33528 Federal Register / Vol. 86, No. 120 / Friday, June 25, 2021 / Rules and Regulations 

In addition, the SIP is not approved 

to apply on any Indian reservation land 

or in any other area where EPA or an 

Indian tribe has demonstrated that a 

tribe has jurisdiction. In those areas of 

Indian country, the rule does not have 

tribal implications and will not impose 

substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this action and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). 

Under section 307(b)(1) of the CAA, 

petitions for judicial review of this 

action must be filed in the United States 

Court of Appeals for the appropriate 

circuit by August 24, 2021. Filing a 

petition for reconsideration by the 

Administrator of this final rule does not 

affect the finality of this action for the 

purposes of judicial review nor does it 

extend the time within which a petition 

for judicial review may be filed, and 

shall not postpone the effectiveness of 

such rule or action. This action may not 

be challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2) of the CAA.) 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Nitrogen dioxide, Sulfur 

oxides. 

Dated: June 14, 2021. 

Cheryl Newton, 

Acting Regional Administrator, Region 5. 

For the reasons stated in the 

preamble, EPA amends 40 CFR part 52 

as follows: 

PART 52—APPROVAL AND 

PROMULGATION OF 

IMPLEMENTATION PLANS 

■ 1. The authority citation for part 52 

continues to read as follows: 

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

■ 2. In § 52.720, the table in paragraph 

(c) is amended under ‘‘Part 225: Control 

of Emissions From Large Combustion 

Sources’’, ‘‘Subpart B: Control of 

Mercury Emissions From Coal-Fired 

Electric Generating Units’’ by revising 

the entry for ‘225.233’ to read as 

follows: 

§ 52.720 Identification of plan. 

* * * * * 

(c) * * * 

EPA-APPROVED ILLINOIS REGULATIONS AND STATUTES

Illinois citation Title/subject 

State 

effective 

date 

EPA approval date Comments 

*******

Part 225: Control of Emissions From Large Combustion Sources 

*******

Subpart B: Control of Mercury Emissions From Coal-Fired Electric Generating Units 

225.233 ....................... Multi-Pollutant Standard (MPS) ................... 8/23/2019 6/25/2021, [INSERT FEDERAL 

REGISTER CITATION].

Except (c), (d), and 

(i). 

* * * * * * * 

* * * * * 

[FR Doc. 2021–13431 Filed 6–24–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R09–OAR–2019–0709; FRL–10025– 

14–Region 9] 

Approval of Air Quality Implementation 

Plans; California; Eastern Kern; 8-Hour 

Ozone Nonattainment Area 

Requirements 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is taking final action to 

approve, or conditionally approve, all or 

portions of three state implementation 

plan (SIP) revisions submitted by the 

State of California to meet Clean Air Act 

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

2008 8-hour ozone national ambient air 

quality standards (NAAQS or 

‘‘standards’’) in the Eastern Kern, 

California (‘‘Eastern Kern’’) ozone 

nonattainment area. In this action, the 

EPA refers to these submittals 

collectively as the ‘‘2017 Eastern Kern 

Ozone SIP.’’ The 2017 Eastern Kern 

Ozone SIP addresses certain 

nonattainment area requirements for the 

2008 ozone NAAQS, including the 

requirements for an emissions 

inventory, attainment demonstration, 

reasonable further progress, reasonably 

available control measures, contingency 

measures, among others; and establishes 

motor vehicle emissions budgets. The 

EPA is taking final action to approve the 

2017 Eastern Kern Ozone SIP as meeting 

all the applicable ozone nonattainment 

area requirements except for the 

contingency measure requirement, for 

which the EPA is taking final action to 

conditionally approve, and the 

reasonably available control measures 

and attainment demonstration 

requirements, for which the EPA is 

deferring action at this time. 

DATES: This rule will be effective on July 

26, 2021. 

ADDRESSES: The EPA has established a 

docket for this action under Docket ID 

No. EPA–R09–OAR–2019–0709. All 


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1 85 FR 68268. Eastern Kern is located on the 

western edge of the Mojave Desert, separated from 

populated valleys and coastal areas to the west and 

south by several mountain ranges. For a precise 

description of the geographic boundaries of the 

Eastern Kern ozone nonattainment area, see 40 CFR 

81.305. 

2Submitted by letter dated October 25, 2017, 

from Richard W. Corey, Executive Officer, CARB, to 

Alexis Strauss, Acting Regional Administrator, EPA 

Region IX. 

3Submitted electronically on December 11, 2018 

as an attachment to a letter dated December 5, 2018 

from Richard W. Corey, Executive Officer, CARB, to 

Mike Stoker, Regional Administrator, EPA Region 

IX. 

4Submitted electronically on August 31, 2020, as 

an attachment to a letter dated August 25, 2020, 

from Richard W. Corey, Executive Officer, CARB, to 

John Busterud, Regional Administrator, EPA Region 

IX. 

5 Ground-level ozone pollution is formed from the 

reaction of volatile organic compounds (VOC) and 

oxides of nitrogen (NOX) in the presence of 

sunlight. The 1-hour ozone NAAQS is 0.12 parts 

per million (ppm) (one-hour average), the 1997 

ozone NAAQS is 0.08 ppm (eight-hour average), 

and the 2008 ozone NAAQS is 0.075 ppm (eighthour average). CARB refers to reactive organic gases 

(ROG) in some of its ozone-related submittals. The 

CAA and the EPA’s regulations refer to VOC, rather 

than ROG, but both terms cover essentially the same 

set of gases. In this final rule, we use the term (VOC) 

to refer to this set of gases. 

6On May 15, 2021, CARB requested that the EPA 

voluntarily reclassify Eastern Kern to ‘‘Severe’’ for 

the 2008 ozone NAAQS, and we approved the 

reclassification to Severe on June 7, 2021 (86 FR 

30204), with a new attainment date of July 20, 2027. 

7South Coast Air Quality Management Dist. v. 

EPA, 882 F.3d 1138 (D.C. Cir. 2018). The term 

‘‘South Coast II’’ is used in reference to the 2018 

court decision to distinguish it from a decision 

published in 2006 also referred to as ‘‘South Coast.’’ 

The earlier decision involved a challenge to the 

EPA’s Phase 1 implementation rule for the 1997 

ozone standard. South Coast Air Quality 

Management Dist. v. EPA, 472 F.3d 882 (D.C. Cir. 

2006). 

8 In a letter dated December 18, 2019, from 

Richard W. Corey, Executive Officer, CARB, to 

Michael Stoker, Regional Administrator, EPA 

Region 9, CARB requested withdrawal of the RFP 

demonstration included in the Eastern Kern 2017 

Ozone Plan submitted in October 2017. The RFP 

demonstration in the 2018 SIP Update replaced the 

demonstration in the Eastern Kern 2017 Ozone 

Plan. 

documents in the docket are listed on 

the https://www.regulations.gov 

website. Although listed in the index, 

some information is not publicly 

available, e.g., Confidential Business 

Information (CBI) or other information 

whose disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available through https:// 

www.regulations.gov, or please contact 

the person identified in the FOR FURTHER

INFORMATION CONTACT section for 

additional availability information. 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: John 

Ungvarsky, Air Planning Office (AIR–2), 

EPA Region IX, 75 Hawthorne Street, 

San Francisco, CA 94105, (415) 972– 

3963 or ungvarsky.john@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Summary of the Proposed Action 

II. Public Comments and EPA Responses 

III. Final Action 

IV. Statutory and Executive Order Reviews 

I. Summary of the Proposed Action 

On October 28, 2020, the EPA 

proposed to approve, under Clean Air 

Act (CAA) section 110(k)(3), and to 

conditionally approve, under CAA 

section 110(k)(4), all or portions of three 

submittals from the California Air 

Resources Board (CARB) and the 

Eastern Kern Air Pollution Control 

District (EKAPCD or ‘‘District’’) as 

revisions to the California SIP for the 

Eastern Kern ozone nonattainment 

area.1 The three SIP revisions include 

the ‘‘2017 Ozone Attainment Plan For 

2008 Federal 75 ppb 8-Hour Ozone 

Standard’’ (‘‘Eastern Kern 2017 Ozone 

Plan’’),2 the Eastern Kern portion of the 

‘‘2018 Updates to the California State 

Implementation Plan’’ (‘‘2018 SIP 

Update’’),3 and the ‘‘Transportation 

Conformity Budget State 

Implementation Plan Update for the 

Eastern Kern 2017 Ozone Attainment 

Plan’’ (‘‘2020 Conformity Budget 

Update’’).4 Collectively, we refer to the 

relevant portions of the three SIP 

revisions as the ‘‘2017 Eastern Kern 

Ozone SIP,’’ and we refer to our October 

28, 2020 proposed rule as the ‘‘proposed 

rule.’’ 

In our proposed rule, we provided 

background information on the ozone 

standards,5 area designations, related 

SIP revision requirements under the 

CAA, and the EPA’s implementing 

regulations for the 2008 ozone 

standards, referred to as the 2008 Ozone 

SIP Requirements Rule (‘‘2008 Ozone 

SRR’’). To summarize, at the time of our 

proposed rule, the Eastern Kern ozone 

nonattainment area was classified as 

‘‘Serious’’ for the 2008 ozone NAAQS, 

and the 2017 Eastern Kern Ozone SIP 

was developed to address the statutory 

and regulatory requirements for 

revisions to the SIP for the Eastern Kern 

Serious ozone nonattainment area.6

In our proposed rule, we also 

discussed a decision issued by the D.C. 

Circuit Court of Appeals in South Coast 

Air Quality Management Dist. v. EPA 

(‘‘South Coast II’’) 7 that vacated certain 

portions of the EPA’s 2008 Ozone SRR. 

