Federal Register / Vol. 86, No. 114 / Wednesday, June 16, 2021 / Rules and Regulations 31927 

IV. Statutory and Executive Order 

Reviews 

Under the CAA, the Administrator is 

required to approve a SIP submission 

that complies with the provisions of the 

CAA and applicable Federal regulations. 

42 U.S.C. 7410(k); 40 CFR 52.02(a). 

Thus, in reviewing SIP submissions, 

EPA’s role is to approve state choices, 

provided that they meet the criteria of 

the CAA. Accordingly, this action 

merely approves state law 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 CAA; and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable 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 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 16, 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, 

Lead, Reporting and recordkeeping 

requirements. 

Dated: June 9, 2021. 

Cheryl Newton, 

Acting Regional Administrator, Region 5. 

For the reasons stated in the 

preamble, EPA amends title 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. 

§ 52.1870 [Amended] 

■ 2. In § 52.1870, the table in paragraph 

(c) is amended by removing the heading 

‘‘Chapter 3745–71 Lead Emissions’’ and 

the entries for ‘‘3745–71–01’’, ‘‘3745– 

71–03’’, ‘‘3745–71–05’’, and ‘‘3745–71– 

06’’. 

[FR Doc. 2021–12554 Filed 6–15–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R09–OAR–2020–0589; FRL–10024– 

21–Region 9] 

Air Plan Approval; Arizona; Stationary 

Sources; New Source Review Updates 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is taking final action to 

approve revisions to the Arizona 

Department of Environmental Quality’s 

(ADEQ) portion of the Arizona State 

Implementation Plan (SIP) that were 

submitted to the EPA by the ADEQ. 

These revisions concern the ADEQ’s 

SIP-approved rules for the issuance of 

New Source Review (NSR) permits for 

stationary sources under the Clean Air 

Act (CAA or Act). This action updates 

the ADEQ’s NSR rules in the Arizona 

SIP and corrects the remaining 

deficiencies in the ADEQ’s NSR 

program that we identified as the basis 

for our limited disapprovals in final 

rulemaking actions in 2015 and 2016. 

Additionally, we are finding that the 

ADEQ’s SIP-approved NSR permitting 

program meets requirements for 

visibility protection for major stationary 

sources under the Act and are removing 

the Federal Implementation Plans (FIPs) 

for the ADEQ related to these visibility 

protection requirements. 

DATES: This rule is effective on July 16, 

2021. 

ADDRESSES: The EPA has established a 

docket for this action under Docket ID 

No. EPA–R09–OAR–2020–0589. 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 


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1 80 FR 67319 (Nov. 2, 2015). 

2 In the 2015 NSR action, we also finalized other 

actions, including a partial disapproval related to 

the fine particulate matter (PM2.5) significant 

monitoring concentration, and limited approvals, 

without corresponding limited disapprovals, related 

to section 189(e) of the Act. 

3 83 FR 19631 (May 4, 2018). 

4 81 FR 40525 (June 22, 2016). 

5 83 FR 19631, 19634. The conditional approval 

was based upon a December 6, 2017 letter from the 

State committing to submit a SIP revision to the 

EPA consisting of rule revisions and/or 

demonstrations that would correct the deficiencies 

related to ammonia as a precursor to PM2.5 under 

the NNSR program requirements in CAA section 

189(e). See 83 FR 19631, 19633–19634. 

6Concurrent with our proposed conditional 

approval action in 2018, we made an interim final 

determination that the State of Arizona had 

satisfied the requirements of part D of the CAA 

permitting program for areas under the jurisdiction 

of ADEQ with respect to PM2.5 precursors under 

section 189(e). See 83 FR 1195 (January 10, 2018) 

and 83 FR 1212 (January 10, 2018). The effect of our 

interim final determination was that the imposition 

of sanctions that had been triggered were deferred. 

7See 83 FR 19631, 19633–19634. 

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: Lisa 

Beckham, EPA Region IX, 75 Hawthorne 

St., San Francisco, CA 94105. By phone: 

(415) 972–3811 or by email at 

beckham.lisa@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document, ‘‘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 

Definitions 

For this document, we are giving 

meaning to certain words or initials as 

follows: 

(i) The words or initials Act or CAA 

mean or refer to the Clean Air Act, 

unless the context indicates otherwise. 

(ii) The initials ADEQ mean or refer 

to the Arizona Department of 

Environmental Quality. 

(iii) The initials Ag BMP mean or refer 

to the State of Arizona’s Agricultural 

Best Management Practices program. 

(iv) The initials ARS mean or refer to 

the Arizona Revised Statutes. 

(v) The initials CBI mean or refer to 

confidential business information. 

(vi) The initials CFR mean or refer to 

the Code of Federal Regulations. 

(vii) The initials CO mean or refer to 

carbon monoxide. 

(viii) The words EPA, we, us or our 

mean or refer to the United States 

Environmental Protection Agency. 

(ix) The initials FIP mean or refer to 

Federal Implementation Plan. 

(x) The initials MMBtu/hr mean or 

refer to million British thermal units per 

hour. 

(xi) The initials NAAQS mean or refer 

to the National Ambient Air Quality 

Standards. 

(xii) The initials NESHAP mean or 

refer to the National Emission Standards 

for Hazardous Air Pollutants. 

(xiii) The initials NNSR mean or refer 

to Nonattainment New Source Review. 

(xiv) The initials NOX mean or refer to 

oxides of nitrogen. 

(xv) The initials NSPS mean or refer 

to New Source Performance Standards. 

(xvi) The initials NSR mean or refer 

to New Source Review. 

(xvii) The initials PM2.5 mean or refer 

to particulate matter with an 

aerodynamic diameter of less than or 

equal to 2.5 micrometers, or fine 

particulate matter. 

(xviii) The initials PM10 mean or refer 

to particulate matter with an 

aerodynamic diameter of less than or 

equal to 10 micrometers. 

(xix) The initials PSD mean or refer to 

Prevention of Significant Deterioration. 

(xx) The initials SER mean or refer to 

significant emission rate. 

(xxi) The initials SIP mean or refer to 

State Implementation Plan. 

(xxii) The initials SO2 mean or refer 

to sulfur dioxide. 

(xxiii) The words State or Arizona 

mean the State of Arizona, unless the 

context indicates otherwise. 

(xxiv) The initials TSD mean or refer 

to the technical support document for 

this action unless the context indicates 

otherwise. 

I. Proposed Action 

On December 23, 2020 (85 FR 83868), 

the EPA proposed to approve revisions 

to the ADEQ portion of the Arizona SIP 

consisting of several rule revisions and 

demonstrations submitted by the ADEQ 

related to the ADEQ’s CAA NSR 

permitting program. 

