 

submission and will act on it in a 

separate rulemaking. 

Finally, reclassification of the SJV as 

Serious nonattainment for the 2012 

annual PM2.5 NAAQS would lower the 

de minimis threshold under the CAA’s 

general conformity requirements (40 

CFR part 93, subpart B) from 100 tpy to 

70 tpy for PM2.5 and PM2.5

precursors.252 In this case, however, 

reclassification would have no impact 

on the applicable general conformity de 

minimis thresholds, because the SJV is 

already subject to the 70 tpy de minimis 

threshold for PM2.5 and all PM2.5

precursors as a result of the EPA’s 

previous actions reclassifying the area 

as Serious nonattainment for the 1997 

annual and 24-hour PM2.5 NAAQS and 

the 2006 24-hour PM2.5 NAAQS.253

C. Statutory Deadline for Submission of 

Serious Area Plan 

When the EPA reclassifies a 

nonattainment area to a higher 

classification, the CAA sets the 

parameters for establishing deadlines for 

attainment plan SIP submissions for that 

higher classification. The State has 

already made submissions intended to 

address the Serious area attainment plan 

requirements for the 2012 PM2.5 NAAQS 

for the SJV, yet the EPA reclassification 

rulemaking must still establish the 

submission deadlines, as discussed in 

the following paragraphs. Among other 

things, such deadlines make clear the 

time frame for any future SIP 

submission should the State find the 

need to withdraw any particular 

element of the Serious area plan 

requirements (i.e., without the submittal 

of a replacement element meeting the 

completeness criteria). 

For an area reclassified as a Serious 

nonattainment area before the 

applicable attainment date under CAA 

section 188(b)(1), section 189(b)(2) 

requires the state to submit the required 

BACM provisions ‘‘no later than 18 

months after reclassification of the area 

as a Serious Area’’ and to submit the 

required attainment demonstration ‘‘no 

later than 4 years after reclassification of 

the area to Serious.’’ Section 189(b)(2) 

establishes outer bounds on the SIP 

submission deadlines as necessary or 

appropriate to assure consistency among 

the required submissions and to 

implement the statutory requirements. 

The Act provides the state with up to 

18 months after final reclassification of 

an area to Serious to submit the required 

BACM provisions. Because an up-todate emissions inventory serves as the 

foundation for a state’s BACM/BACT 

determination, the PM2.5 SIP 

Requirements Rule requires the state to 

submit the emissions inventory required 

under CAA section 172(c)(3) within 18 


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254 81 FR 58010, 58077. 

255Section 172(b) requires the EPA to establish, 

concurrent with nonattainment area designations, a 

schedule extending no later than three years from 

the date of the nonattainment designation for states 

to submit plans or plan revisions meeting the 

applicable requirements of sections 110(a)(2) and 

172(c) of the CAA. 

256 81 FR 58010, 58077. 

257 Id. at 58078. 

258Section 189(e) requires that the control 

requirements applicable to major stationary sources 

of PM2.5 also apply to major stationary sources of 

PM2.5 precursors, except where the state 

demonstrates to the EPA’s satisfaction that such 

sources do not contribute significantly to PM2.5

levels that exceed the standard in the area. 

259 ‘‘Indian country’’ as defined at 18 U.S.C. 1151 

refers to the following: ‘‘(a) all land within the 

limits of any Indian reservation under the 

jurisdiction of the United States Government, 

notwithstanding the issuance of any patent, and 

including rights-of-way running through the 

reservation, (b) all dependent Indian communities 

within the borders of the United States whether 

within the original or subsequently acquired 

territory thereof, and whether within or without the 

limits of a state, and (c) all Indian allotments, the 

Indian titles to which have not been extinguished, 

including rights-of-way running through the same.’’ 

months after the effective date of final 

reclassification.254 Similarly, because an 

effective evaluation of BACM/BACT 

measures requires evaluation of the 

precursor pollutants that must be 

controlled to provide for expeditious 

attainment in the area, if the state 

chooses to submit an optional precursor 

insignificance demonstration to support 

a determination to exclude a PM2.5

precursor from the required control 

measure evaluations for the area, the 

EPA requires that the state submit any 

such demonstration by this same date. 

An 18-month time frame for submission 

of these plan elements is consistent with 

both the time frame for submission of 

BACM/BACT provisions under CAA 

section 189(b)(2) and the time frame for 

submission of subpart 1 plan elements 

under section 172(b) of the Act.255

The PM2.5 SIP Requirements Rule also 

establishes a specific deadline for 

submission of the attainment 

demonstration and attainment-related 

plan elements following discretionary 

reclassification, which is the earlier of 

four years from the date of 

reclassification, or the end of the eighth 

calendar year after designation.256 In 

this case, the earlier of these two dates 

will be the end of the eighth calendar 

year after designation—i.e., December 

31, 2023. The attainment-related plan 

elements required within the same 

timeframe as the attainment 

demonstration are as follows: (1) The 

RFP demonstration required under 

section 172(c)(2); (2) the quantitative 

milestones required under section 

189(c); (3) any additional control 

measures necessary to meet the 

requirements of section 172(c)(6); and 

(4) the contingency measures required 

under section 172(c)(9). Although 

section 189(b)(2) generally provides for 

up to four years after a discretionary 

reclassification for the state to submit 

the required attainment demonstration, 

given the timing of this reclassification 

action less than two years before the 

Moderate area attainment date, it is 

appropriate in this case for the EPA to 

establish an earlier SIP submission 

deadline to assure timely 

implementation of the statutory 

requirements. 

Finally, the PM2.5 SIP Requirements 

Rule establishes a regulatory 

requirement that the state submit 

revised NNSR program requirements no 

later than 18 months after final 

reclassification.257 The Act does not 

specify a deadline for the state’s 

submission of SIP revisions to meet 

NNSR program requirements to lower 

the ‘‘major stationary source’’ threshold 

from 100 tpy to 70 tpy (CAA section 

189(b)(3)) and to address the control 

requirements for major stationary 

sources of PM2.5 precursors (CAA 

section 189(e)) 258 following 

reclassification of a Moderate PM2.5

nonattainment area as Serious 

nonattainment under subpart 4. 