The only aspect of the South Coast II 

decision that affects this action is the 

vacatur of the provision in the 2008 

Ozone SRR that allowed states to use an 

alternative baseline year for 

demonstrating reasonable further 

progress (RFP). To address this, in the 

2018 SIP Update, CARB submitted an 

updated RFP demonstration that relied 

on a 2011 baseline year as required.8

For our proposed rule, we reviewed 

the various SIP elements contained in 

the 2017 Eastern Kern Ozone SIP (other 

than the reasonably available control 

measures (RACM) demonstration or the 

attainment demonstration), evaluated 

them for compliance with statutory and 

regulatory requirements, and concluded 

that they meet all applicable 

requirements, except for the 

contingency measure requirement, for 

which the EPA proposed conditional 

approval. More specifically, in our 

proposal rule, we based our proposed 

actions on the following determinations: 

• CARB and the District met all 

applicable procedural requirements for 

public notice and hearing prior to the 

adoption and submittal of the Eastern 

Kern 2017 Ozone Plan, 2018 SIP 

Update, and 2020 Conformity Budget 

Update (see 85 FR 68271 from the 

proposed rule); 

• The 2012 base year emissions 

inventory from the Eastern Kern 2017 

Ozone Plan is comprehensive, accurate, 

and current and thereby meets the 

requirements of CAA sections 172(c)(3) 

and 182(a)(1) and 40 CFR 51.1115 for 

the 2008 ozone NAAQS. Additionally, 

the future year baseline projections 

reflect appropriate calculation methods 

and the latest planning assumptions and 

are properly supported by the SIPapproved stationary and mobile source 

measures (see 85 FR 68271–68273, 

68274–68276 from the proposed rule); 

• The emissions statement element of 

the Eastern Kern 2017 Ozone Plan, 

including District Rule 108.2 (‘‘Emission 

Statement Requirements’’) meets the 

requirements for emissions statements 

under CAA section 182(a)(3)(B) and 40 

CFR 51.1102 for the 2008 ozone NAAQS 

(see 85 FR 68273–68274 from the 

proposed rule); 

• The 15 percent rate-of-progress 

(ROP) demonstration element in the 

Eastern Kern 2017 Ozone Plan meets the 

requirements of CAA section 182(b)(1) 

for the Eastern Kern ozone 

nonattainment area for the 2008 ozone 

NAAQS based on the previouslyapproved ROP demonstration for the 


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9See Eastern Kern 2017 Ozone Plan, 33, and 62 

FR 1150, 1172 (January 8, 1997); clarified at 84 FR 

45422 (August 29, 2019). 

10Letter dated November 26, 2019, from Gwen 

Yoshimura, Manager, Air Quality Analysis Office, 

EPA Region IX, to Ravi Ramalingam, Chief, 

Consumer Products and Air Quality Assessment 

Branch, Air Quality Planning and Science Division, 

CARB. 

11 In the proposed rule, we found that the clean 

fuels fleet program requirement in CAA sections 

182(c)(4) and 246 and 40 CFR 51.1102 had been met 

in Eastern Kern through previous EPA approval of 

the 1994 ‘‘Opt-Out Program’’ SIP revision. Upon 

reconsideration, we now recognize that the clean 

fuels fleet program requirement does not apply to 

Eastern Kern as a reclassified Serious 

nonattainment area for the 2008 ozone NAAQS 

because the 1980 population of Eastern Kern was 

below 250,000, and as such, the area does not meet 

the population-based applicability threshold for the 

requirement under CAA section 246(a)(3). 

12Bahr v. EPA, 836 F.3d 1218 (9th Cir. 2016) 

(‘‘Bahr’’) (rejecting early-implementation of 

contingency measures and concluding that a 

contingency measure under CAA section 172(c)(9) 

must take effect at the time the area fails to make 

RFP or attain by the applicable attainment date, not 

before). 

13Letter dated September 1, 2020, from Glen E. 

Stephens, Air Pollution Control Officer, EKAPCD, 

to Richard Corey, Executive Officer, CARB. 

14Letter dated September 18, 2020, from Richard 

W. Corey, Executive Officer, CARB, to John 

Busterud, Regional Administrator, EPA Region IX. 

15CAA section 171(1) defines reasonable further 

progress as ‘‘such annual incremental reductions in 

emissions of the relevant air pollutant as are 

required by this part or may reasonably be required 

by the Administrator for the purpose of ensuring 

attainment of the applicable national ambient air 

quality standard by the applicable date.’’ The words 

‘‘this part’’ in the statutory definition of RFP refer 

to part D of title I of the CAA, which contains both 

the general requirements in subpart 1 and the 

pollutant-specific requirements in subparts 2–5 

(including the ozone-specific RFP requirements in 

CAA sections 182(b)(1) and 182(c)(2)(B) for Serious 

areas). 

Eastern Kern 9 1-hour ozone 

nonattainment area (see 85 FR 68274– 

68276 from the proposed rule); 

• The RFP demonstration in the 2018 

SIP Update, as corrected in the 2020 

Conformity Budget Update, provides for 

emissions reductions of VOC or NOX of 

at least 3 percent per year on average for 

each three-year period from a 2011 

baseline year through the attainment 

year and thereby meets the requirements 

of CAA sections 172(c)(2) and 

182(c)(2)(B), and 40 CFR 

51.1110(a)(2)(ii) for the 2008 ozone 

NAAQS (see 85 FR 68274–68276 from 

the proposed rule); 

• The motor vehicle emissions 

budgets in the 2020 Conformity Budget 

Update for the RFP milestone/ 

attainment year of 2020 are consistent 

with the RFP demonstration, are clearly 

identified and precisely quantified, and 

meet all other applicable statutory and 

regulatory requirements in 40 CFR 

93.118(e), including the adequacy 

criteria in 40 CFR 93.118(e)(4) and (5) 

(see 85 FR 68279–68280 from the 

proposed rule); and 

• Through previous EPA approvals of 

the 1993 Photochemical Assessment 

Monitoring Station SIP revision and the 

‘‘Annual Network Plan Covering 

Monitoring Operations in 25 California 

Air Districts, July 2019’’ with respect to 

the Eastern Kern element,10 we find that 

the enhanced monitoring requirements 

under CAA section 182(c)(1) and 40 

CFR 51.1102 for Eastern Kern have been 

met with respect to the 2008 ozone 

NAAQS (see 85 FR 68280–68282 from 

the proposed rule).11

In our proposed rule, in light of the 

Bahr decision,12 we determined that the 

contingency measures element of the 

2017 Eastern Kern Ozone SIP could not 

be fully approved without 

supplementation by the District and 

CARB. However, we also determined 

that the element could be conditionally 

approved as meeting the requirements 

of CAA sections 172(c)(9) and 182(c)(9) 

for the 2008 ozone NAAQS, based upon 

commitments by the District 13 and 

CARB 14 to supplement the element 

through submission, as a SIP revision 

(within one year of our final conditional 

approval action), of a revised District 

rule or rules that would add new limits 

or other requirements if an RFP 

milestone is not met or if Eastern Kern 

fails to attain the 2008 ozone NAAQS by 

the applicable attainment date. See 85 

FR 68276–68279 from the proposed 

rule. 

Please see our proposed rule for more 

information concerning the background 

for this action and for a more detailed 

discussion of the rationale for approval 

or conditional approval of the abovelisted elements of the 2017 Eastern Kern 

Ozone SIP. 

II. Public Comments and EPA 

Responses 

The public comment period on the 

proposed rule opened on October 28, 

2020, the date of its publication in the 

Federal Register, and closed on 

November 27, 2020. During this period, 

the EPA received one comment letter 

submitted by Air Law for All on behalf 

of the Center for Biological Diversity 

(referred to herein as ‘‘CBD’’ or 

‘‘commenter’’). We address CBD’s 

comments in the following paragraphs 

of this final rule. 

Comment #1: Citing certain statutory 

provisions and selected excerpts from 

the EPA’s implementation rules for the 

1997 and 2008 ozone NAAQS, CBD 

asserts that, for Serious areas, the RFP 

demonstration must meet both the 

general RFP requirements in section 

172(c)(2) that are tied to attainment of 

the ozone standards and the specific 

RFP requirements in section 182(c)(2)(B) 

for reductions in emissions of VOCs 

from baseline emissions. In short, CBD 

contends that the RFP ‘‘targets’’ cannot 

be severed from the attainment 

demonstration and control strategy and 

independently approved, and because 

the EPA has not proposed to approve an 

attainment demonstration and control 

strategy for the Eastern Kern 

nonattainment area, there is no basis to 

conclude that the RFP demonstration in 

the 2017 Eastern Kern Ozone SIP meets 

the general RFP requirements in section 

172(c)(2). 

Response to Comment #1: As CBD 

notes, Serious ozone nonattainment 

areas are subject to both the general 

requirements for nonattainment plans in 

subpart 1, and the specific requirements 

for ozone areas in subpart 2, including 

the requirements related to RFP and 

attainment. This is consistent with the 

structure of the CAA as modified under 

the 1990 amendments, which 

introduced additional subparts to part D 

of title I of the CAA to address 

requirements for specific NAAQS 

pollutants, including ozone (subpart 2), 

carbon monoxide (CO) (subpart 3), 

particulate matter (subpart 4), and sulfur 

oxides, nitrogen dioxide, and lead 

(subpart 5). 

These subparts apply tailored 

requirements for these pollutants, 

including those based on an area’s 

designation and classification, in 

addition to and often in place of the 

generally applicable provisions retained 

in subpart 1. While CAA section 

172(c)(2) of subpart 1 states only that 

nonattainment plans ‘‘shall require 

reasonable further progress,’’ CAA 

sections 182(b)(1) and 182(c)(2)(B) of 

subpart 2 provide specific percent 

reduction targets for ozone 

nonattainment areas to meet the RFP 

requirement. Put another way, subpart 2 

further defines RFP for ozone 

nonattainment areas by specifying the 

incremental amount of emissions 

reduction required by set dates for those 

areas.15 For Moderate ozone 

nonattainment areas, CAA section 

182(b)(1) defines RFP by setting a 

specific 15% VOC reduction 

requirement over the first six years of 

the plan. For Serious and above ozone 

nonattainment areas, CAA section 

182(c)(2)(B) defines RFP by setting 

specific annual percent reductions for 

the period following the first six-year 

period and allows averaging over a 3- 

year period. With respect to the 1-hour 

ozone NAAQS, the EPA stated that, by 

meeting the specific percent reduction 

requirements in CAA sections 182(b)(1) 

and 182(c)(2)(B), the State will also 


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16 57 FR 13498, at 13510 (Moderate areas) and at 

13518 (Serious areas) (April 16, 1992). 

17 70 FR 71612 (November 29, 2005). 

18 80 FR 12264 (March 6, 2015). Under 40 CFR 

51.919 and 51.1119, the regulations promulgated 

through the 2008 Ozone SRR replaced the 

regulations promulgated through the Phase 2 rule, 

with certain exceptions not relevant here. 

19Compare the RFP requirements for the 1997 

ozone NAAQS at 40 CFR 51.910(a)(1)(ii)(A) and 

(b)(2)(ii)(C) with the analogous provisions for the 

2008 ozone NAAQS at 40 CFR 51.1110(a)(2)(i)(B). 

20 40 CFR 51.1100(t). 

21 83 FR 62998 (December 6, 2018). 

22 40 CFR 51.1300(l). 23 40 CFR 51.1110(a)(2) applies to Eastern Kern 

because Eastern Kern is an area with an approved 

1-hour ozone NAAQS 15 percent VOC Rate of 

Progress (ROP) plan. 24 85 FR 68268, at 68274–68276. 