First, we proposed to approve a July 

22, 2020 SIP submittal from the ADEQ 

that contains rule revisions and other 

demonstrations primarily intended to 

correct deficiencies in the ADEQ’s 

minor NSR program (referred to 

hereinafter as the ‘‘2020 Minor NSR 

submittal’’). The deficiencies being 

corrected by the 2020 Minor NSR 

submittal were identified in a November 

2, 2015 1 final limited approval and 

limited disapproval action by the EPA 

(referred to hereinafter as the EPA’s 

‘‘2015 NSR action’’).2 Our 2015 NSR 

action was the result of an extensive 

review of the ADEQ’s NSR program, in 

response to a comprehensive NSR 

program update submitted by the ADEQ 

to the EPA in a 2012 SIP revision 

(referred to hereinafter as the ‘‘2012 

NSR SIP submittal’’). The 2012 NSR SIP 

submittal represented the ADEQ’s first 

comprehensive update to its SIPapproved NSR program since the 1980s. 

Our review of the 2012 NSR SIP 

submittal for compliance with CAA 

requirements therefore included all 

aspects of the ADEQ’s minor NSR, 

Prevention of Significant Deterioration 

(PSD), and nonattainment NSR (NNSR) 

permitting programs, including NSRrelated visibility requirements for major 

stationary sources. In a May 4, 2018 

final rule,3 we approved revisions to the 

ADEQ’s NSR program, submitted to the 

EPA in 2017, that corrected a large 

portion of the deficiencies identified in 

our 2015 NSR action, primarily related 

to the PSD and NNSR programs 

(referred to hereinafter as the ‘‘2018 

Major NSR action’’). Thus, the 2020 

Minor NSR submittal that is the subject 

of our present action addresses the 

remaining deficiencies from our 2015 

NSR action. 

Second, our December 23, 2020 

proposed action also included our 

proposed approval of a March 29, 2019 

SIP submittal, and a January 14, 2020 

supplemental submittal, from the 

ADEQ. These two submittals are 

intended to resolve an ADEQ NNSR 

program deficiency related to the 

permitting of ammonia as a precursor to 

PM2.5 in the West Central Pinal and 

Nogales PM2.5 nonattainment areas (the 

March 29, 2019 submittal and January 

14, 2020 supplement are collectively 

referred to hereinafter as the ‘‘Ammonia 

PM2.5 NSR submittal’’). In a June 22, 

2016 4 final limited disapproval rule 

action, we had identified additional 

deficiencies in the ADEQ’s NNSR 

program related to PM2.5 precursors 

(referred to hereinafter as the EPA’s 

‘‘2016 PM2.5 precursor action’’). In our 

2018 Major NSR action, in addition to 

approving rule revisions to the ADEQ’s 

NSR program, the EPA conditionally 

approved 5 the ADEQ’s NNSR program 

pursuant to CAA section 110(k)(4) 

solely with respect to ammonia as a 

precursor to PM2.5 under section 189(e) 

of the Act.6 We found in our 2018 Major 

NSR action that the ADEQ’s SIP 

revisions otherwise resolved the 

deficiencies identified in our 2016 PM2.5

precursor action.7 In addition to 

resolving the deficiency that was the 

basis for our conditional approval for 

ammonia as a precursor to PM2.5 under 

CAA section 189(e), the Ammonia PM2.5

NSR submittal also includes other 


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8The ADEQ’s January 14, 2020 submittal 

requested that specific paragraphs from certain 

revised rules be added to the Arizona SIP. The 2020 

Minor NSR submittal clarified that the ADEQ 

requests that the entirety of each revised rule (with 

one exception) be included in the SIP, rather than 

only the selected paragraphs identified in the 

earlier submittal. 

9The visibility FIPs are implemented at 40 CFR 

52.27 for attainment areas and 40 CFR 52.28 for 

nonattainment areas. 

10One older rule provision that we are removing 

from the Arizona SIP, listed in Table 2, was from 

the Arizona Administrative Code, Title 9, Chapter 

3, Article 2. 

11This rule contains a new provision stating that 

a particular revised subsection, R18–2–101(131)(f), 

will take effect on the effective date of the EPA 

Administrator’s action approving it as part of the 

Arizona SIP. Therefore, the revised version of R18– 

2–101(131)(f) would become effective on the 

effective date of our approval of the current 

submittal of R18–2–101. 

minor and technical rule revisions to 

the ADEQ’s NSR program that we 

proposed to approve in our December 

23, 2020 proposed action.8

Finally, our December 23, 2020 

proposal also included our proposed 

determination that the ADEQ’s SIPapproved NSR program meets the 

visibility requirements for major NSR 

programs in 40 CFR 51.307. 

Accordingly, we proposed to update 40 

CFR 52.145(b) to remove the existing 

visibility FIPs 9 for those stationary 

sources subject to the ADEQ’s 

permitting jurisdiction. 

The EPA’s proposal and technical 

support document (TSD) for this 

rulemaking action have more 

information about the content of the 

ADEQ’s SIP submittals (collectively 

referred to hereinafter as the ‘‘2019–20 

NSR submittals’’), the deficiencies in 

the ADEQ’s NSR program that are being 

corrected, and our rationale for 

proposing approval. 

The rules that the EPA proposed to 

approve into the ADEQ’s portion of the 

Arizona SIP are listed in Table 1 of this 

notice, and the existing SIP-approved 

rules that we proposed to remove or 

supersede from the SIP are listed in 

Table 2 of this notice. The rules are from 

the Arizona Administrative Code, Title 

18—Environmental Quality, Chapter 2— 

Department of Environmental Quality— 

Air Pollution Control, Articles 1, 3, and 

4.10 These rules apply to all areas and 

stationary sources in Arizona for which 

the ADEQ has permitting jurisdiction. 

The ADEQ has permitting jurisdiction 

for the following stationary source 

categories in all areas of Arizona: 

Smelting of metal ores, coal-fired 

electric generating stations, petroleum 

refineries, Portland cement plants, and 

portable sources. The ADEQ also has 

permitting jurisdiction for major and 

minor sources in the following counties: 

Apache, Cochise, Coconino, Gila, 

Graham, Greenlee, La Paz, Mohave, 

Navajo, Santa Cruz, Yavapai, and Yuma. 

Finally, the ADEQ has permitting 

jurisdiction over major sources in Pinal 

County (currently delegated to Pinal 

County Air Quality Control District) and 

any source in Maricopa, Pima, or Pinal 

County for which the ADEQ asserts 

jurisdiction. 