Pursuant to the EPA’s gap-filling 

authority in CAA section 301(a) and to 

effectuate the statutory control 

requirements in section 189 of the Act, 

the PM2.5 SIP Requirements Rule 

requires the state to submit these NNSR 

SIP revisions, as well as any necessary 

analysis of and additional control 

requirements for major stationary 

sources of PM2.5 precursors, no later 

than 18 months after the effective date 

of final reclassification of the SJV as 

Serious nonattainment for the 2012 

PM2.5 standard. This due date will 

ensure that necessary control 

requirements for major sources are 

established in advance of the required 

attainment demonstration. An 18-month 

timeframe for submission of the NNSR 

SIP revisions also aligns with the 

statutory deadline for submission of 

BACM and BACT provisions and the 

broader analysis of PM2.5 precursors for 

potential controls on existing sources in 

the area. 

Accordingly, if we finalize our 

proposal to reclassify the SJV as a 

Serious nonattainment area for the 2012 

PM2.5 NAAQS, California would be 

required to submit the emissions 

inventory required under CAA section 

172(c)(3), the BACM/BACT provisions 

required under CAA section 

189(b)(1)(B), and any NNSR SIP 

revisions required to satisfy the 

requirements of CAA sections 189(b)(3) 

and 189(e) for the 2012 PM2.5 NAAQS 

no later than 18 months after the 

effective date of a final reclassification 

action. Additionally, California would 

be required to submit the Serious area 

attainment demonstration and all 

attainment-related plan elements no 

later than the end of the eighth calendar 

year after designation—i.e., by 

December 31, 2023. 

We note that the 2018 PM2.5 Plan 

submitted on May 10, 2019, includes a 

Serious area plan containing an 

attainment demonstration, emissions 

inventory, attainment-related plan 

elements, and BACM/BACT provisions. 

Also, the State submitted a SIP revision 

for the Serious area NNSR requirements 

on November 20, 2019. The EPA intends 

to evaluate and act on the Serious area 

plan and NNSR SIP submissions for the 

2012 PM2.5 NAAQS in the SJV through 

separate rulemakings, as appropriate. 

VI. Reclassification of Areas of Indian 

Country 

Eight Indian tribes are located within 

the boundaries of the SJV nonattainment 

area for the 2012 PM2.5 NAAQS. These 

tribes include Big Sandy Rancheria of 

Western Mono Indians of California, 

Cold Springs Rancheria of Mono Indians 

of California, Northfork Rancheria of 

Mono Indians of California, Picayune 

Rancheria of Chukchansi Indians of 

California, Santa Rosa Indian 

Community of the Santa Rosa 

Rancheria, California, Table Mountain 

Rancheria, Tejon Indian Tribe, and Tule 

River Indian Tribe of the Tule River 

Reservation, California. 

We have considered the relevance of 

our proposal to reclassify the SJV as 

Serious nonattainment for the 2012 

PM2.5 standard for each tribe located 

therein. We believe that the same facts 

and circumstances that support the 

proposal for the non-Indian country 

lands also support the proposal for 

reservation areas of Indian country 259

and any other areas of Indian country 

where the EPA or a tribe has 

demonstrated that the tribe has 

jurisdiction located within the SJV 

nonattainment area. The EPA is 

therefore proposing to exercise our 

authority under CAA section 188(b)(1) 

to reclassify areas of Indian country 

geographically located in the SJV 

nonattainment area. Section 188(b)(1) 

broadly authorizes the EPA to reclassify 

a nonattainment area—including any 

Indian country located within such an 

area—that the EPA determines cannot 

practicably attain the relevant standard 

by the applicable attainment date. 


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260CAA sections 189(b)(3) and 501(2)(B). 

261 40 CFR part 93, subpart B. 

262 81 FR 2993. 

263 Id. and 40 CFR 93.153(b). 

264We sent letters dated March 3, 2021, to tribal 

officials offering government-to-government 

consultation. See also a summary of the EPA’s 

outreach to tribes in the San Joaquin Valley; 

memorandum dated August 3, 2021, from Rory 

Mays, Air Planning Office, Air and Radiation 

Division, EPA Region IX, to Docket No. EPA–R09– 

OAR–2021–0543. We did not receive any request 

for consultation. 

265 85 FR 44192, at 44193 (July 22, 2020). 

266 2018 PM2.5 Plan, App. H (revised February 11, 

2020), H–24 to H–26. 

267Letter dated March 19, 2021, from Richard W. 

Corey, Executive Officer, CARB, to Deborah Jordan, 

Acting Regional Administrator, EPA Region IX, 

with enclosures. 

Directly-emitted PM2.5 and its 

precursor pollutants (i.e., NOX, SO2, 

VOC, and ammonia) are emitted 

throughout a nonattainment area and 

can be transported throughout that 

nonattainment area. Therefore, 

boundaries for nonattainment areas are 

drawn to encompass both areas with 

direct sources of the pollutant problem 

as well as nearby areas in the same 

airshed. Initial classifications apply to 

the entire nonattainment area, i.e., they 

exactly match the nonattainment area 

boundaries. The EPA believes this 

approach best ensures public health 

protection from the adverse effects of 

PM2.5 pollution. Therefore, it is 

generally counterproductive from an air 

quality and planning perspective to 

have a disparate classification for a land 

area located within the boundaries of a 

nonattainment area, such as the 

reservation areas of Indian country 

contained within the SJV PM2.5

nonattainment area. Violations of the 

2012 PM2.5 standard, which are 

measured and modeled throughout the 

nonattainment area, as well as shared 

meteorological conditions, would 

dictate the same conclusion. 

Furthermore, emission increases in 

portions of a PM2.5 nonattainment area 

that are left classified as Moderate could 

counteract the effects of efforts to attain 

the standard within the overall area 

because less stringent requirements 

would apply in those Moderate portions 

relative to those that would apply in the 

portions of the area reclassified to 

Serious. 

Uniformity of classification 

throughout a nonattainment area is thus 

a guiding principle and premise when 

an area is being reclassified. In this 

particular case, we are proposing to 

determine, based on the State’s 

demonstration and current ambient air 

quality trends, that the entire SJV 

nonattainment area, including all 

reservations areas of Indian country and 

any other area located within the SJV 

where a tribe has jurisdiction, cannot 

practicably attain the 2012 PM2.5

standard by the applicable Moderate 

area attainment date of December 31, 

2021. 