25Excerpt from CBD comments (see page 10) 

citing ‘‘The Role of Ozone Precursors in 

Tropospheric Ozone Formation and Control: A 

Report to Congress,’’ EPA–454/R–93–024, at 2–2 

(July 1993), EPA Office of Air Quality Planning and 

Standards (report to Congress mandated by section 

185B, 42 U.S.C. 7511f). 

satisfy the general RFP requirements of 

section 172(c)(2) for the time period 

discussed.16

We agree with CBD that the EPA has 

adapted the RFP requirements under the 

CAA to implement the three 8-houraverage ozone NAAQS that have been 

promulgated since the 1990 CAA 

Amendments. In the ‘‘Phase 2’’ SIP 

Requirements Rule 17 for the 1997 

Ozone NAAQS (‘‘Phase 2 rule’’), the 

Agency adapted the RFP requirements 

of CAA sections 172(c)(2) and 182(a)(1) 

so as to require plans to provide for the 

minimum required percent reductions 

and, for certain Moderate areas, to 

provide for the reductions as necessary 

for attainment. See, e.g., 40 CFR 

51.910(a)(1)(ii)(A) and (b)(2)(ii)(C). 

In 2015, the EPA replaced the 

regulations promulgated through the 

Phase 2 rule with the regulations 

promulgated through the 2008 Ozone 

SIP Requirements Rule (SRR).18 In the 

2008 Ozone SRR, the EPA established 

RFP requirements for the 2008 ozone 

NAAQS that are similar, in most 

respects, to those in the Phase 2 rule for 

the 1997 ozone NAAQS but that do not 

carry forward the aspect of the RFP 

requirement for the 1997 ozone NAAQS 

that defined RFP for certain years for 

certain Moderate areas in terms of the 

reductions needed for attainment.19

More explicitly, in the 2008 Ozone SRR, 

the EPA defined RFP as meaning both 

the ‘‘emissions reductions required 

under CAA section 172(c)(2) which the 

EPA interprets to be an average 3 

percent per year emissions reductions of 

either VOC or NOX and CAA sections 

182(c)(2)(B) and (c)(2)(C) and the 15 

percent reductions over the first six 

years of the plan and the following three 

percent per year average under 40 CFR 

51.1110.’’ 20 (emphasis added). Thus, 

under the 2008 Ozone SRR, the RFP 

emissions reductions required for 

Serious and above ozone nonattainment 

areas under CAA section 172(c)(2) are 

based on a set annual percentage found 

in the CAA, not on the specific 

attainment needs for the area. In this 

regard, we have been even more explicit 

in our SRR for the 2015 ozone 

NAAQS: 21 ‘‘Reasonable further progress 

(RFP) means the emissions reductions 

required under CAA sections 172(c)(2), 

182(c)(2)(B), 182(c)(2)(C), and § 51.1310. 

The EPA interprets RFP under CAA 

section 172(c)(2) to be an average 3 

percent per year emissions reduction of 

either VOC or NOX.’’ 22

In the 2008 Ozone SRR, which is the 

set of regulations that governs the EPA’s 

action here, RFP is defined in terms of 

percent reduction requirements, not in 

terms of the reductions necessary for 

attainment. In other words, for the 2008 

ozone NAAQS, the RFP ‘‘targets’’ 

represent the minimum progress that is 

required under the CAA and our 

regulations, not necessarily all of the 

reductions necessary to achieve 

attainment of the ozone NAAQS, which 

could vary largely from one 

nonattainment area to another. 

Eastern Kern is a Serious 

nonattainment area for the 2008 ozone 

NAAQS, and the RFP demonstration in 

the 2017 Eastern Kern Ozone SIP was 

developed to meet the applicable 

requirements of the CAA and our 2008 

Ozone SRR, not the Phase 2 rule for the 

1997 ozone NAAQS. Specifically, we 

reviewed the RFP demonstration in the 

2017 Eastern Kern Ozone SIP for 

compliance with the requirements 

under 40 CFR 51.1110(a)(2)(i), which 

adapts the requirements under CAA 

sections 172(c)(2) and 182(b)(1) for 

Moderate areas, and 40 CFR 

51.1110(a)(2)(ii), which adapts the 

requirements of CAA section 

182(c)(2)(B) for Serious areas.23 The 

requirements under 40 CFR 

51.1110(a)(2)(i) and 40 CFR 

51.1110(a)(2)(ii) are cumulative and, 

together, they require a 15 percent 

emission reduction from the baseline 

year within 6 years after the baseline 

year and an average emissions reduction 

of 3 percent per year for all remaining 

3-year periods after the first 6-year 

period until the year of the area’s 

attainment date. As explained further in 

our proposed rule, based on our 

evaluation, we found that the 2017 

Eastern Kern Ozone SIP provided for the 

percent reductions required under the 

2008 Ozone SRR.24

Importantly, under the 2008 Ozone 

SRR, the RFP demonstration for the 

2008 ozone NAAQS does not need to 

provide for the reductions needed for 

attainment. Thus, contrary to CBD’s 

assertion, the RFP demonstration for 

Eastern Kern can be severed from the 

attainment demonstration and control 

strategy and can be independently 

approved, and we do so in this final rule 

by taking final action to approve the 

RFP demonstration in the 2017 Eastern 

Kern Ozone SIP while deferring action 

on the attainment demonstration. 

Comment #2: CBD comments that the 

submittal fails to show that the 

substitute NOX emissions reductions 

will ‘‘result in a reduction in ozone 

concentrations at least equivalent’’ to 

the required three percent per annum 

VOC emissions reductions, and as a 

result, the EPA’s proposed approval of 

the RFP demonstration is arbitrary and 

capricious. 

The commenter describes the relative 

roles of VOC and NOX in ozone 

formation, including the existence of an 

‘‘optimum’’ VOC to NOX ratio for a 

given level of VOC (i.e., a NOX

concentration at which the maximum 

amount of ozone is produced). As 

explained by the commenter, in a ‘‘NOX

saturated’’ situation where NOX levels 

exceed this optimum ratio, a reduction 

in NOX emissions can lead to increases 

in ozone levels, whereas in a ‘‘NOX

limited’’ situation with NOX levels 

below the optimum ratio, a reduction in 

NOX emissions decreases ozone levels. 

The commenter quotes the EPA’s report 

to Congress as including, ‘‘ozone 

response to precursor control can vary 

greatly with each area’’ and ‘‘the relative 

effectiveness of controls of volatile 

organic compounds (VOCs) and oxides 

of nitrogen (NOX) in ozone abatement 

varies widely.’’ 25 The commenter 

argues that language in the CAA, 

including CAA sections 185B, 182(f), 

and 182(c)(2)(C), indicates that Congress 

was aware of the issue of the relative 

roles of NOX and VOC in ozone 

formation, including that in some 

scenarios NOX reductions may actually 

increase ozone concentrations or at least 

not help to reduce ozone 

concentrations. 

The commenter then points to the 

EPA’s consideration of the relative 

effectiveness of NOX and VOC controls 

for interpollutant offset trading under 

the new source review (NSR) permitting 

program and in applying requirements 

for major stationary sources of VOC to 

NOX sources under CAA section 182(f), 

noting that in these situations EPA 

guidance indicates that photochemical 

grid modeling of multiple scenarios 

should be conducted to support 

demonstrations related to the relative 


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26Eastern Kern 2017 Ozone Plan, Appendix F, F– 

42—F–43; and Appendix H, H–22—H–23. 

27 Id. 

28Eastern Kern 2017 Ozone Plan, Appendix F, 

Figure 14, F–42. 

29The use of ‘‘NOX-limited’’ in the 2017 Eastern 

Kern Ozone SIP is mainly consistent with NOX

reductions being more effective than VOC 

reductions, i.e., ‘‘NOX-limited’’ in a relative sense 

rather than the strict sense of ozone decreasing with 

NOX reductions. See Appendix F of the Eastern 

Kern 2017 Ozone Plan: ‘‘(NOX-limited region in 

Figure 13), ozone formation shows a benefit to 

reductions in NOX emissions, while changes in 

ROG emissions result in only minor decreases in 

ozone,’’ F–40; in Figure 13, the ‘‘NOX-limited’’ 

region is one with isopleth lines nearly parallel to 

the VOC axis, indicating little change in ozone as 

VOC changes, and relatively large changes in ozone 

as NOX changes, F–41; ‘‘This region [Eastern Kern] 

is in close proximity to biogenic ROG emissions 

effectiveness of controls. Through 

comparison of the contexts of these 

guidance documents, which 

recommended photochemical modeling, 

and that of section 182(c)(2)(C), the 

commenter suggests that the 2017 

Eastern Kern Ozone SIP should have 

included similar photochemical grid 

modeling to determine whether the 

substitute NOX emission reductions 

result in equivalent ozone reductions. 

Response to Comment #2: In general, 

we agree with the commenter’s 

descriptions of the relative roles of VOC 

and NOX in ozone formation and 

geographic differences in the ozone 

response to precursor control, 

depending on whether an area is ‘‘NOXsaturated’’ or ‘‘NOX-limited.’’ We also 

agree with the commenter that Congress 

was aware of these issues and provided 

for the EPA to address them under 

provisions of the CAA. 

However, we disagree with the 

commenter’s characterization of the 

2017 Eastern Kern Ozone SIP and the 

EPA’s proposed approval. While the 

preamble of the EPA’s proposed 

approval did not provide an analysis 

showing that NOX substitution would 

‘‘result in a reduction in ozone 

concentrations at least equivalent’’ to 

the required VOC emissions reductions 

needed for RFP, the supporting 

documentation in the docket for the 

proposed approval, as further clarified 

in our response to comments herein, 

provides such analysis. As described 

below, we find that the analysis 

included with the modeling and control 

strategy in the 2017 Eastern Kern Ozone 

SIP adequately demonstrates that 

annual and cumulative NOX reductions 

in Eastern Kern will result in a 

reduction in ozone concentrations that 

is at least equivalent to the ozone 

reductions that would be achieved by 

VOC emission reductions alone. We 

therefore agree with the use of NOX

substitution in the RFP demonstration 

for Eastern Kern. 

Under CAA section 182(c)(2)(B), the 

RFP demonstration for a Serious ozone 

nonattainment area will demonstrate 

RFP based solely on the prescribed 

annual rate of VOC emission reductions. 

Alternatively, under CAA section 

182(c)(2)(C), the demonstration may 

satisfy the RFP requirement based on a 

combination of VOC and NOX

reductions if it demonstrates that 

reductions of VOC and NOX would 

result in a reduction in ozone 

concentrations at least equivalent to that 

which would result from the amount of 

VOC emission reductions otherwise 

required. For Eastern Kern, the RFP 

demonstration for milestone years 2017 

and 2020 both rely on a combination of 

VOC reductions and NOX reductions 

from the RFP baseline year of 2011. 