TABLE 1—SUBMITTED RULES

Rule Title 

State 

effective 

date 

R18–2–101, except (20) ........ Definitions ........................................................................................................................................ 11 2/1/2020 

R18–2–301 ............................. Definitions ........................................................................................................................................ 2/1/2020 

R18–2–302 ............................. Applicability; Registration; Classes of Permits ............................................................................... 3/21/2017 

R18–2–302.01 ........................ Source Registration Requirements ................................................................................................. 2/1/2020 

R18–2–304 ............................. Permit Application Processing Procedures ..................................................................................... 2/1/2020 

R18–2–306 ............................. Permit Contents .............................................................................................................................. 3/21/2017 

R18–2–306.01 ........................ Permits Containing Voluntarily Accepted Emission Limitations and Standards ............................. 3/21/2017 

R18–2–317 ............................. Facility Changes Allowed Without Permit Revisions—Class I ....................................................... 8/7/2012 

R18–2–317.01 ........................ Facility Changes that Require a Permit Revision—Class II ........................................................... 8/7/2012 

R18–2–317.02 ........................ Procedures for Certain Changes that Do Not Require a Permit Revision—Class II ..................... 8/7/2012 

R18–2–319 ............................. Minor Permit Revisions ................................................................................................................... 3/21/2017 

R18–2–320 ............................. Significant Permit Revisions ........................................................................................................... 3/21/2017 

R18–2–334 ............................. Minor New Source Review ............................................................................................................. 2/1/2020 

R18–2–406 ............................. Permit Requirements for Sources Located in Attainment and Unclassifiable Areas ..................... 2/1/2020 

TABLE 2—RULES TO BE REMOVED OR SUPERSEDED

Rule Title EPA approval date 

Federal 

Register 

citation 

R18–2–101 ............................. Definitions .................................................................................. May 4, 2018 ............................ 83 FR 19631 

R18–2–301 ............................. Definitions .................................................................................. November 2, 2015 .................. 80 FR 67319 

R18–2–302 ............................. Applicability; Registration; Classes of Permits ......................... November 2, 2015 .................. 80 FR 67319 

R18–2–302.01 ........................ Source Registration Requirements ........................................... November 2, 2015 .................. 80 FR 67319 

R18–2–304 ............................. Permit Application Processing Procedures ............................... November 2, 2015 .................. 80 FR 67319 

R18–2–306 ............................. Permit Contents ........................................................................ November 2, 2015 .................. 80 FR 67319 

R18–2–306.01 ........................ Permits Containing Voluntarily Accepted Emission Limitations 

and Standards.

November 2, 2015 .................. 80 FR 67319 

R18–2–319 ............................. Minor Permit Revisions ............................................................. November 2, 2015 .................. 80 FR 67319 

R18–2–320 ............................. Significant Permit Revisions ..................................................... November 2, 2015 .................. 80 FR 67319 

R18–2–334 ............................. Minor New Source Review ....................................................... November 2, 2015 .................. 80 FR 67319 

R18–2–406 ............................. Permit Requirements for Sources Located in Attainment and 

Unclassifiable Areas.

May 4, 2018 ............................ 83 FR 19631 

R9–3–217, paragraph A ........ Attainment Areas; Classification and Standards ...................... April 23, 1982 .......................... 47 FR 17483 


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12The ADEQ’s SIP-approved minor NSR program 

expressly regulates oxides of nitrogen (NOX) and 

sulfur dioxide (SO2) as PM2.5 precursors at R18–2– 

101(123). 

13The EPA’s implementing regulations also 

include other largely procedural requirements for 

minor NSR programs at 40 CFR 51.160–51.164. 

II. Public Comments and EPA 

Responses 

The EPA’s proposal provided for a 30- 

day public comment period. We 

received one set of comments from 

Arizona Center for Law in the Public 

Interest and the Center for Biological 

Diversity (‘‘the commenters’’). Below, 

we summarize the comments received 

and provide our responses. The full text 

of the comments is available in the 

docket for this action. 

Comment: The commenters state that 

the ADEQ’s minor NSR program is 

inadequate because it does not regulate 

ammonia and volatile organic 

compounds (VOCs) as PM2.5 precursors. 

The commenters argue that the EPA’s 

approval of the 2020 Minor NSR 

submittal will interfere with attainment 

of the PM2.5 National Ambient Air 

Qualtiy Standard (NAAQS) in areas 

under the ADEQ’s jurisdiction that are 

designated nonattainment for PM2.5. The 

commenters argue that this also means 

that the submittal does not comply with 

CAA section 110(l) and Appendix V to 

40 CFR part 51. Further, the 

commenters argue that the 2020 Minor 

NSR submittal is insufficient because it 

does not include a modeling 

demonstration that the regulation of 

VOCs or ammonia is unnecessary to 

ensure protection of the PM2.5 NAAQS. 

Response: As an initial matter, we 

note that the commenters’ argument that 

the ADEQ’s minor NSR program must 

regulate VOCs and ammonia as 

precursors to PM2.5 in PM2.5

nonattainment areas where the ADEQ 

has jurisdiction does not address the 

specific revisions to the ADEQ’s minor 

NSR program that are the focus of the 

EPA’s current action. As explained in 

section I of this SUPPLEMENTARY

INFORMATION section, the EPA previously 

undertook an extensive review of the 

ADEQ’s NSR program (minor NSR, PSD, 

and NNSR) in 2015 to ensure that the 

program met all Clean Air Act 

requirements. In our 2015 NSR action, 

we found that the ADEQ’s updated 

program largely met Clean Air Act 

requirements, but we identified a 

number of specific deficiencies in our 

final action that needed to be corrected 

in order for ADEQ to gain full approval 

from the EPA. Most of the identified 

deficiencies were corrected and 

submitted to the EPA for approval in 

2017 and were approved in our 2018 

Major NSR action. We are currently 

acting on the ADEQ’s 2019–20 NSR 

submittals that correct the remaining 

deficiencies that we identified as the 

bases for our final limited disapproval 

in our 2015 NSR action and that formed 

the basis for the conditional approval in 

our 2018 Major NSR action. The EPA 

found in our 2015 NSR action that the 

ADEQ’s minor NSR program met all the 

requirements for a minor NSR program 

in CAA section 110(a)(2)(C) and 40 CFR 

51.160–51.164 with the exception of 

specific deficiencies that the ADEQ is 

now addressing with the 2020 Minor 

NSR submittal. In light of the recent and 

extensive review and approval by the 

EPA of the ADEQ’s NSR program, we 

find that the commenters’ concerns 

regarding PM2.5 precursors in the 

ADEQ’s minor NSR program are not 

germane to the deficiencies with the 

ADEQ’s minor NSR program that we 

identified previously and that we are 

addressing in this action. Nevertheless, 

we will explain why we disagree with 

the commenters that the ADEQ’s minor 

NSR program must regulate VOCs and 

ammonia as precursors to PM2.5 in the 

areas where the ADEQ has permitting 

jurisdiction, and why we disagree that 

the EPA’s approval of these revisions to 

the ADEQ’s SIP-approved minor NSR 

program is inconsistent with CAA 

section 110(l) and Appendix V to 40 

CFR part 51. 

The commenters are concerned that 

this action will interfere with 

attainment of the PM2.5 NAAQS in 

designated PM2.5 nonattainment areas 

under the ADEQ’s permitting 

jurisdiction because the ADEQ’s minor 

NSR program and the 2020 Minor NSR 

submittal do not specifically regulate 

ammonia and VOC as precursors to 

PM2.5 in the ADEQ’s minor NSR 

program.12 As a result, the commenters 

conclude, the 2020 Minor NSR 

submittal does not meet CAA section 

110(l) and section 2.2(d) of Appendix V 

to 40 CFR part 51. To support their 

concerns, the commenters point 

generally to examples of operations that 

can emit ammonia and VOC, and imply 

that the method to demonstrate that this 

action complies with CAA section 110(l) 

and section 2.2(d) of Appendix V to 40 

CFR part 51 is through a modeling 

demonstration that they assert is 

required by section 2.2(e) of Appendix 

V to 40 CFR part 51. 