In light of the considerations outlined 

above that support retention of a 

uniformly-classified PM2.5

nonattainment area, and our proposal to 

find that it is impracticable for the area 

to attain by the applicable attainment 

date, we propose to reclassify the entire 

SJV nonattainment area, including 

reservation areas of Indian country and 

any other area of Indian country located 

within it where the EPA or a tribe has 

demonstrated that the tribe has 

jurisdiction, as Serious nonattainment 

for the 2012 PM2.5 standard. 

Generally, the effect of reclassification 

is to lower the applicable ‘‘major 

source’’ threshold for purposes of the 

NNSR program and the Title V 

operating permit program from 100 tpy 

to 70 tpy,260 thus subjecting additional 

new or modified stationary sources to 

these requirements. Reclassification also 

lowers the de minimis threshold under 

the CAA’s general conformity 

requirements from 100 tpy to 70 tpy.261

In this case, however, reclassification 

would not change the ‘‘major source’’ 

thresholds because, as a result of the 

EPA’s January 2016 reclassification of 

the SJV as a Serious nonattainment area 

for the 2006 PM2.5 NAAQS, the area is 

already subject to the 70 tpy major 

source threshold for Serious PM2.5

nonattainment areas in CAA section 

189(b)(3).262 Likewise, reclassification 

would have no impact on the applicable 

general conformity de minimis 

thresholds, because the SJV is already 

subject to the 70 tpy de minimis 

threshold for PM2.5 and all PM2.5

precursors as a result of the EPA’s 

previous reclassification of the area as 

Serious for the 2006 PM2.5 NAAQS.263

The EPA has contacted tribal officials 

to invite government-to-government 

consultation on this rulemaking 

effort.264 The EPA specifically solicits 

additional comment on this proposed 

rule from tribal officials. We note that 

although eligible tribes may seek EPA 

approval of relevant tribal programs 

under the CAA, none of the affected 

tribes will be required to submit an 

implementation plan as a result of this 

reclassification. 

VII. Review of Contingency Measure 

Element for the 2006 PM2.5 NAAQS 

A. Requirements for Contingency 

Measures 

With one exception, the SIP 

requirements for contingency measures 

that apply to areas classified as Serious 

for the 2006 PM2.5 NAAQS are the same 

as those described in section IV.H.1 of 

this document for areas that are 

classified as Moderate for the 2012 

PM2.5 NAAQS and cannot practicably 

attain the NAAQS by the statutory 

attainment date, and thus, are not 

repeated here. However, in addition to 

the contingency measures requirements 

that apply to Moderate areas with 

adequate impracticability 

demonstrations, states with areas 

classified as Serious must identify and 

adopt contingency measures to address 

the potential for the area to fail to attain 

the NAAQS by the applicable 

attainment date. 

B. Summary of State’s Contingency 

Measure Element for 2006 PM2.5

NAAQS 

The EPA deferred action on the 

contingency measure element of the 

2018 PM2.5 Plan for the 2006 PM2.5

NAAQS when we took final action on 

the other elements in the 2018 PM2.5

Plan for that NAAQS.265 In this section 

of this document, we are proposing 

action on the contingency measure 

element of the 2018 PM2.5 Plan for the 

2006 PM2.5 NAAQS. 

The 2018 PM2.5 Plan addresses the 

contingency measure requirement for 

the 2006 24-hour PM2.5 NAAQS by 

reference to the contingency measure 

portion of a December 2018 SIP 

submission that involved enhanced 

enforcement of CARB regulations in the 

SJV, a commitment to amend the 

District’s residential wood burning rule 

(i.e., District Rule 4901) to include 

contingent provisions, and updated 

emissions estimates for the year 

following the attainment year for use in 

evaluating whether the emissions 

reductions from the contingency 

measures are sufficient.266 Recently, 

CARB withdrew the enhanced 

enforcement portion of the December 

2018 SIP submission as it pertained to 

the 2006 PM2.5 NAAQS in the SJV.267

Accordingly, we have evaluated the 

relevant portions of the 2018 PM2.5 Plan 

and District Rule 4901 (specifically, 

section 5.7.3 of Rule 4901) for 

compliance with the applicable 

requirements for Serious areas for the 

2006 PM2.5 NAAQS. 

With respect to the District 

contingency measure, the 2018 PM2.5

Plan calls for the District to amend 

District Rule 4901 to include a 

requirement in the rule with a trigger 

that that would be activated should the 

EPA issue a final rulemaking that the 

SJV failed to meet a regulatory 

requirement necessitating 


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268Letter dated July 19, 2019, from Richard W. 

Corey, Executive Officer, CARB, to Mike Stoker, 

Regional Administrator, EPA Region IX. 269 85 FR 44206 (July 22, 2020) (final approval of 

District Rule 4901); 85 FR 1131, 1132–33 (January 

9, 2020) (proposed approval of District Rule 4901). 

270See Table B–13 in Appendix B from the 

District’s Final Staff Report (June 20, 2019) for 

revisions to Rule 4901. 

271NOX emissions reductions from the 

contingency measure are based on the District’s 

estimates for direct PM2.5 emissions using the ratio 

of direct PM2.5 to NOX in Table 1 of the District’s 

Final Staff Report (June 20, 2019) for revisions to 

Rule 4901. 

272 85 FR 44192, 44192. 273One year’s worth of RFP is based on the 

difference between the emissions estimates for 2013 

and 2024 in Table H–6 of Appendix H, divided by 

11 (i.e., the number of years from 2013 to 2024). 

implementation of a contingency 

measure. In response to the commitment 

made in the 2018 PM2.5 Plan, in June 

2019, the District adopted amendments 

to Rule 4901 including a contingency 

measure (in section 5.7.3 of the 

amended rule), and CARB submitted the 

amended rule to the EPA for approval 

as an attachment to a letter dated July 

19, 2019.268 The EPA has taken final 

action to approve amended Rule 4901, 

but in that approval, we noted that we 

were not evaluating the contingency 

measure in section 5.7.3 of revised Rule 

4901 for compliance with all 

requirements of the CAA and the EPA’s 

implementing regulations that apply to 

such measures.269 Rather, we approved 

the measure into the SIP because it 

strengthened the rule by providing a 

possibility of additional curtailment 

days, and thus potentially additional 

emissions reductions. We indicated that 

we would evaluate whether this 

provision, in conjunction with other 

submitted provisions, meets the 

statutory and regulatory requirements 

for contingency measures in future 

actions. In this proposal, we are now 

evaluating District Rule 4901, 

specifically, section 5.7.3, for 

compliance with the requirements for 

contingency measures for purposes of 

the 2006 PM2.5 NAAQS. 