The revised RFP demonstration in the 

2018 SIP Update, as corrected in the 

2020 Conformity Budget Update, shows 

the extent to which the area is relying 

on NOX emissions reductions to 

substitute for otherwise-required VOC 

reductions in milestone years 2017 and 

2020. For milestone year 2017, the RFP 

demonstration relies on a combination 

of 1.4 tons per day (tpd) VOC reductions 

and 0.4 tpd NOX reductions from the 

2011 RFP baseline year rather than the 

otherwise-required VOC reductions of 

1.6 tpd. That is, 0.4 tpd of NOX

reductions substitutes for 0.2 tpd of 

VOC reductions otherwise required, 

which represents a 2:1 ratio for 

substitution of NOX for VOC in RFP 

milestone year 2017. This substitution 

of NOX reductions for VOC reductions 

is acceptable under CAA section 

182(c)(2)(C) so long as the ozone 

concentration reductions from 2011 to 

2017 in Eastern Kern under the 

combined VOC/NOX emissions 

reduction scenario are at least 

equivalent to that which would result 

under the VOC-only reduction scenario. 

The same applies to milestone year 

2020. For that year, the RFP 

demonstration relies on a combination 

of 1.5 tpd VOC reductions and 3.1 tpd 

NOX reductions from the 2011 RFP 

baseline year rather than the otherwiserequired VOC reductions of 2.3 tpd. 

That is, 3.1 tpd of NOX reductions 

substitutes for 0.8 tpd of VOC 

reductions otherwise required, which 

means that NOX is substituted for VOC 

in RFP milestone year 2020 at roughly 

a 4:1 ratio. Again, this substitution of 

NOX reductions for VOC reductions is 

acceptable under CAA section 

182(c)(2)(C) so long as the ozone 

concentration reductions from 2011 to 

2020 in Eastern Kern under the 

combined VOC/NOX emissions 

reduction scenario are at least 

equivalent to that which would result 

under the VOC-only reduction scenario. 

The 2017 Eastern Kern Ozone SIP 

contains a demonstration supporting the 

use of NOX substitution in the Eastern 

Kern nonattainment area. This is based 

on evidence that the Eastern Kern 

nonattainment area is NOX-limited, and 

also on evidence that NOX reductions 

are more effective at reducing ozone 

than VOC reductions alone. In this 

notice, we use ‘‘NOX-limited’’ as 

meaning a situation where reducing 

NOX emissions decreases ozone, not 

that it is more effective than reducing 

VOC. Elsewhere, including in the 2017 

Eastern Kern Ozone SIP, the term ‘‘NOXlimited’’ is sometimes used to mean the 

condition where NOX reductions are 

more effective than VOC reductions at 

decreasing ozone. 

Evidence that the Eastern Kern 

nonattainment area is NOX-limited is 

presented in Figure 14 in Appendix F of 

the Eastern Kern 2017 Ozone Plan. 

Figure 14 and the explanatory text 

document weekday and weekend 

monitored ozone data at the Mojave 

monitoring site from 2000–2015.26 The 

results show that in nearly all years, 

weekdays with their higher NOX

emissions have increased ozone, while 

weekends with their lower NOX, have 

decreased ozone. Figure 14 includes a 

1:1 line on which weekday and 

weekend ozone are the same.27 Of the 

sixteen years examined, thirteen are 

above the 1:1 line, indicating higher 

weekday ozone and NOX-limited ozone 

formation. All years after 2007 are above 

the 1:1 line. The three years (i.e., 2001, 

2003, and 2007) below the 1:1 line 

indicate slightly higher ozone from 

reducing NOX. However, all three of 

those years are in the ‘‘transitional’’ 

regime close to the 1:1 line; this 

indicates the three years have only a 

weak ozone response to NOX

reductions, as opposed to a disbenefit. 

This data analysis is strong evidence 

that ozone formation is NOX-limited in 

the Eastern Kern nonattainment area. 

The Eastern Kern 2017 Ozone Plan 

also included photochemical modeling 

results reflecting base year (2012) 

emissions and meteorology. The 

weekday-weekend analysis discussed 

above was repeated for modeled 

concentrations, which were found to be 

‘‘NOX-limited.’’ 28 The degree of NOXlimitation, that is the response of ozone 

to NOX emissions reductions, was found 

to be comparable to and somewhat 

greater than that in the ambient data. 

Given the Eastern Kern 2017 Ozone 

Plan’s usage of the term ‘‘NOX-limited,’’ 

the photochemical modeling also 

indicates that NOX reductions are more 

effective than VOC at reducing ozone.29


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sources and farther away from the anthropogenic 

NOX sources, such that low NOX and high ROG 

reactivity conditions are prevalent, which is 

consistent with the region being in a NOX-limited 

regime,’’ F–42. The CARB Staff Report on the 

Eastern Kern 2017 Ozone Plan (see A–9 of the Staff 

Report) refers to NOX-limited conditions as 

discussed in Finlayson-Pitts and Pitts, 1993, p.1093, 

whose use of ‘‘NOX-limited’’ is consistent with both 

the relative and strict senses of the term, but given 

its context of ‘‘control of VOCs versus NOX,’’ is 

more relevant to the relative sense. 

30Eastern Kern 2017 Ozone Plan, Appendix H, 

H–8—H–15; CARB Staff Report on the Eastern Kern 

2017 Ozone Plan, A–5. 

31Eastern Kern 2017 Ozone Plan, Appendix H, 

H–20. 

32The VOC:NOX ratio increases due to chemical 

conversion to HNO3 and due to the process of 

deposition to surfaces, which removes NOX (in the 

form of HNO3) from the air more quickly than VOC. 

Barbara J. Finlayson-Pitts and James N. Pitts Jr., 

1993, ‘‘Atmospheric Chemistry of Tropospheric 

Ozone Formation: Scientific and Regulatory 

Implications,’’ Journal of the Air and Waste 

Management Association, 43:8, 1091–1100, https:// 

doi.org/10.1080/1073161X.1993.10467187; cited in 

CARB Staff Report, p. A–9. 

33Eastern Kern 2017 Ozone Plan, Appendix H, 

H–21. 

34Eastern Kern 2017 Ozone Plan, Table 14, 37. 

35 85 FR 68268, 68275–68276. 

36Eastern Kern 2017 Ozone Plan, Appendix H, 

H–22. As already noted, the 2017 Eastern Kern 

Ozone SIP primarily uses ‘‘NOX-limited’’ to mean 

NOX reduction are more effective than VOC 

reductions. ‘‘SJVAB’’ is an acronym for the San 

Joaquin Valley Air Basin. 

37CARB Staff Report on the Eastern Kern 2017 

Ozone Plan, A–9, A–13—A–18. 

38SJV 2016 Ozone Plan, San Joaquin Valley 

Unified Air Pollution Control District, June 16, 

2016. 

39 2018 SIP Update, CARB, October 25, 2018. 

40 84 FR 3302 (February 12, 2019). 

41SJV 2016 Ozone Plan, Appendix H, Figure 15, 

H–54. Clovis is located in Fresno County, 

approximately 7 miles northeast of downtown 

Fresno. 

42Email dated October 19, 2018, from Sylvia 

Vanderspek, CARB to Anita Lee, EPA Region IX, 

with attachments. 

43 83 FR 61346 (November 29, 2018); See also the 

related final rule at 84 FR 11198 (March 25, 2019). 

44 ‘‘Technical Support Document, Proposed Phase 

2 Approval of Portions of the SJV 2016 Ozone Plan 

and 2018 SIP Updates,’’ Docket: EPA–R09–OAR– 

2018–0535, EPA Region 9, November 14, 2018, 

including two attachments: ‘‘Scale attainment 

demonstration with updated emissions’’ and ‘‘Effect 

of Updated Emissions Estimates on San Joaquin 

Valley Attainment Demonstration.’’ 

45 Id. 

46Eastern Kern 2017 Ozone Plan, H–16. 

For a percentage-based NOX

substitution to result in an equivalent 

ozone reduction, ozone formation must 

not only be NOX-limited, but also NOX

reductions must be at least as effective 

at reducing ozone as VOC reductions. In 

the 2017 Eastern Kern Ozone SIP, CARB 

and the District concluded that ozone 

formation is ‘‘NOX-limited,’’ but again, 

they use that term to mean that NOX

reductions are more effective than VOC 

reductions. That conclusion was based 

not only on the weekday-weekend 

evidence of NOX limitation but also on 

additional information, as described in 

the following paragraphs. 

The 2017 Eastern Kern Ozone SIP also 

provides ample documentation that 

high ozone concentrations in Eastern 

Kern are mainly due to transport from 

the San Joaquin Valley (SJV) to the 

northwest and sometimes from the 

South Coast Air Basin (SCAB) to the 

southwest.30 Further, NOX and VOC 

emissions in the western Kern County 

portion of the SJV are respectively 2.5 

and 8 times those within Eastern Kern; 

NOX and VOC emissions in the Los 

Angeles County portion of SCAB are 

respectively 10 and 37 times those 

within Eastern Kern.31 Eastern Kern is 

downwind of large urban areas, and 

CARB noted in the 2017 Eastern Kern 

Ozone SIP the recognized phenomenon 

that locations downwind of major urban 

areas have high VOC:NOX ratios and 

consequently are more sensitive to NOX

reduction than to VOC. The VOC:NOX

ratio of an urban air mass tends to 

increase as it moves downwind, since 

there is less input of NOX emissions 

from combustion sources but continued 

VOC emissions input from biogenic 

sources, and also NOX gets 

preferentially removed by other 

chemical and physical processes.32 In 

Eastern Kern, biogenic VOC emissions 

are 10 times as high as anthropogenic 

VOC in 2005 and upwards of 20 times 

as high during peak biogenic years,33

which also tends to increase the 

VOC:NOX ratio in Eastern Kern. 

EKAPCD estimated biogenic VOC 

emissions to be 169 tpd during the 

period of 2012 through 2020,34 which is 

over five times the total baseline NOX

inventories used in the RFP 

demonstration in Table 3.35 CARB states 

in the 2017 Eastern Kern Ozone SIP that 

‘‘This region is in close proximity to 

biogenic ROG emissions sources and 

farther away from the large 

anthropogenic NOX sources in the 

SJVAB and SCAB, such that low NOX

and high ROG conditions are prevalent, 

which is consistent with a NOX-limited 

regime.’’ 36 While some of this evidence 

could be termed qualitative, the EPA 

finds that it makes a compelling case 

that NOX emissions reductions are more 

effective than VOC reduction at 

decreasing ozone in Eastern Kern, and 

therefore that percentage-based NOX

substitution results in ozone reductions 

at least equivalent to those that would 

result from the VOC reductions required 

for RFP. 