To evaluate the commenters’ 

concerns, it is important to understand 

the requirements in the Act governing 

how permitting authorities must address 

precursors in NSR programs for 

nonattainment areas. Part D of title I of 

the Act contains specific requirements 

for the development of an NNSR 

program for major sources (and major 

modifications) in nonattainment areas. 

Among other requirements, in a PM2.5

nonattainment area, the NNSR program 

must apply to major sources of direct 

PM2.5 emissions and to major sources of 

PM2.5 precursors, unless the EPA 

determines that such precursor sources 

do not contribute significantly to PM2.5

levels that exceed the standard in the 

nonattainment area. See CAA section 

189(e). For purposes of the NNSR 

program, the EPA has identified NOX,

SO2, VOCs, and ammonia as precursors 

to PM2.5. See 40 CFR 

51.165(a)(1)(xxxvii)(C)(2). Our proposed 

action explained that we have 

determined that the ADEQ’s NNSR 

program for PM2.5 fully satisfies CAA 

section 189(e), and the commenters do 

not dispute this. The requirements of 

CAA section 189(e) do not, however, 

apply to NSR permitting under the 

minor NSR program. 

The Act’s requirements for minor NSR 

programs are far less prescriptive in 

general than those applicable for NSR 

programs regulating proposed new 

major sources and major modifications. 

CAA section 110(2)(a)(C), which 

governs minor NSR programs, requires 

the ‘‘regulation of the modification and 

construction of any stationary source 

within the areas covered by the plan as 

necessary to assure that national 

ambient air quality standards are 

achieved.’’ (emphasis added) The EPA’s 

implementing regulations for minor 

NSR programs require that such 

programs include legally enforceable 

procedures that enable the state to 

determine whether the construction or 

modification of sources will result in a 

violation of applicable portions of the 

control strategy or interference with 

attainment or maintenance of the 

NAAQS, and, if so, to prevent such 

construction or modification. See 40 

CFR 51.160(a)–(b). States are not 

required to regulate the construction of 

all new or modified stationary sources 

under their minor NSR programs; rather, 

the procedures must identify the types 

and sizes of sources regulated under the 

state’s minor NSR program, and the 

state’s plan must discuss the basis for 

determining which sources will be 

subject to review. 40 CFR 51.160(e).13

Thus, the Act provides considerable 

discretion for permitting authorities to 

develop minor NSR programs 

determined ‘‘necessary’’ to assure the 

NAAQS are achieved in their respective 

geographic areas. Consistent with CAA 

section 110(a)(2)(C) and the 

implementing regulations governing 

minor NSR programs at 40 CFR 51.160– 


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14 2020 Minor NSR submittal at 19; section 

4.4.3.2. See also 82 FR 21711 (May 10, 2017) (EPA 

determination of attainment by the attainment 

date). 

15 2020 Minor NSR submittal at 16; Table 4–2. 

16We also note that the ADEQ’s March 29, 2019 

SIP revision related to ammonia as a PM2.5

precursor provides results from a 2010 ADEQ study 

that determined the speciation of PM2.5 emissions 

in the West Central Pinal nonattainment area. The 

study showed that 90% of PM2.5 emissions in the 

West Central Pinal nonattainment area originate 

from direct PM2.5 sources, and less than 10% from 

PM2.5 precursors. March 29, 2019 SIP submittal at 

11; Table 3–3. 

17 85 FR 83868, 83876 (Dec. 23, 2020). 

18The commenters reference the portion of 

section 2.2(d) that requires SIP submittals to 

‘‘demonstrat[e] that the national ambient air quality 

standards, prevention of significant deterioration 

increments, reasonable further progress 

demonstration, and visibility, as applicable, are 

protected if the plan is approved and 

implemented.’’ See 40 CFR part 51, Appendix V, 

section 2.2(d). 

19Section 2.2(e) of Appendix V requires that a SIP 

submittal include the ‘‘[m]odeling information 

required to support the proposed revision, 

including input data, output data, models used, 

justification of model selections, ambient 

monitoring data used, meteorological data used, 

justification for use of offsite data (where used), 

modes of models used, assumptions, and other 

information relevant to the determination of 

adequacy of the modeling analysis.’’ 

20See 40 CFR 51.166(b)(23)(i). 

51.164, the EPA has determined, as 

explained in our proposal, that the 

ADEQ’s program now meets the relevant 

requirements for a minor NSR program. 

In response to the commenter’s 

specific concerns here, we consider the 

two PM2.5 nonattainment areas in 

Arizona—Nogales and West Central 

Pinal. Regarding the Nogales area, 

where the ADEQ has minor NSR 

permitting jurisdiction, the ADEQ’s 

2020 Minor NSR submittal explains that 

‘‘[t]he Nogales PM2.5 nonattainment area 

was found to have attained the 2006 24- 

hour PM2.5 NAAQS in 2017.’’ 14 Further, 

while the ADEQ’s minor NSR program 

does not specifically regulate VOC as a 

PM2.5 precursor, minor sources of VOC 

are, in fact, regulated by the ADEQ’s 

minor NSR program at a source-wide 

permitting threshold of 20 tons per year. 

The 2020 Minor NSR submittal contains 

an analysis showing that this permitting 

threshold is expected to cover at least 

86% of VOC emissions in areas subject 

to ADEQ permitting jurisdiction.15 For 

the West Central Pinal PM2.5

nonattainment area, the Pinal County 

Air Quality Control District, not the 

ADEQ, has primary permitting 

jurisdiction for minor sources. 

Accordingly, the ADEQ’s minor NSR 

permitting program generally does not 

apply in the West Central Pinal PM2.5

nonattainment area.16

Although the commenters mention 

certain types of operations that may 

emit ammonia and VOCs, the 

commenters do not provide information 

or explanation that demonstrates that 

the ADEQ’s regulating those pollutants 

as precursors to PM2.5 in the PM2.5

nonattainment areas under the ADEQ’s 

jurisdiction as part of the ADEQ’s minor 

NSR program is necessary to achieve the 

PM2.5 NAAQS in any such areas. As 

explained above, the only PM2.5

nonattainment area where the ADEQ 

has primary jurisdiction for minor 

sources, the Nogales area, is already 

attaining the PM2.5 NAAQS. Moreover, 

in addition to regulating direct PM2.5

emissions, the ADEQ’s minor NSR 

program regulates emissions of NOX and 

SO2 as PM2.5 precursors and regulates 

VOC emissions in general. In light of the 

information described above, we find 

that the ADEQ’s determination to not 

regulate sources of ammonia and VOCs 

as PM2.5 precursors in its minor NSR 

program in the PM2.5 nonattainment 

areas under its jurisdiction is reasonable 

and not necessary to ensure that the 

PM2.5 NAAQS are achieved. 