District Rule 4901 is designed to limit 

emissions generated by the use of wood 

burning fireplaces, wood burning 

heaters, and outdoor wood burning 

devices. The rule establishes 

requirements for the sale/transfer, 

operation, and installation of wood 

burning devices and for advertising the 

sale of seasoned wood consistent with a 

moisture content limit within the SJV. 

The rule includes a two-tiered, 

episodic wood burning curtailment 

requirement that applies during four 

winter months, November through 

February. During a level one episodic 

wood burning curtailment, section 5.7.1 

prohibits any person from operating a 

wood burning fireplace or unregistered 

wood burning heater but permits the use 

of a properly operated wood burning 

heater that meets certification 

requirements and has a current 

registration with the District. Sections 

5.9 through 5.11 impose specific 

registration requirements on any person 

operating a wood burning fireplace or 

wood burning heater and section 5.12 

imposes specific certification 

requirements on wood burning heater 

professionals. During a level two 

episodic wood burning curtailment, 

operation of any wood burning device is 

prohibited by section 5.7.2. 

Prior to the 2019–2020 wood burning 

season, the District imposed a level one 

curtailment when the PM2.5

concentration was forecasted to be 

between 20–65 mg/m3 and imposed a 

level two curtailment when the PM2.5

concentration was forecasted to be 

above 65 mg/m3 or the PM10

concentration was forecasted to be 

above 135 mg/m3. In 2019, the District 

adopted revisions to Rule 4901 to lower 

the wood burning curtailment 

thresholds in the ‘‘hot spot’’ counties of 

Madera, Fresno, and Kern. The District 

lowered the level one PM2.5 threshold 

for these three counties from 20 mg/m3

to 12 mg/m3, and the level two PM2.5

threshold from 65 mg/m3 to 35 mg/m3. 

The District did not modify the 

curtailment thresholds for other 

counties in the SJV, and those levels 

remained at 20 mg/m3 for level one and 

65 mg/m3 for level two. 

The District’s 2019 revision to Rule 

4901 also included the addition of a 

contingency measure in section 5.7.3 of 

the rule, requiring that 60 days 

following the effective date of an EPA 

final rulemaking that the SJV has failed 

to attain the 1997, 2006, or 2012 PM2.5

NAAQS by the applicable attainment 

date, the PM2.5 curtailment levels for 

any county that has failed to attain the 

applicable standard will be lowered to 

the curtailment levels in place for hot 

spot counties. The District estimates 

that the potential emissions reduction in 

direct PM2.5 would be in the range of 

0.014 tpd (if the contingency is triggered 

in Kings County but not the other nonhot-spot counties) to 0.387 tpd (if the 

contingency is triggered in all five of the 

non-hot-spot counties), but there would 

be no emissions reduction if, at the time 

of the determination of failure to attain 

the 2006 PM2.5 NAAQS by the 

attainment date, violations of the 2006 

PM2.5 NAAQS were only observed at 

monitors in the hot-spot counties.270

Corresponding potential emissions 

reduction in NOX would be in the range 

of 0.002 tpd to 0.060 tpd, respectively, 

but as noted in the preceding 

paragraphs there may be no emissions 

reduction if the violations are monitored 

in the hot-spot counties only.271

The 2018 PM2.5 Plan also provides 

estimates of regional emissions in the 

year following the attainment year with 

which to evaluate the sufficiency of the 

emissions reductions from the 

contingency measure (i.e., section 5.7.3 

of Rule 4901). For the 2006 PM2.5

NAAQS, the attainment year is 2024 

and the year after the attainment year is 

therefore 2025.272 Based on Table H–5 

in the 2018 PM2.5 Plan, the annual 

average emission reductions from 2024 

to 2025 due to baseline measures and 

CARB and the District’s aggregate 

tonnage commitment are estimated to be 

0 tpd direct PM2.5 and 5.2 tpd NOX. For 

comparison purposes, one year’s worth 

of RFP (based on emissions estimates in 

the 2018 PM2.5 Plan) is approximately 

0.6 tpd direct PM2.5 and 18.4 tpd 

NOX.273

C. EPA Evaluation and Proposed Action 

For the 2006 PM2.5 NAAQS, we have 

similarly evaluated the contingency 

measure demonstration in the 2018 

PM2.5 Plan and associated contingency 

provision of the 2019 amendment to 

Rule 4901. Specifically, we have 

evaluated the contingency provision in 

District Rule 4901 (i.e., section 5.7.3 of 

the rule) against the requirements of 

CAA section 172(c)(9) and 40 CFR 

51.1014 for both attainment and RFP 

contingency measures, the latter of 

which also includes submittal of 

quantitation milestone reports and 

compliance with quantitative 

milestones. 

As noted in our summary of the 

State’s submission, the contingency 

provision in District Rule 4901 is 

structured to provide for 

implementation if the area fails to attain 

the 2006 PM2.5 NAAQS, not before, and 

is therefore consistent with CAA section 

172(c)(9). However, as structured by the 

District, the contingency provision of 

Rule 4901 (i.e., section 5.7.3) would 

provide for emissions reductions only in 

Kings, Merced, San Joaquin, Stanislaus, 

and/or Tulare counties, not the ‘‘hot 

spot’’ counties of Fresno, Kern, and 

Madera, and only if a violating 

monitoring site (i.e., a site where the 

collected data represent a violation of 

the NAAQS) is located in said county. 