The 2017 Eastern Kern Ozone SIP 

clearly documents that the Eastern Kern 

nonattainment area is strongly affected 

by transport of ozone from the SJV and 

SCAB.37 Although the EPA’s proposed 

action did not discuss in detail the 

impact of transport on RFP, we are 

providing additional technical 

information to further clarify the 

relationship between transport from the 

SJV and SCAB and ozone formation in 

the Eastern Kern nonattainment area. 

Photochemical modeling results in 

the ‘‘2016 Ozone Plan for 2008 8-Hour 

Ozone Standard for the San Joaquin 

Valley’’ (‘‘SJV 2016 Ozone Plan’’) 38 and 

analyses of the San Joaquin Valley 

portion of the ‘‘2018 Updates to the 

California State Implementation Plan’’ 

(‘‘2018 SIP Update’’) 39 also support the 

conclusion that NOX reductions are 

more effective than VOC at reducing 

ozone in the Eastern Kern 

nonattainment area. The EPA approved 

a modeled attainment demonstration for 

the SJV 2016 Ozone Plan that used the 

same meteorological and photochemical 

models, model domains, and setup 

parameters, and covered the same 2012 

ozone season as the Eastern Kern 

modeling.40 The SJV 2016 Ozone Plan 

contained an ozone isopleth diagram for 

the Clovis monitor,41 the SJV site with 

the highest ozone design value in 2031. 

In support of the 2018 SIP Update, 

CARB provided supplemental 

documentation that used the isopleth 

diagram to show that the SJV attainment 

demonstration remained valid.42 As part 

of the EPA’s approval of the SJV portion 

of the 2018 SIP Update,43 the EPA used 

the ozone isopleth diagram to estimate 

the sensitivity of ozone to VOC and NOX

emissions reductions.44 We determined 

that ozone changes by 0.313 ppb per 

percent change in NOX emissions, and 

by 0.0234 ppb per percent change in 

VOC emissions.45 On a percentage basis, 

NOX is 13.4 times as effective as VOC 

at reducing ozone at the Clovis monitor. 

The ozone response to emission changes 

is expected to be similar in western 

Kern County because both areas have 

similar meteorological conditions and a 

similar mix of emissions sources. 

Eastern Kern is directly downwind of 

western Kern County. The mountain 

ranges to the northwest separate 

sparsely populated Eastern Kern from 

the more densely populated areas in the 

southern SJV, including western Kern 

County. However, the Tehachapi pass 

connects the SJV to Eastern Kern, 

facilitating the transport of emissions 

and pollutants into the region.46 For the 

reasons discussed earlier in this section, 

ozone formation in Eastern Kern is more 

NOX-limited than the larger urban areas 

of the southern SJV and western Kern 

County. Putting these together, ozone in 

Eastern Kern is expected to be 13 times 

or more as sensitive to NOX emissions 


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47San Joaquin Valley Unified Air Pollution 

Control District, ‘‘2007 Ozone Plan,’’ April 30, 2007. 

The EPA approved the 2007 Ozone Plan at 77 FR 

12652 (March 1, 2012). 

48 Id. in Appendix F. Photochemical Modeling 

Support Documents, F–15—F–58. 

49Eastern Kern 2017 Ozone Plan, Appendix F, F– 

15. 

50South Coast 2016 AQMP, Appendix V, 

Attachment 4 (2031 8-Hour Ozone Isopleths), 21; 

and Attachment 5 (2023 8-Hour Ozone Isopleths), 

21. 

51See EPA, ‘‘Guideline for Determining the 

Applicability of Nitrogen Oxide Requirements 

under Section 182(f)’’ (December 16, 1993), 1; 

Memorandum dated January 14, 2005, from 

Stephen D. Page, Director, Office of Air Quality 

Planning and Standards, U.S. EPA, to EPA Regional 

Air Directors, Regions I–X, Subject: ‘‘Guidance on 

Limiting Nitrogen Oxides (NOX) Requirements 

Related to 8-Hour Ozone Implementation,’’ 3; EPA– 

454/R–18–004, ‘‘Technical Guidance for 

Demonstration of Inter-Precursor Trading (IPT) for 

Ozone in the Nonattainment New Source Review 

Program,’’ Office of Air Quality Planning and 

Standards (May 2018) (‘‘IPT Guidance’’), 2. The IPT 

Guidance specifically excludes applicability to RFP 

demonstrations. IPT Guidance at 2, n.1. 

reductions as to VOC reductions on a 

percentage basis. 

In addition, the 2007 Ozone Plan for 

San Joaquin Valley included isopleth 

diagrams for every monitoring site, 

including those in Kern County, just 

upwind of Eastern Kern.47 The State 

used photochemical modeling to assess 

the effect of NOX and VOC emissions 

reductions for projected years 2020 and 

2023 at every site. For every location for 

both years, NOX emissions reductions 

were more effective than VOC at 

reducing ozone. For example, the 

projected 2020 8-hour ozone design 

value at the Bakersfield-California 

Avenue site was modeled to decrease 

from 87 to 86 ppb when VOC is reduced 

by 20 percent, and from 87 to 83 ppb 

when NOX is reduced by 20 percent. 

The corresponding values for 2023 are 

a decrease from 88 to 87 ppb for VOC, 

and a decrease from 88 to 84 ppb for 

NOX.48 This is additional evidence that 

NOX reductions are more effective than 

VOC reductions in Eastern Kern. 

Air quality in the Eastern Kern 

nonattainment area is also strongly 

affected by ozone transport from the 

SCAB through the Soledad Canyon 

located between Santa Clarita in the 

SCAB and Palmdale, south of Eastern 

Kern.49 Santa Clarita is approximately 

65 miles from the Mojave monitor and 

approximately 50 miles from the 

southern boundary of the nonattainment 

area. In the South Coast Air Quality 

Management District’s (SCAQMD’s) 

‘‘Final 2016 Air Quality Management 

Plan’’ (‘‘South Coast 2016 AQMP’’), 

SCAQMD included an isopleth for the 

Santa Clarita monitoring site.50 The 

isopleths for the Santa Clarita site 

clearly show that NOX reductions in the 

area upwind of Eastern Kern are more 

effective than VOC reductions at 

reducing ozone. 

The documentation associated with 

the Clovis and Santa Clarita monitors, 

representative locations in the SJV and 

SCAB upwind of the mountain passes 

through which ozone is transported to 

downwind Eastern Kern, demonstrates 

that NOX reductions are more effective 

than VOC reductions in the Eastern 

Kern nonattainment area. This further 

supports the conclusion that NOX

substitution results in a reduction in 

ozone concentrations at least equivalent 

to that which would result from the 

amount of VOC emission reductions 

otherwise required for RFP. Even 

though the State’s submittal lacks an 

isopleth diagram specifically for the 

Mojave site in Eastern Kern, the 

supporting documentation (i.e., Figure 

14; the comparison of Eastern Kern 

emissions with emissions from western 

Kern County and Los Angeles County; 

VOC emissions from biogenic sources; 

and isopleths from upwind sites in the 

SJV and SCAB) demonstrates that the 

resulting NOX reductions here will be at 

least equivalent to that which would 

result from VOC reductions alone, as 

required in section 182(c)(2)(C). 

Based on the above, we disagree with 

the commenter’s assertion that CAA 

section 182(c)(2)(C) requires the District 

to provide additional photochemical 

grid modeling to demonstrate that the 

substituted NOX reductions are at least 

as effective as the VOC reductions that 

would otherwise be required under 

section 182(c)(2)(B). 

Further, we believe that the 

commenter’s comparison to the EPA’s 

recommendations with respect to 

interpollutant trading for nonattainment 

NSR permitting purposes and eligibility 

for an exemption from NOX

requirements under CAA 182(f) are not 

relevant for NOX substitution under 

CAA section 182(c)(2)(C). The guidance 

documents cited by the commenter for 

these examples are non-binding and do 

not constrain the EPA’s discretion to 

adopt a different approach where 

appropriate.51 The documents 

recommend photochemical grid 

modeling in some scenarios but do not 

require this approach or any other 

specific demonstration. This reflects the 

EPA’s acknowledgement that the level 

of analysis required for any particular 

demonstration related to NOX and VOC 

reductions will differ based on context 

and local conditions, such as those 

noted by the commenter regarding the 

relative effectiveness of controlling 

each. In the context of CAA 182(c)(2)(C) 

and based on the EPA’s responses 

herein, no additional modeling or 

demonstration is required. 

Comment #3: The commenter also 

contends that an equivalence 

demonstration under CAA section 

182(c)(2)(C) must show equivalence 

throughout the nonattainment area, 

must be quantitative, and must be as 

technically rigorous as an attainment 

demonstration. 

First, the commenter states that 

because CAA section 182(c)(2)(C) uses 

the plural ‘‘ozone concentrations,’’ the 

equivalency demonstration must show 

equivalence throughout the 

nonattainment area, and not just at a 

single monitoring site. Otherwise, there 

could be ozone increases in NOXsaturated areas within the 

nonattainment area that might interfere 

with attainment of the more stringent 

2015 ozone NAAQS, and that might 

result in adverse public health effects 

even for locations meeting the ozone 

NAAQS because there is no safe level of 

ozone. 

Second, the commenter criticizes the 

technical information in the Eastern 

Kern 2017 Ozone Plan as insufficient to 

show that NOX substitution will result 

in equivalent reductions in ozone 

concentrations throughout the 

nonattainment area. The commenter 

states that the Eastern Kern 2017 Ozone 

Plan submittal documents the ozone 

decrease from weekend NOX reductions 

at a single Mojave monitor during 2000– 

2015 to conclude the area is NOXlimited, and that it makes general 

observations about the magnitude and 

distance of emissions. The commenter 

states that the technical information in 

the Eastern Kern 2017 Ozone Plan is 

merely qualitative, whereas the word 

‘‘equivalent’’ in CAA section 

182(c)(2)(C) means that the 

demonstration should be quantitative. 

The commenter also states that the 2017 

Eastern Kern Ozone SIP should consider 

post-2015 data, because of post-2015 

emissions changes like the replacement 

of NOX combustion sources with wind 

and solar electricity generation, and 

because of the changing geographic 

distribution of emissions. 