The commenters also indicate that the 

EPA’s approval of the 2020 Minor NSR 

submittal conflicts with the requirement 

in CAA section 110(l) that the EPA 

‘‘shall not approve a revision of a plan 

if the revision would interfere with any 

applicable requirement concerning 

attainment and reasonable further 

progress. . .or any other applicable 

requirement of this chapter.’’ Our 

December 23, 2020 proposed approval 

contained our analysis that our action 

met these requirements of CAA section 

110(l): ‘‘We have determined that our 

action on the 2019–20 NSR submittals 

would, as described herein, strengthen 

the applicable SIP. This action is 

primarily intended to correct numerous 

deficiencies in the ADEQ’s NSR 

program and provides other revisions to 

enhance and update the program. 

Accordingly, this action will not 

interfere with attainment and reasonable 

further progress, or any other applicable 

requirement.’’ 17 The commenters did 

not address this analysis or explain how 

this action to correct deficiencies in the 

ADEQ’s minor NSR program will 

interfere with any applicable 

requirement concerning attainment and 

reasonable further progress or any other 

CAA requirement in the PM2.5

nonattainment areas under the ADEQ’s 

jurisdiction that are of concern to the 

commenter. This action strengthens the 

overall SIP and does not relax any SIP 

requirements related to attaining the 

PM2.5 NAAQS in Arizona. 

The commenters make the related 

argument that the ADEQ’s SIP revision 

does not satisfy section 2.2(d) of 

Appendix V to 40 CFR part 51 because 

it does not regulate VOCs and ammonia 

as precursors to PM2.5 and therefore 

interferes with attainment of the PM2.5

NAAQS in areas under ADEQ’s 

jurisdiction that are designated 

nonattainment for PM2.5.18 As described 

above, the 2019–20 SIP submittals 

contain sufficient information to 

support our conclusion that the ADEQ’s 

decision not to specifically regulate 

VOC and ammonia as PM2.5 precursors 

for its minor NSR program is acceptable 

and will not interfere with attainment of 

the PM2.5 NAAQS. 

Lastly, in response to the commenter’s 

argument that the ADEQ should have 

included a modeling demonstration 

relating to ammonia and VOC as PM2.5

precursors to meet the requirements of 

section 2.2(e) of Appendix V to 40 CFR 

part 51, the commenters have not 

accurately characterized these 

requirements.19 We do not interpret 

section 2.2(e) of Appendix V to require 

that every SIP submittal contain a 

modeling demonstration, as implied by 

the commenters. Instead, when a 

modeling demonstration is necessary 

and is therefore included in a submittal 

to support the SIP revision, then the 

submittal must also contain the 

underlying modeling information 

outlined in section 2.2(e). We find that 

section 2.2(e) of Appendix V is not 

applicable to the 2020 Minor NSR 

submittal because modeling was not 

used to support this SIP revision nor 

was a modeling demonstration required 

in this instance. 

Comment: The commenters consider 

the ADEQ’s minor NSR thresholds of 

one-half the ‘‘significant’’ emission rates 

(SERs) in the PSD program 20 to be 

arbitrary and unsupported by modeling 

or other evidence demonstrating 

protection of the NAAQS, in violation of 

CAA section 110(l) and sections 2.2(d) 

and (e) in Appendix V to 40 CFR part 

51. The commenters argue that merely 

comparing the percentage of emissions 

regulated by the ADEQ’s program to 

other programs does not address 

whether thresholds are ‘‘protective of 

the NAAQS’’. The commenters assert 

that the ADEQ misplaced focus on the 

contributions of current sources in 

nonattainment areas under its 

jurisdiction and whether those areas are 

now violating the NAAQS. Instead, the 

ADEQ should have focused on ensuring 

that additional sources (or new 

modifications of existing sources) do not 

jeopardize attainment or maintenance of 

the NAAQS in the future. 

Response: We respectfully disagree 

with the commenters that the ADEQ has 

not provided an adequate rationale for 


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21 In reviewing the ADEQ’s minor NSR program 

under 40 CFR 51.160(e), we considered it 

appropriate for the ADEQ to exclude emissions 

from its NSR program if such emissions would be 

‘‘inconsequential to attainment or maintenance of 

the NAAQS.’’ 80 FR 67319, 67325. This was the 

same standard that the EPA used in developing the 

permitting thresholds for its minor NSR program for 

Indian country. 76 FR 38748, 38758 (Jul. 1, 2011). 

22 Id. 

23 76 FR 38748 (July 1, 2011). 

24 71 FR 48695, 48701–48703 (Aug. 21, 2006). 

25 76 FR 38748, 38754. 

26See Appendix A of the ADEQ’s 2012 NSR SIP 

submittal at 1547–1549 for a detailed discussion of 

the ADEQ’s approach and analysis. See also, the 

Technical Support Document for the EPA’s Notice 

of Proposed Rulemaking, Revision to the Arizona 

State Implementation Plan for the Arizona 

Department of Environmental Quality, March 2015 

(‘‘EPA’s 2015 TSD’’) at 22–25. The ADEQ’s 

‘‘permitting exemption thresholds’’ are found at 

R18–2–101(101). The thresholds are ton per year 

values set for various pollutants that determine 

when a permit or registration is required for new 

sources and when minor NSR review is triggered for 

modifications. If potential source-wide emissions 

from all regulated pollutants are below the 

permitting exemption thresholds, then the source is 

‘‘exempt’’ from the ADEQ’s permitting and 

registration program. 

27See 2020 Minor NSR submittal at 14–20 for the 

full discussion. 

its permitting exemption thresholds for 

minor sources in nonattainment areas 

and minor sources of PM2.5 in 

attainment areas under CAA section 

110(l) and Appendix V to 40 CFR part 

51. 

First, we note that with the exception 

of the thresholds for PM2.5 sources, in 

our 2015 NSR action, the EPA 

previously approved the ADEQ’s 

permitting thresholds for minor NSR as 

they apply in attainment areas, and, 

accordingly, those thresholds were not 

changed as part of the 2020 Minor NSR 

submittal. The EPA’s prior approval was 

based on the ADEQ’s demonstration that 

the emissions from the sources and 

projects to be exempted from its minor 

NSR program under these thresholds 

were inconsequential to attainment or 

maintenance of the NAAQS.21 However, 

in our 2015 NSR action, we also 

determined that the ADEQ had not 

provided a rationale for the PM2.5

permitting exemption threshold, nor 

had it provided an adequate rationale 

for why the permitting exemption 

thresholds were appropriate for 

nonattainment areas. 22 In this action, 

we are considering only the 2020 Minor 

NSR submittal and the ADEQ’s rationale 

for its permitting exemption thresholds 

as they apply to minor sources in 

nonattainment areas, and to minor 

sources of PM2.5 in attainment areas. 