In other words, if the EPA’s 

determination of failure to attain the 

NAAQS by the applicable attainment 

date indicates violations at monitoring 

location sites in Fresno and Kern (‘‘hot 

spot’’ counties) and Tulare (non-hotspot county) counties, the contingency 


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274Section 5.7.3 of Rule 4901 states that ‘‘the 

District shall notify the public of an Episodic 

Curtailment for the PM2.5 curtailment levels 

described in Sections 5.7.1.2 and 5.7.2.2 for any 

county that has failed to attain the applicable 

standard.’’ (emphasis added) We interpret this to 

mean that the District would apply the more 

stringent curtailment provisions for any county 

identified in the EPA’s final rule making the 

determination that the San Joaquin Valley failed to 

attain the applicable PM2.5 NAAQS. 

275We note that section 5.7.3 of District Rule 

4901 applies the lower thresholds ‘‘on and after 

sixty days following the effective date of EPA final 

rulemaking,’’ which is appropriate as a contingency 

measure trigger for a failure to attain by the 

applicable attainment date given that the EPA 

conducts rulemaking to make such determinations. 

However, for the three other contingency triggers, 

i.e., State failures to meet a quantitative milestone, 

submit a quantitative milestone report, or failure to 

meet an RFP requirement, the EPA may not conduct 

rulemaking but instead make the determinations 

through correspondence directly to the state. Thus, 

we recommend that section 5.7.3 of District Rule 

4901 be amended to refer to ‘‘EPA final 

determinations’’ rather than to ‘‘EPA final 

rulemaking’’ when the rule is amended to include 

the additional contingency measure triggers. 

276The EPA believes that the most 

straightforward remedy under these circumstances 

would be for the District to amend section 5.7.3 of 

Rule 4901 to extend the lower wood burning 

curtailment thresholds region-wide if the EPA 

determines that the area has failed to attain the 

2006 PM2.5 NAAQS by the applicable attainment 

date. 

277The calculation of one year’s worth of RFP is 

based on dividing the values in column E of table 

H–6 of Appendix H (updated February 11, 2020) of 

the 2018 PM2.5 Plan by 11, i.e., the number of years 

between 2013 and 2024. As part of the EPA’s final 

approval of the State’s attainment plan for the 2006 

PM2.5 NAAQS, we concluded that ammonia, SOX, 

and VOC emissions do not contribute significantly 

to ambient PM2.5 levels that exceed the 2006 PM2.5

NAAQS in the San Joaquin Valley. 85 FR 17382, at 

17390–17396 (March 27, 2020) (proposed rule); 

finalized at 85 FR 44192 (July 22, 2020). 

278These estimates are based on the annual 

average emission reductions from 2024 to 2025 due 

to baseline measures and CARB and the District’s 

aggregate tonnage commitment in Table H–5 of 

Appendix H (updated February 11, 2020) of the 

2018 PM2.5 Plan. We also note that Table H–13 of 

Appendix H indicates that the year-over-year 

reductions for purposes of the 2006 PM2.5 NAAQS 

is 0.1 tpd direct PM2.5 and 4.2 tpd NOX. However, 

the estimates in Table H–13 reflect emissions 

changes associated only with mobile sources 

whereas the appropriate comparison includes the 

entire emissions inventory. 

279 40 CFR 93.120(a)(3). 

provision would provide for emissions 

reductions by lowering the wood 

burning curtailment thresholds in only 

Tulare County. The ‘‘hot spot’’ counties 

are already subject to the lower wood 

burning curtailment thresholds in the 

rule and thus would not be affected by 

the finding of failure to attain 

determination and the other non-‘‘hot 

spot’’ counties (i.e., other than Tulare 

County in this example) would not be 

subject to the lower wood burning 

curtailment thresholds. 

In accordance with 40 CFR 51.1014, 

the contingency provision in District 

Rule 4901 identifies a specific triggering 

mechanism. In this case, the triggering 

mechanism in the rule is the EPA’s final 

determination that the SJV has failed to 

attain the 2006 PM2.5 NAAQS by the 

applicable attainment date.274 The rule 

also specifies a timeframe within which 

its requirements become effective after a 

failure-to-attain determination (i.e., on 

and after 60 days from the effective date 

of the EPA’s final determination), and 

would take effect with minimal further 

action by the state or the EPA. However, 

the contingency provision in District 

Rule 4901 does not address the potential 

for State failures to meet a quantitative 

milestone, submit a quantitative 

milestone report, or failure to meet an 

RFP requirement.275

In addition, the contingency measure 

provision of Rule 4901 is not structured 

to achieve any additional emissions 

reductions if the EPA finds that the 

monitoring locations in the ‘‘hot spot’’ 

counties (i.e., Fresno, Kern, or Madera 

Counties) are the only ones in the SJV 

that are violating the 2006 PM2.5

NAAQS as of the attainment date. To 

qualify as a contingency measure, a 

measure must be structured to achieve 

emissions reductions, if triggered, and 

the contingency provision of District 

Rule 4901 provides for such reductions 

only under certain circumstances and 

should be revised to provide for 

additional emissions reductions in the 

SJV (if triggered) regardless of which 

monitoring site(s) is determined to be 

violating the 2006 PM2.5 NAAQS as of 

the attainment date.276

Next, we considered the adequacy of 

the section 5.7.3 of District Rule 4901 

from the standpoint of the magnitude of 

emissions reductions the measures 

would provide (if triggered). Neither the 

CAA nor the EPA’s implementing 

regulations for the PM2.5 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 amounts 

to reductions of approximately 0.6 tpd 

of direct PM2.5 and 18.4 tpd of NOX for 

the 2006 PM2.5 NAAQS in the SJV.277

As noted in our summary of the State’s 

submission, the emissions reductions 

from the contingency provisions in 

District Rule 4901 would amount to 

approximately 0.00 tpd to 0.387 tpd of 

direct PM2.5, which equates to 

approximately 0% to 67% of one year’s 

worth of RFP for direct PM2.5. With 

respect to NOX emissions reductions, 

the contingency provisions in District 

Rule 4901 would amount to 

approximately 0.00 tpd to 0.06 tpd, 

which equates to approximately 0% to 

0.3% of one year’s worth of RFP for 

NOX. 