Lastly, the commenter states that an 

equivalence demonstration should be as 

rigorous as an attainment 

demonstration, which is based on 

photochemical modeling or another 

equally rigorous technique. The 

commenter suggests that the state could 

compare modeled relative response 

factors (RRFs) for each RFP milestone 

year for the 3 percent per year VOC 

reductions to corresponding factors 

from the control strategy. Alternatively, 

for the demonstration, the commenter 

suggests that the state could use ozone 


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52Eastern Kern 2017 Ozone Plan, Appendix A. 

53CARB Staff Report on Eastern Kern 2017 Ozone 

Plan, A–8. 

54This is an approximation based on SJV NOX

and VOC emissions in tons per day as shown in the 

bar chart in CARB Staff Report on the Eastern Kern 

2017 Ozone Plan (see A–8); SJV is the area most 

often upwind of Eastern Kern, and its 

photochemical modeling includes both areas. The 

VOC:NOX ratios increase because NOX declines 

more than VOC. Specifically the VOC:NOX ratios 

for 2010, 2015, and 2020, respectively are 380/400 

= 0.95, 315/267 = 1.18, and 300/205 = 1.46, an 

increasing sequence that spans the 2012–2020 

period. Another estimate can be made using the SJV 

emissions from the 2016 SJV Ozone Plan. The 

summer tons per day VOC:NOX emissions ratio 

increases from 337.3/339.6 = 0.99 in 2012 to 300.2/ 

212.7 = 1.41 in 2020. 

isopleth diagrams together with 

conservative assumptions about the 

amount of allowable NOX substitution. 

Response to Comment #3: First, we 

disagree that the plural 

‘‘concentrations’’ in CAA section 

182(c)(2)(C) necessarily means that 

equivalence must be demonstrated 

throughout the nonattainment area. 

However, in this instance, it does not 

matter because all locations within the 

Eastern Kern nonattainment area are 

downwind of, and more NOX-limited 

than, the SJV and the SCAB, for which 

NOX reductions are more effective than 

VOC. Therefore, NOX reductions are 

more effective than VOC for all 

locations in the Eastern Kern 

nonattainment area. 

Second, we disagree that equivalence 

demonstrations necessarily must be 

quantitative estimates. Analytical 

information that establishes equivalence 

may be quantitative or qualitative, or 

both, depending on the facts and 

circumstances of any given area. In this 

instance, as discussed above, some of 

the evidence relied upon could be 

termed qualitative, such as the known 

tendency for ozone formation to become 

more NOX-limited with distance 

downwind of an urban area, and the 

relative sizes of emissions inventories 

for Eastern Kern and the upwind areas. 

This relatively qualitative evidence was 

coupled with more quantitative 

assessments of the degree of NOXlimitation (weekday-weekend 

differences). Qualitative evidence can be 

just as useful as quantitative evidence. 

For NOX substitution to yield an 

equivalent ozone decrease as required in 

section 182(c)(2)(C), we only need to 

know that reductions of NOX are at least 

as effective as reductions of VOC for 

reducing ozone concentrations. Further, 

the estimate that NOX emissions 

reductions are 13 times as effective as 

VOC reductions is quantitative, not 

qualitative. 

With respect to post-2015 emissions 

changes, we note that NOX and VOC 

emissions in Eastern Kern are projected 

to decrease slightly after 2015 through 

year 2021, largely due to reductions in 

mobile source emissions offsetting 

increases from stationary and area 

sources.52 In the upwind areas of SJV 

and SCAB, the same is true but NOX

emissions are projected to decrease at a 

faster rate than VOC emissions,53 which 

would have the effect of increasing the 

VOC:NOX ratio, making Eastern Kern 

even more NOX-limited. The emissions 

projections in the 2017 Eastern Kern 

Ozone SIP take into account long-term 

trends for the various source categories, 

including electricity generation. The 

commenter has not cited any particular 

natural-gas power plant closure that 

would affect the Eastern Kern area, and 

we are not aware of any such closure. 

The possible replacement of NOXproducing electricity generation by 

wind and solar power cited by the 

commenter would also tend to make the 

area more NOX-limited. The geographic 

distribution of the emissions changes is 

also not of concern. Emissions from the 

upwind areas are channeled through a 

small set of mountain passes regardless 

of their precise upwind location. 

Emissions within Eastern Kern itself are 

so much lower than those of the upwind 

areas that their particular location 

within the nonattainment area does not 

affect the NOX-limited conditions there. 

Because the VOC:NOX ratio of emissions 

input to the model increases between 

2012 and 2020, if additional modeling 

were carried out using 2020 emissions, 

it is expected that ozone formation 

would be even more NOX-limited.54

Thus neither the magnitude nor the 

geographic distribution for the post2015 emissions would change the EPA’s 

conclusion that the NOX substitution 

used for the RFP demonstration in the 

2017 Eastern Kern Ozone SIP meets the 

requirements of CAA section 

182(c)(2)(C). 

Lastly, we note that CAA section 

182(c)(2)(C), in contrast to CAA section 

182(c)(2)(A), does not explicitly 

prescribe the use of photochemical grid 

modeling or equivalent analytical 

method to demonstrate the equivalence 

of NOx emission reductions (relative to 

VOC emissions reductions) on ozone 

concentrations. The NOX equivalence 

demonstration for RFP purposes need 

not be based on the same analytical 

methods used in the attainment 

demonstration. Therefore, we are 

approving the RFP demonstration and 

its reliance on NOX substitution for a 

portion of the VOC emissions 

reductions otherwise required based on 

both qualitative and quantitative 

technical analyses. 

Comment #4: CBD asserts that the 

EPA fails to give notice of how the 

submittal addresses the demonstration 

required under CAA section 182(c)(2)(C) 

and thus the EPA’s proposal is not in 

accordance with procedure required by 

law. In particular, the commenter states 

that EPA has failed to give adequate 

notice of its proposed interpretation of 

section 182(c)(2)(C). The commenter 

observes that Table 3 of the proposed 

rule treats a percentage of NOX

reductions as equivalent to an equal 

percentage of VOC reductions, but 

asserts that the proposed rule does not 

explain why a percentage reduction in 

NOX emissions results in equivalent 

ozone reductions to an equal reduction 

in VOC emissions, as required by 

section 182(c)(2)(C). The commenter 

suggests that the proposed rule may 

have used the procedure recommended 

in a December 1993 guidance document 

from the EPA’s Office of Air Quality 

Planning and Standards entitled ‘‘NOX

Substitution Guidance.’’ The commenter 

argues that because the NOX

Substitution Guidance is non-binding, 

the notice must indicate whether the 

EPA intends to adopt the Guidance’s 

interpretation of the CAA, and that if 

the EPA instead believes that the 

Eastern Kern calculation is a legitimate 

demonstration for other reasons, it must 

re-propose the action. 

Response to Comment #4: The EPA 

disagrees with the commenter that the 

proposed rulemaking fails to give 

adequate notice regarding our proposed 

approval of the District’s use of NOX

substitution, or that we would be 

required to re-propose with additional 

justification prior to taking final action 

on this portion of the proposal. As 

described in responses to comments #2 

and #3 above, the modeling and analysis 

submitted to support the District’s 

control strategy and attainment 

demonstration highlight the need for 

significant NOX reductions in the 

upwind San Joaquin Valley and South 

Coast Air Basin for the Eastern Kern to 

attain the 2008 ozone NAAQS, and 

demonstrate that these NOX reductions 

will be more effective on a percentage 

basis than VOC reductions at reducing 

ozone concentrations in the 

nonattainment area. As described 

below, our proposal includes a 

summary and analysis of relevant 

portions of the SIP submittals, including 

NOX substitution in the RFP 

demonstration. 

Section III.C of the proposed 

rulemaking describes our proposed 

approval of the District’s RFP 


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55 85 FR 68268, 68274–68276. 

56 Id. at 68274–68276 (see footnotes 55 and 65). 

57 Id. at 68275–68276. 

58See NOX Substitution Guidance at 3 (noting 

that the EPA approves substitution proposals on a 

case-by-case basis, including any reasonable 

substitution proposal). 

59 40 CFR 93.101 (emphasis added). 

60 Id. (emphasis added). 

demonstration.55 This section describes 

the statutory and regulatory 

requirements for an RFP demonstration, 

including the option under CAA section 

182(c)(2)(C) to substitute NOX emissions 

reductions for VOC reductions, and the 

reasons for the EPA’s approval of this 

demonstration. The discussion includes 

citations to CAA section 182(c)(2)(C) 

and the implementing regulations for 

the 2008 ozone NAAQS, as well as 

relevant portions of the preamble to the 

2008 Ozone SRR that address the 

applicable requirements.56 The 

explanation that the District’s RFP 

demonstration substitutes NOX

reductions for VOC reductions in the 

RFP demonstration, including the 

District’s substitution of NOX reductions 

for VOC reductions on a percentage 

basis, is summarized in Table 3 of the 

proposal.57

As the commenter notes, the proposed 

rulemaking does not include a specific 

justification in support of the District’s 

use of NOX substitution on a percentage 

basis. The discussion and tables in 

section III.C of our proposal document 

the need for additional NOX reductions 

exceeding the necessary additional VOC 

reductions. As discussed in Response to 

Comment #2, the EPA finds that the 

2017 Eastern Kern Ozone SIP and 

additional technical documentation 

provide sufficient evidence that NOX

emissions reductions are more effective 

than VOC reductions on a percentage 

basis. This conclusion was based on an 

analysis of ambient data, pollution 

transport patterns, the magnitude of 

upwind area emissions, and basic 

scientific knowledge about the 

VOC:NOX ratios downwind of large 

urban areas. As addressed above, given 

this need for NOX reductions and the 

modeled anticipated impact on Eastern 

Kern, substituting NOX for VOC on a 

percentage-reduction basis represents a 

conservative approach that will result in 

equivalent or greater reductions in 

ozone concentrations than would result 

through the VOC-only reductions 

required under CAA section 

182(c)(2)(B). 

As the commenter notes, this 

approach is consistent with the 

procedures outlined in the EPA’s 1993 

NOX Substitution Guidance. However, 

as the commenter also notes, the NOX

Substitution Guidance is non-binding, 

and the EPA must ensure that any use 

of NOX substitution is reasonable in 

light of local conditions and needs.58 In 

this case, our approval is supported by 

the NOX reductions being more effective 

than VOC in the area, and the need for 

NOX reductions as set out in the control 

strategies for the upwind SJV and SCAB. 

For this reason, we find that the 

proposed rulemaking and associated 

supporting documents included in the 

docket for that action provide sufficient 

documentation that the NOX

substitution used in the District’s RFP 

demonstration is consistent with CAA 

section 182(c)(2)(C), and we disagree 

that the EPA would be required to repropose with additional analysis or 

justification. 