The commenters specifically take 

issue with the ADEQ’s comparing the 

percentage of emissions regulated by its 

NSR program to the percentage of 

emissions regulated by other NSR 

programs, and assert that the ADEQ’s 

approach should focus more on future 

sources of emissions and ensuring that 

such sources do not jeopardize the 

NAAQS. As described below, the 

ADEQ’s approach did not rest solely on 

comparing its permitting thresholds to 

other programs, and we find that the 

approach ensures that the ADEQ’s 

minor NSR program reviews the 

necessary sources to ensure attainment 

and maintenance of the NAAQS. 

Prior to 2012, the ADEQ’s minor NSR 

program required permitting of nonmajor sources with potential emissions 

of a criteria pollutant at or above the 

SERs from the PSD program reflected in 

40 CFR 51.166(b)(23)(i). To address 

concerns raised by the EPA regarding 

these historic permitting thresholds, the 

ADEQ assessed other potential lower 

permitting thresholds for its minor NSR 

program and ultimately selected 

revised, lower thresholds. In 2012, the 

ADEQ chose to use a method similar to 

the method that the EPA used to 

develop permitting thresholds under its 

minor NSR program applicable in 

Indian country, known as the ‘‘Tribal 

Minor NSR rule.’’ 23 To inform its 

selection of minor NSR permitting 

thresholds in developing the Tribal 

Minor NSR rule, the EPA conducted a 

source distribution analysis using data 

from the National Emissions Inventory. 

The EPA’s analysis concluded that the 

percentage of emissions that would be 

exempt from minor NSR under the 

Tribal Minor NSR rule’s thresholds 

would be small (less than 1.5% of total 

emissions for each pollutant), while the 

program’s permitting thresholds would 

require only 14–58% of stationary 

sources (varying based on the individual 

pollutant) to obtain permits or register 

under the Tribal Minor NSR rule. The 

EPA’s analysis determined that this 

approach provided ‘‘evidence that 

sources with emissions below the 

proposed minor NSR thresholds will be 

inconsequential to attainment and 

maintenance of the NAAQS.’’ 24 We 

stated that the permitting thresholds for 

the minor NSR program applicable in 

Indian country are ‘‘not intended to 

establish a new set of minimum criteria 

that a Tribe or a state would need to 

follow in developing its own minor 

source permitting program.’’ 25

Nevertheless, the approach taken by the 

EPA in developing the thresholds in the 

Tribal Minor NSR rule represents one 

approach that EPA has found to be 

appropriate in establishing such 

thresholds. 

To assess potential thresholds for its 

minor NSR program, the ADEQ applied 

a similar approach to a local data set. 

During the stakeholder process, the 

ADEQ proposed two alternative 

scenarios for its revised minor NSR 

thresholds: One that generally used one 

half of the PSD SERs (Scenario 1) and 

one that generally used one quarter of 

the PSD SERs (Scenario 2). The ADEQ’s 

analysis looked at the percentage of 

emissions that would be regulated at the 

two thresholds and concluded that 

‘‘both scenarios result in a relatively 

large percentage of emissions being 

subject to regulation compared to the 

percentage of sources brought into the 

program.’’ The results of the analysis 

showed that using Scenario 2 for the 

minor NSR emission thresholds rather 

than Scenario 1 would result in 

significantly more coverage of carbon 

monoxide (CO) and SO2 emissions 

under the ADEQ’s minor NSR program. 

However, the ADEQ reasoned that 

stationary source emissions of CO are 

generally dwarfed by mobile source 

emissions and do not contribute 

significantly to nonattainment of the CO 

NAAQS. Also, the ADEQ reasoned that 

in the areas within Arizona that are 

subject to its minor NSR program, the 

sources that could contribute to 

noncompliance with the SO2 NAAQS 

are well-defined and consist of large 

industrial sources already subject to the 

permitting program. The ADEQ 

concluded, based on the above 

considerations, that for purposes of 

minor NSR, use of the Scenario 2 

thresholds would not offer any 

substantial benefits over Scenario 1, and 

set numerical exemption thresholds for 

the pollutants in its minor NSR program 

that equate to one half of the PSD 

SERs.26

In response to the EPA’s 

determination in our 2015 NSR action 

that the ADEQ needed to justify the 

chosen permitting thresholds for PM2.5

and to further justify the thresholds as 

they apply in nonattainment areas, in its 

2020 Minor NSR submittal, the ADEQ 

continued to build on its prior analyses 

supporting the current permitting 

thresholds in its minor NSR program.27

First, the ADEQ updated its prior source 

distribution analysis to use the National 

Emissions Inventory, the same data set 

that the EPA used for its analysis for the 

Tribal Minor NSR program, and to 

include PM2.5 emissions. The analysis 

shows that the ADEQ’s NSR program is 

expected to cover approximately 98% of 

PM2.5 emissions in counties where the 

ADEQ has minor source permitting 

jurisdiction and approximately 96% of 

PM2.5 emissions in PM2.5 nonattainment 

areas where the ADEQ has minor source 

permitting jurisdiction. Further, the 


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28Technical Support Document for EPA’s Notice 

of Proposed Rulemaking: Air Plan Approval; 

Arizona; Stationary Sources; New Source Review 

Updates, November 2020 (‘‘EPA’s 2020 TSD’’) at 15. 

29The ADEQ’s program requires permitting or 

registration for new and existing sources. While a 

NAAQS review is generally only triggered for new 

sources or modifications, the ADEQ’s permitting of 

existing sources provides additional protection that 

such sources are also complying with all other 

applicable CAA requirements. 

30The NSR program is only one aspect of the 

CAA requirements that must be implemented to 

ensure attainment and maintenance of the NAAQS. 

The NSR program is generally intended to allow for 

increases in emissions if it can be demonstrated that 

the increases will not interfere with attainment. 

Among other CAA programs, the comprehensive set 

of requirements found in CAA title I, part D are 

designed to ensure that State and local authorities 

with jurisdiction over nonattainment areas require 

the necessary reductions to reach attainment. 

31As explained above, the commenters do not 

accurately characterize the SIP submittal 

completeness criteria in Section 2.2(e) of Appendix 

V to 40 CFR part 51 as it relates to modeling. We 

find that section 2.2(e) is not applicable to the 2020 

Minor NSR submittal because it did not contain 

modeling to support the SIP revision, nor is 

modeling required in this instance. 

32As noted previously, the commenters do not 

accurately characterize section 2.2(e) of Appendix 

V, which requires that SIP submittals include 

certain information that supports modeling when 

modeling is otherwise required to be conducted for 

a SIP revision. The CAA does not require all SIP 

submittals to contain modeling, and modeling was 

not included in or required to support the 2020 

Minor NSR submittal. Therefore, we continue to 

find that section 2.2(e) of Appendix V is not 

applicable to the 2020 Minor NSR submittal in 

general, nor does it apply specifically to the ADEQ’s 

demonstration supporting the exemption of 

agricultural equipment used in normal farm 

operations. 

33See ARS 49–426(B), which states, in part, in 

reference to the State law requirements for 

obtaining air permits: ‘‘The provisions of this 

section shall not apply to motor vehicles, to 

agricultural vehicles or agricultural equipment used 

in normal farm operations, or to fuel burning 

equipment which, at a location or property other 

than a one or two family residence, is rated at less 

than one million British thermal units per hour.’’ 