The State’s contingency measure 

element in the 2018 PM2.5 Plan provides 

the larger SIP planning context in which 

to judge the adequacy of the amount of 

emission reductions resulting from the 

contingency measure by calculating the 

surplus emissions reductions estimated 

to be achieved in the year after the 

attainment year. More specifically, the 

2018 PM2.5 Plan identifies additional 

NOX reductions in the year following 

the attainment year of 2024. For the SJV, 

the estimates of additional reductions in 

the post-attainment year (2025) are 0 tpd 

direct PM2.5 and 5.2 tpd NOX.278

Generally, we will consider such 

surplus emissions reductions in 

evaluating the sufficiency of the 

emissions reductions from contingency 

measures identified by the state, 

however, in this case, because the 

identified contingency measure may 

result in no emissions reductions, the 

larger planning context is not relevant to 

our review of the sufficiency of the 

contingency measure. 

For these reasons, we propose to 

disapprove the contingency measure 

element of the 2018 PM2.5 Plan under 

CAA section 179(c)(9) and 40 CFR 

51.1014 with respect to the State’s 

Serious area attainment plan for the 

2006 PM2.5 NAAQS in the SJV. While 

the contingency measure provision of 

the 2019 amendment to Rule 4901 has 

an adequate triggering mechanism for 

failure to attain, we propose to 

disapprove it because it may result in no 

emissions reductions if the area fails to 

attain the NAAQS by the applicable 

attainment date. Furthermore, as the 

contingency measure element and the 

contingency provision of Rule 4901 lack 

any to-be-triggered measure for failure 

to meet a quantitative milestone, submit 

a quantitative milestone report, or 

failure to meet an RFP requirement, we 

propose that the submission is also 

inadequate for RFP contingency 

measures. 

Lastly, if the EPA finalizes the 

proposed disapproval of the 

contingency measure element for the 

2006 PM2.5 NAAQS, the area would be 

eligible for a protective finding under 

the transportation conformity rule 

because the 2018 PM2.5 Plan reflects 

adopted control measures and contains 

enforceable commitments that fully 

satisfy the emissions reductions 

requirements for RFP and attainment for 

the 2006 PM2.5 NAAQS.279


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280 40 CFR 52.31. 

281 83 FR 62720. 

282 Id. 

283 85 FR 44192. 284 40 CFR 93.120(a)(2). 

VIII. Summary of Proposed Actions and 

Request for Public Comment 

Under CAA section 110(k)(3), the EPA 

is proposing to approve the following 

elements of the 2016 PM2.5 Plan and 

2018 PM2.5 Plan submitted by California 

to address the CAA’s Moderate area 

planning requirements for the 2012 

PM2.5 NAAQS in the SJV nonattainment 

area: 

1. The 2013 base year emissions 

inventories in the 2016 PM2.5 Plan, as revised 

in the 2018 PM2.5 Plan, as meeting the 

requirements of CAA section 172(c)(3) and 40 

CFR 51.1008(a); 

2. The reasonably available control 

measures/reasonably available control 

technology demonstration in the 2016 PM2.5

Plan, as supplemented in the 2018 PM2.5

Plan, as meeting the requirements of CAA 

sections 172(c)(1) and 189(a)(1)(C); 

3. The demonstration in the 2016 PM2.5

Plan that attainment by the Moderate area 

attainment date of December 31, 2021, is 

impracticable as meeting the requirements of 

CAA section 189(a)(1)(B)(ii) and 40 CFR 

51.1011(a); 

4. The reasonable further progress 

demonstration in the 2016 PM2.5 Plan, as 

revised in 2018 PM2.5 Plan, as meeting the 

requirements of CAA section 172(c)(2) and 40 

CFR 51.1012(a); 

5. The quantitative milestones in the 2016 

PM2.5 Plan, as revised in the 2018 PM2.5 Plan 

and the Valley State SIP Strategy, as meeting 

the requirements of CAA section 189(c) and 

40 CFR 51.1013(a)(1); and 

6. The motor vehicle emissions budgets for 

2022 in the 2018 PM2.5 Plan as shown in 

Table 6 of this proposed rule because they 

are derived from an approvable RFP 

demonstration and meet the requirements of 

CAA section 176(c) and 40 CFR part 93, 

subpart A. With respect to the budgets, we 

are proposing to limit the duration of the 

approval of the budgets to last only until the 

effective date of the EPA’s adequacy finding 

for any subsequently submitted budgets. We 

are proposing to do so at CARB’s request and 

in light of the benefits of using EMFAC2017- 

derived budgets prior to our taking final 

action on the future SIP revision that 

includes the updated budgets. 

Pursuant to CAA section 110(k)(3), 

the EPA proposes to disapprove the 

contingency measure element of the 

2016 PM2.5 Plan for the 2012 PM2.5

NAAQS, as revised in the 2018 PM2.5

Plan and supplemented by section 5.7.3 

of District Rule 4901, and the 

contingency measure element of the 

2018 PM2.5 Plan for the 2006 PM2.5

NAAQS, as supplemented by section 

5.7.3 of District Rule 4901, because, 

among other reasons, the elements 

include no specific measures to be 

undertaken if the state fails to submit a 

quantitative milestone report for the 

area, or if the area fails to meet RFP or 

a quantitative milestone. In addition, 

with respect to the contingency measure 

element in the 2018 PM2.5 Plan for the 

2006 PM2.5 NAAQS (as supplemented 

by section 5.7.3 of District Rule 4901), 

the element includes a specific measure 

that may not result in any emissions 

reductions following a failure to attain 

the 2006 PM2.5 NAAQS by the 

applicable attainment date under certain 

circumstances. 

If we finalize the disapproval of the 

contingency measure elements as 

proposed, the offset sanction in CAA 

section 179(b)(2) would apply in the SJV 

18 months after the effective date of a 

final disapproval, and the highway 

funding sanctions in CAA section 

179(b)(1) would apply in the area six 

months after the offset sanction is 

imposed.280 Neither sanction will be 

imposed under the CAA if the State 

submits and we approve, prior to the 

implementation of the sanctions, a SIP 

revision that corrects the deficiencies 

that we identify in our final action. The 

EPA intends to work with CARB and the 

SJVUAPCD to correct the deficiencies in 

a timely manner. 