Comment #5: CBD provides numerous 

comments directed at the EPA’s NOX

Substitution Guidance, contending that 

if the EPA intended to adopt the 

positions set forth in the NOX

Substitution Guidance, the proposal 

would be arbitrary and capricious and 

contrary to law because of problems 

with the NOX Substitution Guidance. 

These comments assert generally that 

the NOX Substitution Guidance 

contradicts CAA section 182(c)(2)(C) by 

recommending a procedure that fails to 

demonstrate any equivalence between 

VOC and NOX reductions, relies on 

incorrect policy assumptions, and gives 

legal justifications that are without 

merit. 

Response to Comment #5: Comments 

relating solely to the NOX Substitution 

Guidance are outside the scope of this 

rulemaking action. As noted in our 

Response to Comment #4 above, our 

approval of the District’s use of NOX

substitution is supported by local 

conditions and needs as documented in 

the modeling and analysis included in 

the 2017 Eastern Kern Ozone SIP, and 

is consistent with the requirements in 

CAA section 182(c)(2)(C). 

Comment #6: CBD asserts that, 

because the EPA must disapprove the 

submitted RFP demonstration, the EPA 

cannot determine that the motor vehicle 

emission budgets (MVEBs) are allowable 

as a portion of the total allowable 

emissions to meet RFP, and with no 

measure of total allowable emissions for 

RFP, there is no basis for approval of the 

MVEBs. 

Response to Comment #6: As 

discussed in responses to comments #1 

through #4, the EPA concludes that the 

RFP demonstration can be approved 

independently of the attainment 

demonstration and that the substitution 

of NOX emissions reductions for VOC 

emissions reductions in the RFP 

demonstration is adequately supported. 

In this final rule, on the basis of the 

rationale presented in the proposed rule 

and in our responses to comments, we 

are taking final action to approve the 

RFP demonstration and related MVEBs. 

Comment #7: CBD contends that the 

MVEBs must be consistent with 

attainment requirements as well as RFP 

requirements, and in the absence of an 

approved attainment demonstration and 

control strategy, the RFP MVEBs must 

be disapproved. In support of this 

contention, CBD cites selected portions 

of CAA section 176(c) and the EPA’s 

transportation conformity rule. First, 

under section 176(c)(1)(B)(iii), CBD 

notes that a Federal action cannot 

‘‘delay timely attainment of any 

standard,’’ and without an approved 

attainment demonstration and control 

strategy, which could require VOC and 

NOX emissions reductions beyond those 

required by section 182(c)(2)(C), there is 

no way to tell if a transportation plan, 

improvement program, or project will 

‘‘delay timely attainment’’ of the 2008 

ozone standards, even if it stays within 

the proposed MVEBs. 

Second, CBD notes that, under the 

EPA’s rules for transportation 

conformity, the term ‘‘control strategy 

implementation plan revision’’ is 

defined as the ‘‘implementation plan 

which contains specific strategies for 

controlling the emissions of and 

reducing ambient levels of pollutants in 

order to satisfy CAA requirements for 

demonstrations of reasonable further 

progress and attainment.’’ 59 For 

attainment plans (as opposed to 

maintenance plans), MVEBs are in part 

defined as ‘‘that portion of the total 

allowable emissions defined in the 

submitted or approved control strategy 

implementation plan revision.’’ 60 Thus, 

CBD argues that the MVEBs depend on 

the control strategy implementation 

plan revision, which must demonstrate 

both RFP and attainment. 

In addition, CBD notes that the 

particular MVEBs proposed for approval 

are derived from the projected on-road 

mobile source emissions estimates in 

the attainment year (2020) emissions 

inventory upon which the attainment 

demonstration is based, and thus must 

be consistent with attainment 

requirements as well as RFP 

requirements. Because the EPA has not 

approved the attainment demonstration, 

including the projected attainment year 

emissions inventory, CBD argues that 

the EPA cannot approve the MVEBs that 

derive from that inventory. 

Response to Comment #7: First, we 

acknowledge that the MVEBs are 

derived from the projected attainment 


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61 40 CFR 93.101 (emphasis added). 

62 40 CFR 93.118(e)(4)(iv) (emphases added). 

63The commenter claims that the EPA’s adequacy 

determination is irrelevant for purposes of whether 

the EPA can approve the MVEBs, because the EPA 

has stated that its adequacy review ‘‘should not be 

used to prejudge EPA’s ultimate approval or 

disapproval of the SIP.’’ The EPA agrees that the 

adequacy determination is based on a cursory 

review of the SIP submittal when it is made prior 

to action on the SIP submittal itself. However, 

today’s adequacy determination is based on the 

EPA’s complete review, and approval, of the RFP 

demonstration in the 2017 Eastern Kern Ozone SIP. 

64Natural Resources Defense Council v. EPA, 638 

F.3d 1183, 1191 (9th Cir. 2011). 

65 Id. 

66As noted previously, we are deferring action on 

the attainment demonstration and reasonably 

available control measures demonstration elements 

of the 2017 Eastern Kern Ozone SIP at this time. 

67Regarding the Serious nonattainment area 

requirements for new source review (NSR) and for 

implementation of reasonably available control 

technology (RACT) for the 2008 ozone NAAQS in 

Eastern Kern, we will be taking action as necessary 

on district rules addressing the NSR and RACT 

requirements in separate rulemakings and will 

evaluate compliance with the applicable Serious 

area nonattainment requirements at that time. 

68Pursuant to 40 CFR 93.118(f)(2)(iii), the EPA’s 

adequacy determination is effective upon 

publication of this final rule in the Federal 

Register. Upon the effective date of the adequacy 

determination, the 2020 budgets from the in the 

2020 Conformity Budget Update will replace the 

budgets that were previously found adequate for 

use in transportation conformity determinations 

(i.e., the 2008 budgets from the ‘‘Eastern Kern 

County 2008 8-hour Ozone Early Progress Plan.’’ 

year (2020) emissions inventory. 

However, year 2020 is both an RFP 

milestone year and the attainment year 

for the Eastern Kern Serious ozone 

nonattainment area. Therefore, the 

projected 2020 emissions inventory is 

the basis for both the RFP 

demonstration for that milestone year 

and for the attainment demonstration. 

As explained in Response to Comment 

#1, the RFP demonstration and 

attainment demonstration requirements 

are independent requirements under the 

SRR and, thus, can be approved 

separately. In this final action, we are 

approving the MVEBs only for RFP 

purposes and not for attainment 

purposes. 

Second, we note that CAA section 

176(c)(4)(B) obligates the EPA to 

promulgate, and periodically update, 

criteria and procedures for 

demonstrating and assuring conformity 

in the case of transportation plans, 

programs, and projects, and we have 

done so at 40 CFR part 93, subpart A 

(‘‘Conformity to State or Federal 

Implementation Plans of Transportation 

Plans, Programs, and Projects 

Developed, Funded or Approved Under 

Title 23 U.S.C. or the Federal Transit 

Laws’’) (herein, ‘‘transportation 

conformity rule’’). 

Our transportation conformity rule 

defines ‘‘motor vehicle emissions 

budget’’ as that portion of the total 

allowable emissions defined in the 

submitted or approved control strategy 

implementation plan revision or 

maintenance plan for a certain date for 

the purpose of meeting reasonable 

further progress milestones or 

demonstrating attainment or 

maintenance of the NAAQS. . . .’’ 61

Further, among the criteria we must use 

when evaluating a MVEB for adequacy 

or approval is the criterion at 40 CFR 

93.118(e)(4)(iv) which requires MVEBs, 

when considered together with all other 

emissions sources, to be consistent with 

applicable requirements for reasonable 

further progress, attainment, or 

maintenance (whichever is relevant to 

the given implementation plan 

submission).62

Thus, under our transportation 

conformity rule, the EPA can approve 

MVEBs if we find them consistent, 

when considered together with all other 

emissions sources, with the applicable 

requirements for RFP or attainment; it is 

not required that the MVEBs be 

consistent with RFP and attainment but 

only that they are consistent with the 

requirement that is relevant for 

purposes of the SIP. In this instance, 

while the MVEBs for year 2020 are 

numerically the same for both RFP and 

attainment, the relevant requirements 

are those for RFP, not attainment, and 

we are approving the MVEBs as 

consistent with those requirements, not 

the attainment requirements, consistent 

with the transportation conformity 

rule.63 This interpretation has been 

upheld by the Ninth Circuit in Natural 

Resources Defense Council v. EPA, 638 

F.3d 1183 (9th Cir. 2011). In Natural 

Resources Defense Council, the 

petitioners similarly argued that the 

Clean Air Act and the EPA’s 

implementing regulations require the 

EPA to consider attainment data when 

determining the adequacy of budgets for 

milestone years,64 but the Ninth Circuit 

agreed with the EPA that the EPA’s 

transportation conformity rule provides 

otherwise. More specifically, the court 

agreed with the EPA that, for a 

milestone year, a budget need only 

demonstrate reasonable further progress 

toward the ultimate goal of 

attainment.65

In light of our responses to the 

comments and for the reasons given in 

the proposed rule, we are taking final 

action to approve the RFP 

demonstration and the related MVEBs 

and are taking final action to find the 

MVEBs adequate for transportation 

conformity purposes. 

III. Final Action 

For the reasons discussed in detail in 

the proposed rule and summarized 

herein, under CAA section 110(k)(3), the 

EPA is taking final action to approve as 

a revision to the California SIP the 

following portions of the Eastern Kern 

2017 Ozone Plan submitted by CARB on 

October 25, 2017, the 2018 SIP Update 

submitted on December 5, 2018, and the 

2020 Conformity Budget Update 

submitted on August 31, 2020, that 

together comprise the 2017 Eastern Kern 

Ozone SIP: 66

• Base year emissions inventory 

element in the Eastern Kern 2017 Ozone 

Plan as meeting the requirements of 

CAA sections 172(c)(3) and 182(a)(1) 

and 40 CFR 51.1115 for the 2008 ozone 

NAAQS; 

• Emissions statement element in the 

Eastern Kern 2017 Ozone Plan as 

meeting the requirements of CAA 

section 182(a)(3)(B) and 40 CFR 51.1102 

for the 2008 ozone NAAQS; 

• ROP demonstration element in the 

Eastern Kern 2017 Ozone Plan as 

meeting the requirements of CAA 

182(b)(1) and 40 CFR 51.1110(a)(2) for 

the 2008 ozone NAAQS; 

• RFP demonstration element in the 

2018 SIP Update as meeting the 

requirements of CAA sections 172(c)(2) 

and 182(c)(2)(B), and 40 CFR 

51.1110(a)(2)(ii) for the 2008 ozone 

NAAQS; 

• Motor vehicle emissions budgets in 

the 2020 Conformity Budget Update for 

the 2020 RFP milestone year, as shown 

below, because they are consistent with 

the RFP demonstration for the 2008 

ozone NAAQS finalized for approval 

herein and meet the other criteria in 40 

CFR 93.118(e); 

TRANSPORTATION CONFORMITY BUDGETS FOR THE 2008 OZONE NAAQS 

IN EASTERN KERN

[Summer planning inventory, tpd] 

Budget year VOC NOX

2020 .................. 1.3 3.6 

We are also taking final action to find 

that: 

• The enhanced monitoring 

requirements of CAA section 182(c)(1) 

and 40 CFR 51.1102 are being met in 

Eastern Kern for the 2008 ozone 

NAAQS; 67 and 

• The submitted 2020 budgets 

included in the 2020 Conformity Budget 

Update are adequate for transportation 

conformity purposes.68

Lastly, we are approving 

conditionally, under CAA section 

110(k)(4), the contingency measure 


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69Letter dated September 1, 2020, from Glen E. 