(emphasis added) 

34See 40 CFR 51.160(e): ‘‘The procedures must 

identify types and sizes of facilities, buildings, 

structures, or installations which will be subject to 

Continued 

ADEQ considered the types of emission 

sources in each of the nonattainment 

areas where it has minor source 

permitting jurisdiction that contribute to 

nonattainment. For example, the 

Hayden and Miami SO2 nonattainment 

areas are attributable to the copper 

smelters operating in each area, and the 

Nogales nonattainment area for 

particular matter with an aerodynamic 

diameter less than or equal to 10 

microns (‘‘PM10’’) is attributable to 

paved road dust, construction, and 

residential wood burning. As we 

summarized in the TSD for our 

December 23, 2020 proposed action, 

‘‘[t]his discussion shows that minor 

sources are not currently significant 

contributors to the nonattainment issues 

in these areas.’’ 28

In consideration of the information 

summarized in this response, we 

disagree with the commenters that the 

ADEQ’s approach to revising its minor 

source permitting thresholds for PM2.5

and in designated nonattainment areas 

where it has minor source permitting 

jurisdiction was arbitrary and 

unsupported. We find that the ADEQ 

has provided sufficient evidence that its 

NSR program will apply to the vast 

majority of emissions where the ADEQ 

has permitting jurisdiction, including in 

Arizona’s nonattainment areas, and 

including PM2.5 emissions in attainment 

areas.29 As a result, we conclude that 

those emissions exempted from the 

ADEQ’s NSR program under its minor 

NSR permitting exemption thresholds 

will be inconsequential to attainment 

and maintenance of the NAAQS. 

While we agree with the commenters’ 

general proposition that the NSR 

program focuses on the review of new 

sources and modifications to existing 

sources, we disagree that this means 

that the rationale and analysis provided 

by the ADEQ to support its permitting 

exemption thresholds is inadequate. 

The commenters have not suggested or 

provided an alternative analysis that 

they believe would be appropriate to 

demonstrate the insufficiency of the 

minor NSR thresholds at issue, other 

than a generic reference to ‘‘modeling.’’ 

We find the ADEQ’s rationale 

persuasive and find that the ADEQ has 

demonstrated that the permitting 

thresholds it has established by 

considering local conditions will 

capture the types and sizes of sources 

that are necessary for review to ensure 

such sources will not interfere with 

attainment and maintenance of the 

NAAQS in the areas where the ADEQ 

has minor NSR permitting 

jurisdiction.30 Thus, the additional 

analysis and information provided by 

the ADEQ in the 2020 Minor NSR 

submittal is sufficient for demonstrating 

that the permitting thresholds for minor 

sources in nonattainment areas and 

minor sources of PM2.5 in attainment 

areas meet the requirements of CAA 

section 110(l) and Appendix V to 40 

CFR part 51 31 and will not interfere 

with attainment and maintenance of the 

NAAQS. 

Comment: The commenters assert that 

the 2020 Minor NSR submittal fails to 

demonstrate under 40 CFR 51.160(e) 

that review of ‘‘agricultural equipment 

used in normal farm operations’’ under 

the ADEQ’s minor NSR program is not 

needed for the ADEQ’s program to meet 

federal NSR requirements for attainment 

and maintenance of the NAAQS or 

review for compliance with the control 

strategy. The commenters take issue 

with several aspects of the ADEQ’s 

rationale, that we discuss in detail 

below, and further conclude that this 

exemption violates CAA section 110(l) 

and sections 2.2(d) and (e) of Appendix 

V to 40 CFR part 51. 

Response: As discussed below, we 

respectfully disagree with the 

commenters that the 2020 Minor NSR 

submittal does not demonstrate that the 

State’s exemption for ‘‘agricultural 

equipment used in normal farm 

operations’’ in its NSR program is 

approvable under 40 CFR 51.160(e). The 

ADEQ’s submittal demonstrates that 

regulation of these exempt sources 

under its minor NSR program is not 

needed for ADEQ’s program to meet 

federal NSR requirements for attainment 

and maintenance of the NAAQS or 

review for compliance with the control 

strategy. As the ADEQ has explained in 

detail, this exemption could potentially 

apply only to a very narrow group of 

minor sources that would not otherwise 

be exempt from minor NSR review 

under exemptions already approved by 

the EPA in our 2015 NSR action. 

Further, the ADEQ retains authority to 

require a permit even for the sources 

that will fit within this exemption if it 

determines that doing so is necessary to 

protect the NAAQS or enforcement of 

the control strategy. For these reasons, 

we also disagree that the exemption 

violates CAA section 110(l) and section 

2.2(d) of Appendix V to 40 CFR part 

51.32

The State of Arizona exempts 

‘‘agricultural equipment used in normal 

farm operations’’ from the general 

requirement to obtain an air permit.33

The ADEQ’s permitting regulations 

implement this exemption by exempting 

‘‘agricultural equipment used in normal 

farm operations’’ from the requirement 

to obtain a registration or permit at R18– 

2–302(C). R18–2–302(C) makes clear 

that this exemption does not apply if the 

source is a ‘‘major source’’ or if 

‘‘operation without a permit would 

result in a violation of the [Clean Air] 

Act.’’ R18–2–302(C)(2) also clarifies that 

‘‘agricultural equipment used in normal 

farm operations’’ does not include 

equipment classified as a source that 

requires a permit under title V of the 

Act or that is subject to a standard under 

40 CFR parts 60, 61, or 63. 

We identified this exemption as one 

of the bases for our limited disapproval 

of the ADEQ’s 2012 NSR SIP submittal 

in our 2015 NSR action because the 

submittal did not adequately justify the 

exemption as required by 40 CFR 

51.160(e),34 and it was unclear how the 


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review under this section. The plan must discuss 

the basis for determining which facilities will be 

subject to review.’’ 

35See section 5.2.2.3 of the EPA’s 2015 TSD at 

26–27 and 80 FR 67319, 67323. 

36Attorney General’s Opinion, 2 (Nov. 15, 1993), 

Appendix D of the 2020 Minor NSR submittal. 

37 61 FR 55910, 55915 (Oct. 30, 1996). 

38Fugitive emissions are defined in the ADEQ’s 

SIP-approved regulations at R18–2–101(59) as 

‘‘those emissions which could not reasonably pass 

through a stack, chimney, vent, or other 

functionally equivalent opening.’’ See section 4.2 of 

the 2020 Minor NSR submittal at 9, n.14. 

39See also 80 FR 67319, 67320, Table 1. 

exemption in state law applied in the 

context of the ADEQ’s NSR program.35

In response to this limited disapproval, 

the ADEQ provided a detailed 

discussion of the exemption in the 2020 

Minor NSR submittal. As summarized 

below, the ADEQ’s 2020 Minor NSR 

submittal demonstrates that the 

exemption is only available to a limited 

set of minor sources not otherwise 

exempt under exemptions we have 

already approved into the Arizona SIP 

as part of the ADEQ’s NSR program, and 

the program’s potential exemption of 

such sources would be inconsequential 

to attainment and maintenance of the 

NAAQS. 