In addition to the sanctions, CAA 

section 110(c)(1) provides that the EPA 

must promulgate a federal 

implementation plan (FIP) addressing 

any disapproved elements of the plan 

two years after the effective date of 

disapproval unless the State submits, 

and the EPA approves, the required SIP 

submittal. As a result of the EPA’s 

December 6, 2018 determination that 

California had failed to submit the 

required contingency measures for the 

2006 PM2.5 NAAQS and the 2012 PM2.5

NAAQS, among other required SIP 

submissions for the SJV,281 the EPA is 

already subject to a statutory deadline to 

promulgate a FIP for this purpose no 

later than two years after the effective 

date of that determination.282

Also, because we previously approved 

the Serious area plan RFP and 

attainment demonstrations and the 

motor vehicle emissions budgets for the 

2006 PM2.5 NAAQS,283 and because in 

this proposed rule we are proposing to 

approve the Moderate area plan RACM, 

additional reasonable measures, and 

RFP demonstrations, and motor vehicle 

emission budgets for the 2012 PM2.5

NAAQS, we are proposing to issue a 

protective finding under 40 CFR 

93.120(a)(3) to the disapproval of the 

contingency measures elements. 

Without a protective finding, the final 

disapprovals would result in a 

conformity freeze, under which only 

projects in the first four years of the 

most recent conforming Regional 

Transportation Plan (RTP) and 

Transportation Improvement Programs 

(TIP) can proceed. Generally, during a 

freeze, no new RTPs, TIPs, or RTP/TIP 

amendments can be found to conform 

until another control strategy 

implementation plan revision fulfilling 

the same CAA requirements is 

submitted, the EPA finds its motor 

vehicle emissions budget(s) adequate 

pursuant to § 93.118 or approves the 

submission, and conformity to the 

implementation plan revision is 

determined.284 Under a protective 

finding, the final disapproval of the 

contingency measures elements would 

not result in a transportation conformity 

freeze in the SJV PM2.5 nonattainment 

area and the MPOs may continue to 

make transportation conformity 

determinations. 

Finally, pursuant to CAA section 

188(b)(1), the EPA is proposing to 

reclassify the SJV PM2.5 nonattainment 

area, including reservation areas of 

Indian country and any other area 

where the EPA or a tribe has 

demonstrated that a tribe has 

jurisdiction within the SJV, as Serious 

nonattainment for the 2012 PM2.5

standard based on the agency’s 

determination that the SJV cannot 

practicably attain the standard by the 

Moderate area attainment date of 

December 31, 2021. Upon final 

reclassification as a Serious area, 

California will be required to submit, 

within 18 months after the effective date 

of the reclassification, an emissions 

inventory, provisions to assure that 

BACM shall be implemented no later 

than four years after the date of 

reclassification, and any NNSR SIP 

revisions required to satisfy the 

requirements of CAA sections 189(b)(3) 

and 189(e). California will also be 

required to submit, by December 31, 

2023, a Serious area plan that satisfies 

the requirements of part D of title I of 

the Act. This plan must include a 

demonstration that the SJV will attain 

the 2012 PM2.5 standard as 

expeditiously as practicable but no later 

than December 31, 2025, or by the most 

expeditious alternative date practicable 

and no later than December 31, 2030, in 

accordance with the requirements of 

CAA sections 189(b) and 188(e). 

We note that the 2018 PM2.5 Plan, 

submitted concurrently with the 2016 

PM2.5 Plan on May 10, 2019, includes a 

Serious area attainment demonstration, 

emissions inventory, attainment-related 

plan elements, and BACM/BACT 

provisions. The State also submitted a 

SIP submission for the Serious area 

NNSR requirements on November 20, 


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285We are establishing deadlines for submittal of 

SIP revisions that have already been submitted to 

timely address any elements that may be withdrawn 

in the future. 

2019. The EPA intends to evaluate and 

act on the Serious area plan and NNSR 

SIP submissions for the 2012 PM2.5

NAAQS in the SJV through separate 

rulemakings, as appropriate.285

In addition, because the EPA is 

proposing to similarly reclassify 

reservation areas of Indian country and 

any other area of Indian country where 

the EPA or a tribe has demonstrated that 

the tribe has jurisdiction within the SJV 

PM2.5 nonattainment area as Serious 

nonattainment for the 2012 PM2.5

standard, consistent with our proposed 

reclassification of the surrounding nonIndian country lands, the EPA has 

invited consultation with interested 

tribes concerning this issue. Although 

eligible tribes may seek the EPA’s 

approval of relevant tribal programs 

under the CAA, none of the affected 

tribes will be required to submit an 

implementation plan as a result of this 

reclassification. 

We will accept comments from the 

public on these proposals for the next 

30 days. The deadline and instructions 

for submission of comments are 

provided in the DATES and ADDRESSES

sections at the beginning of this 

proposed rule. 

IX. Statutory and Executive Order 

Reviews 

Additional information about these 

statutes and Executive Orders can be 

found at http://www.epa.gov/ 

lawsregulations/laws-and-executiveorders. 

A. Executive Order 12866: Regulatory 

Planning and Review, and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

The proposed actions are not a 

significant regulatory action and were 

therefore not submitted to the Office of 

Management and Budget (OMB) for 

review. 

B. Paperwork Reduction Act (PRA) 

The proposed actions do not impose 

an information collection burden under 

the PRA because they do not contain 

any information collection activities. 

C. Regulatory Flexibility Act (RFA) 

I certify that the proposed actions will 

not have a significant economic impact 

on a substantial number of small entities 

under the RFA. The proposed actions 

will not impose any requirements on 

small entities. This proposed rule would 

approve or disapprove State plans as 

meeting federal requirements and would 

not impose additional requirements 

beyond those imposed by State law. 

Additionally, the proposed rule would 

reclassify the SJV nonattainment area as 

Serious nonattainment for the 2012 

PM2.5 NAAQS and would not itself 

regulate small entities. 

D. Unfunded Mandates Reform Act 

(UMRA) 

The proposed actions do not contain 

an unfunded mandate of $100 million or 

more as described in UMRA, and does 

not significantly or uniquely affect small 

governments. This proposed rule would 

approve or disapprove State plans as 

meeting federal requirements and would 

not impose additional requirements 

beyond those imposed by State law. 