Stephens, Air Pollution Control Officer, EKAPCD, 

to Richard Corey, Executive Officer, CARB; and 

letter dated September 18, 2020, from Richard W. 

Corey, Executive Officer, CARB, to John Busterud, 

Regional Administrator, EPA Region IX. 

element of the 2017 Eastern Kern Ozone 

SIP as meeting the requirements of CAA 

sections 172(c)(9) and 182(c)(9) for RFP 

and attainment contingency measures. 

Our approval is based on commitments 

by the District and CARB to supplement 

the element through submission, as a 

SIP revision (within one year of our 

final conditional approval action), of a 

revised District rule or rules that would 

add new limits or other requirements if 

an RFP milestone is not met or if 

Eastern Kern fails to attain the 2008 

ozone NAAQS by the applicable 

attainment date.69

IV. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

federal regulations. 42 U.S.C. 7410(k); 

40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, the EPA’s role is to 

approve state choices, provided that 

they meet the criteria of the Clean Air 

Act. Accordingly, this action merely 

approves or conditionally approves state 

plans as meeting federal requirements 

and does not impose additional 

requirements beyond those imposed by 

state law. For that reason, this action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Orders 12866 (58 FR 51735, 

October 4, 1993) and 13563 (76 FR 3821, 

January 21, 2011); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide the EPA with the 

discretionary authority to address 

disproportionate human health or 

environmental effects with practical, 

appropriate, and legally permissible 

methods under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, the SIP is not approved 

to apply on any Indian reservation land 

or in any other area where the EPA or 

an Indian tribe has demonstrated that a 

tribe has jurisdiction. In those areas of 

Indian country, the rule does not have 

tribal implications and will not impose 

substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. The EPA will 

submit a report containing this action 

and other required information to the 

U.S. Senate, the U.S. House of 

Representatives, and the Comptroller 

General of the United States prior to 

publication of the rule in the Federal 

Register. A major rule cannot take effect 

until 60 days after it is published in the 

Federal Register. This action is not a 

‘‘major rule’’ as defined by 5 U.S.C. 

804(2). 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by August 24, 2021. 

Filing a petition for reconsideration by 

the Administrator of this final rule does 

not affect the finality of this action for 

the purposes of judicial review nor does 

it extend the time within which a 

petition for judicial review may be filed, 

and shall not postpone the effectiveness 

of such rule or action. This action may 

not be challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2)). 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Nitrogen dioxide, Ozone, Reporting and 

recordkeeping requirements, Volatile 

organic compounds. 

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

Dated: June 16, 2021. 

Deborah Jordan, 

Acting Regional Administrator, Region IX. 

For the reasons stated in the 

preamble, the EPA amends Part 52, 

chapter I, title 40 of the Code of Federal 

Regulations as follows: 

PART 52—APPROVAL AND 

PROMULGATION OF 

IMPLEMENTATION PLANS 

■ 1. The authority citation for part 52 

continues to read as follows: 

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

Subpart F—California 

■ 2. Section 52.220 is amended by 

reserving paragraphs (c)(556), (557), 

(558), and (559), and adding paragraphs 

(c)(514)(ii)(A)(8), (c)(560) and (c)(561) to 

read as follows: 

§ 52.220 Identification of plan—in part. 

* * * * * 

(c) * * * 

(514) * * * 

(ii) * * * 

(A) * * * 

(8) 2018 Updates to the California 

State Implementation Plan, adopted on 

October 25, 2018, chapter IV (‘‘SIP 

Elements for Eastern Kern County’’); 

and pages A–11 through A–14 of 

appendix A (‘‘Nonattainment Area 

Inventories’’), only. 

* * * * * 

(560) The following plan was 

submitted on October 25, 2017 by the 

Governor’s designee. 

(i) [Reserved] 

(ii) Additional materials. 

(A) Eastern Kern Air Pollution Control 

District. 

(1) 2017 Ozone Attainment Plan For 

2008 Federal 75 ppb 8-Hour Ozone 

Standard, adopted on July 27, 2017, 

excluding chapter XI (‘‘Reasonably 

Available Control Measures 

Demonstration’’) and chapter XIII 

(‘‘Attainment Demonstration’’). 

(2) [Reserved] 

(B) [Reserved] 

(561) The following plan was 

submitted on August 31, 2020 by the 

Governor’s designee as an attachment to 

a letter dated August 25, 2020. 

(i) [Reserved] 

(ii) Additional materials. 

(A) California Air Resources Board. 

(1) Transportation Conformity Budget 

State Implementation Plan Update for 


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1 86 FR 10524. 

2 82 FR 30770. 

3The 2017 final rule stated incorrectly that the 

criteria in 40 CFR 51.166(r)(1) had not been met. 

Our proposal notice (81 FR 95074, December 27, 

2016) and Technical Support Document (TSD) 

correctly noted that only the criteria in 40 CFR 

41.166(r)(2) had not been met. See e.g., Section 4.2, 

number 15 on Page 18 of the TSD for the 2017 final 

action. 

the Eastern Kern 2017 Ozone 

Attainment Plan, release date: June 19, 

2020. 

(2) [Reserved] 

(B) [Reserved] 

* * * * * 

■ 3. Section 52.248 is amended by 

adding paragraph (m) to read as follows: 

§ 52.248 Identification of plan—conditional 

approval. 

* * * * * 

(m) The EPA is conditionally 

approving the California State 

Implementation Plan (SIP) for Eastern 

Kern for the 2008 ozone NAAQS with 

respect to the contingency measures 

requirements of CAA sections 172(c)(9) 

and 182(c)(9). The conditional approval 

is based on a commitment from the 

Eastern Kern Air Pollution Control 

District (District) in a letter dated 

September 1, 2020, to adopt a specific 

rule revision or revisions, and a 

commitment from the California Air 

Resources Board (CARB) dated 

September 18, 2020, to submit the 

amended District rule or rules to the 

EPA within 12 months of the final 

conditional approval. If the District or 

CARB fail to meet their commitments 

within one year of the final conditional 

approval, the conditional approval is 

treated as a disapproval. 

[FR Doc. 2021–13608 Filed 6–24–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R09–OAR–2020–0519; FRL–10024– 

19–Region 9] 

Air Quality Implementation Plan; 

California; Mendocino County Air 

Quality Management District; 

Stationary Source Permits 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is taking final action to 

approve revisions to the Mendocino 

County Air Quality Managment District 

(MCAQMD or ‘‘District’’) portion of the 

California State Implementation Plan 

(SIP). These revisions concern the 

District’s prevention of significant 

deterioration (PSD) permitting program 

for new and modified stationary sources 

of air pollution. We are approving these 

local rules pursuant to requirements 

under part C of title I of the Clean Air 

Act as amended in 1990 (CAA or the 

‘‘Act’’). 

DATES: This rule will be effective on July 

26, 2021. 

ADDRESSES: The EPA has established a 

docket for this action under Docket No. 

EPA–R09–OAR–2020–0519. All 

documents in the docket are listed on 

the https://www.regulations.gov 

website. Although listed in the index, 

some information is not publicly 

available, e.g., Confidential Business 

Information (CBI) or other information 

the disclosure of which is restricted by 

statute. Certain other material, such as 

copyrighted material, is not placed on 

the internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available through https:// 

www.regulations.gov, or please contact 

the person identified in the FOR FURTHER

INFORMATION CONTACT section for 

additional availability information. 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: 

Amber Batchelder, EPA Region IX, 75 

Hawthorne St., San Francisco, CA 

94105; by phone: (415) 947–4174, or by 

email to batchelder.amber@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document, the terms 

‘‘we,’’ ‘‘us’’ and ‘‘our’’ refer to the EPA. 

Table of Contents 

I. Proposed Action 

II. Public Comments and EPA Responses 

III. EPA Action 

IV. Incorporation by Reference 

V. Statutory and Executive Order Reviews 

I. Proposed Action 

On February 22, 2021, the EPA 

proposed to approve the following rules 

into the MCAQMD portion of the 

California SIP.1

TABLE 1—SUBMITTED RULES

Rule No. Rule title Amended Submitted 

1–220 ................ New Source Review Standards (Including PSD Evaluations) ................................................. 4/7/2020 8/10/2020 

1–230 ................ Action on Applications .............................................................................................................. 4/7/2020 8/10/2020 

The EPA previously finalized a 

limited approval and limited 

disapproval of Rule 1–220 on July 3, 

2017.2 We listed the following two 

deficiencies in our final limited 

approval and limited disapproval of 

Rule 1–220: 

• Rule 1–220 does not contain any 

provisions specifying that required air 

quality modeling shall be based on the 

applicable models, databases, and other 

requirements specified in part 51 

Appendix W; therefore, the 

requirements of 40 CFR 51.160(f) and 

51.166(l) have not been met. 

• The requirements of 40 CFR 

51.166(r)(2) 3 have not been met because 

the rule does not include the necessary 

information about a source’s obligations. 

The District resolved the first 

deficiency by adding the required air 

quality modeling provisions to Rule 

1–220 and addressed the second 

deficiency by revising Rule 1–230 to 

include information about a source’s 

obligations under the CAA. We have 

determined that the amended sections 

of these rules satisfy the statutory and 

regulatory requirements for a PSD 

program as set forth in the applicable 

provisions of part C of title I of the Act 

and in 40 CFR 51.160–51.164 and 

51.166. 

Our proposed action contains more 

information on the rules and our 

evaluation. 

II. Public Comments and EPA 

Responses 

The EPA’s proposed action provided 

a 30-day public comment period. During 

this period, we received one comment, 

which is included in the docket for this 

action. We do not consider this 

comment to be germane or relevant to 


lotter on DSK11XQN23PROD with RULES1