Additionally, the proposed rule would 

reclassify the SJV nonattainment area as 

Serious nonattainment for the 2012 

PM2.5 NAAQS and would not itself 

impose any federal intergovernmental 

mandate. The proposed actions would 

not require any tribe to submit 

implementation plans. 

E. Executive Order 13132: Federalism 

The proposed actions do not have 

federalism implications. They will not 

have substantial direct effects on the 

states, on the relationship between the 

national government and the states, or 

on the distribution of power and 

responsibilities among the various 

levels of government. 

F. Executive Order 13175: Coordination 

With Indian Tribal Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (65 FR 

67249, November 9, 2000), requires the 

EPA to develop an accountable process 

to ensure ‘‘meaningful and timely input 

by tribal officials in the development of 

regulatory policies that have tribal 

implications.’’ ‘‘Policies that have Tribal 

implications’’ is defined in the 

Executive Order to include regulations 

that have ‘‘substantial direct effects on 

one or more Indian tribes, on the 

relationship between the Federal 

government and the Indian tribes, or on 

the distribution of power and 

responsibilities between the Federal 

government and Indian Tribes.’’ 

Eight Indian tribes are located within 

the boundaries of the SJV nonattainment 

area for the 2012 PM2.5 NAAQS: The Big 

Sandy Rancheria of Western Mono 

Indians of California, the Cold Springs 

Rancheria of Mono Indians of 

California, the Northfork Rancheria of 

Mono Indians of California, the 

Picayune Rancheria of Chukchansi 

Indians of California, the Santa Rosa 

Indian Community of the Santa Rosa 

Rancheria, California, the Table 

Mountain Rancheria, the Tejon Indian 

Tribe, and the Tule River Indian Tribe 

of the Tule River Reservation, 

California. 

The EPA’s proposed actions on the 

SIP elements submitted by California to 

address the Moderate area requirements 

for the 2012 PM2.5 NAAQS and the 

contingency measure requirement for 

the 2006 PM2.5 NAAQS would not have 

tribal implications because 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 actions on the SIP 

submittals do not have tribal 

implications and will not impose 

substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175. 

The EPA has concluded that the 

proposed reclassification might have 

tribal implications for the purposes of 

Executive Order 13175, but would not 

impose substantial direct costs upon the 

tribes, nor would it preempt tribal law. 

The proposed reclassification from 

Moderate to Serious for a PM2.5 NAAQS 

would typically affect the EPA’s 

implementation of the new source 

review program because of the lower 

‘‘major source’’ threshold triggered by 

reclassification (70 tons per year for 

direct PM2.5 and precursors to PM2.5). 

However, because the SJV 

nonattainment area is already classified 

as Serious for the 1997 and 2006 PM2.5

NAAQS, the lower thresholds already 

apply within the nonattainment area, 

and the proposed reclassification from 

Moderate to Serious for the 2012 PM2.5

NAAQS would have no additional 

effect. The same is true for any tribal 

projects that require federal permits, 

approvals, or funding. Such projects are 

subject to the requirements of the EPA’s 

general conformity rule, and federal 

permits, approvals, or funding for the 

projects would typically become more 

difficult to obtain because of the lower 

de minimis thresholds triggered by 

reclassification but, in this case, the 

lower de minimis thresholds already 

apply within the SJV. 

Given the potential implications, the 

EPA contacted tribal officials during the 

process of developing this proposed rule 

to provide an opportunity to have 

meaningful and timely input into its 

development. On March 3, 2021, we 

sent letters to leaders of the eight tribes 

with areas of Indian country in the SJV 

nonattainment area inviting 

government-to-government consultation 

on the rulemaking effort. We requested 

that the tribal leaders, or their 


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Federal Register / Vol. 86, No. 167 / Wednesday, September 1, 2021 / Proposed Rules 49137 

designated consultation representatives, 

notify us of their interest in governmentto-government consultation by April 5, 

2021. We intend to continue 

communicating with all eight tribes 

located within the boundaries of the SJV 

nonattainment area for the 2012 PM2.5

NAAQS as we move forward in 

developing a final rule. The EPA 

specifically solicits additional comment 

on this proposed rule from tribal 

officials. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

The EPA interprets Executive Order 

13045 as applying only to those 

regulatory actions that concern 

environmental health or safety risks that 

the EPA has reason to believe may 

disproportionately affect children, per 

the definition of ‘‘covered regulatory 

action’’ in section 2–202 of the 

Executive Order. The proposed rule is 

not subject to Executive Order 13045 

because it would approve or disapprove 

a State plan implementing a federal 

standard, and reclassify the SJV 

nonattainment area as Serious 

nonattainment for the 2012 PM2.5

NAAQS, triggering Serious area 

planning requirements under the CAA. 

This proposed action does not establish 

an environmental standard intended to 

mitigate health or safety risks. 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This proposed rule is not subject to 

Executive Order 13211, because it is not 

a significant regulatory action under 

Executive Order 12866. 

I. National Technology Transfer and 

Advancement Act 

This rulemaking does not involve 

technical standards. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Population 

The EPA has determined that the 

proposed actions will not have potential 

disproportionately high and adverse 

human health or environmental effects 

on minority or low-income populations 

because they do not affect the level of 

protection provided to human health or 

the environment. The proposed actions 

would only approve or disapprove State 

plans implementing a federal standard, 

and reclassify the SJV nonattainment 

area as Serious nonattainment for the 

2012 PM2.5 NAAQS, triggering 

additional Serious area planning 

requirements under the CAA. 

List of Subjects 

40 CFR Part 52 

Environmental protection, Air 

pollution control, Ammonia, 

Incorporation by reference, 

Intergovernmental relations, Nitrogen 

dioxide, Particulate matter, Reporting 

and recordkeeping requirements, Sulfur 

dioxide, Volatile organic compounds. 

40 CFR Part 81 

Environmental protection, Air 

pollution control, Particulate matter. 

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

Dated: August 25, 2021. 

Elizabeth Adams, 

Acting Regional Administrator, Region IX. 

[FR Doc. 2021–18764 Filed 8–31–21; 8:45 am] 

BILLING CODE 6560–50–P 


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