First, the 2020 Minor NSR submittal 

clarified that the exemption at R18–2– 

302(C) represents the ADEQ’s 

interpretation of the agricultural 

exemption in Arizona Revised Statutes 

(ARS) section 49–426(B): 

This rule represents ADEQ’s official 

implementation and interpretation of the 

statutory exemption under its rulemaking 

authority in ARS §§ 49–425 and 49–426(B). 

The rule has been recognized as valid by the 

Arizona Attorney General in its opinion 

supporting the state’s Title V program in 

1993.36 In approving Arizona’s Title V 

program in 1996, EPA deferred to this 

opinion but stated that it would revisit this 

issue if ‘‘a successful legal challenge to [the 

regulatory exemption] occurs.’’ 37 In the 

subsequent 23 years, there has been no such 

challenge. 

Section 4.2.1 of the 2020 Minor NSR 

submittal at 10. 

Second, the ADEQ confirmed that the 

ADEQ interprets its permitting 

requirements such that its permitting 

determinations (including for the 

registration program component of its 

minor NSR program) are made on a 

source-wide basis. As a result, if 

‘‘agricultural equipment used in normal 

farm operations’’ is located at the same 

stationary source as equipment that 

requires a permit, then the ADEQ’s 

permit requirements, and potentially 

NSR, extend to the entire source and all 

of its pollutant-generating activities, 

including any equipment that might 

otherwise meet the definition of 

‘‘agricultural equipment used in normal 

farm operations’’. These two 

clarifications mean that the agricultural 

equipment exemption is potentially 

available only to a subset of minor 

sources. See section 4.2.2 of the 2020 

Minor NSR submittal at 10–11. 

While the term ‘‘normal farm 

operations’’ is not specifically defined 

by statute or rule, the ADEQ stated that 

the State of Arizona’s Agricultural Best 

Management Practices (Ag BMP) 

program for commercial farming 

operations in PM10 nonattainment areas 

provides guidance on the State’s 

interpretation of the types of activities 

that constitute normal farm operations. 

This includes activities such as tillage, 

planting, and harvesting; areas of a 

commercial farm that are not normally 

in crop production (i.e., fallow); areas of 

a commercial farm that are normally in 

crop production; significant agricultural 

earthmoving activities; traffic over 

unpaved access connections or unpaved 

roads or feed lanes; animal waste 

handling and transporting; arenas, 

corrals, and pens; and canals. The 

ADEQ stated that it interprets the 

normal farm operations exemption as 

applicable to the types of equipment 

used for these activities and to crop and 

feed processing equipment that 

produces only fugitive emissions. In the 

ADEQ’s experience, farm emissions 

tend to consist almost exclusively of 

fugitive dust generated by the 

disturbance of soils. It is important to 

note that the ADEQ’s current SIPapproved NSR program already exempts 

fugitive emissions,38 at R18–2–302(F), 

in determining whether a stationary 

source is subject to minor NSR 

permitting requirements. See sections 

4.2.3 and 4.2.4 of the 2020 Minor NSR 

submittal at 11–12.39 As a result, most 

of the sources that would meet the 

definition of ‘‘agricultural equipment 

used in normal farm operations’’ would 

be sources of fugitive emissions that are 

already exempt from minor NSR under 

the ADEQ’s SIP-approved minor NSR 

program. 

The ADEQ also recognized that it is 

possible for equipment used in normal 

farm operations to be a part of a 

stationary source that produces stack 

(i.e., non-fugitive) emissions greater 

than the ADEQ’s permitting exemption 

thresholds, and it may also be possible 

for normal farm operations themselves 

to be configured in such a way as to 

produce stack emissions. However, the 

ADEQ believes that, in most cases, such 

a stationary source would not qualify for 

the permitting exemption because 

equipment used in normal farm 

operations ‘‘does not include equipment 

classified as a source that requires a 

permit under Title V of the Act, or that 

is subject to a standard under 40 CFR 

60, 61, or 63.’’ Because the ADEQ 

determines permit applicability on a 

source-wide basis, if a stationary source 

that engaged in normal farm operations 

qualified as a CAA title V source or 

included equipment subject to a New 

Source Performance Standard (NSPS) or 

National Emission Standard for 

Hazardous Air Pollutants (NESHAP) in 

40 CFR parts 60, 61, or 63, then the 

entire source would require a permit, 

and potentially be subject to minor NSR 

if its emissions were above the ADEQ’s 

minor NSR permitting exemption 

thresholds. In the ADEQ’s experience, 

most permitted sources include one or 

more pieces of equipment subject to an 

NSPS, such as a boiler, stationary 

engine, or fuel storage tank. The ADEQ 

concluded that it is likely that if 

equipment used in normal farm 

operations were collocated with 

equipment with stack emissions 

exceeding the permitting exemption 

thresholds, at least some of that 

equipment would be subject to an 

NSPS, and therefore the normal farm 

operations exemption would not apply. 

See section 4.2.5 of the 2020 Minor NSR 

submittal at 12–13. 

Finally, the ADEQ explained that 

under R18–2–302(C), equipment used in 

normal farm operations is not exempt if 

‘‘operation [of the equipment] without a 

permit would result in a violation of the 

Act,’’ which provides a final safeguard 

for its NSR program. In a situation 

where agricultural equipment used in 

normal farm operations with stack 

emissions above the permitting 

exemption thresholds used the 

exemption to avoid permitting, the 

ADEQ would invoke this provision as 

necessary to ensure that any such source 

does not endanger attainment or 

maintenance of the NAAQS or 

enforcement of the control strategy. The 

ADEQ explained that whenever it 

becomes aware of such a source through 

citizen complaint, inspection of the 

facility under the Ag BMP program, 

inspection of a nearby or related facility, 

notice from a building permit agency, or 

other means, the ADEQ will evaluate 

the facility using the methodology in 

R18–2–302.01(C) to determine whether 

it should be subject to permitting and 

minor NSR. See section 4.2.5 of the 

2020 Minor NSR submittal at 13. 

In our proposed action, we found that 

the ADEQ had demonstrated that its 

exemption for agricultural equipment 

used in normal farm operations is 

extremely limited in scope, and the 

potential sources exempted from 

permitting would be inconsequential to 

attainment and maintenance of the 


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40 85 FR 83868, 83873. 

41The commenters also state that ‘‘the fact that 

no one has challenged [R18–2–302(C)] does not 

mean a challenge could not occur in the future.’’ 

This concern appears to address the ADEQ’s 

reference to the fact that the Arizona Attorney 

General issued an opinion recognizing the validity 

of this exemption in support of the State’s Title V 

program in 1993. See section 4.2.1 of the 2020 

Minor NSR submittal at 10. As the ADEQ 

explained, the EPA stated in 1996 that it would 

defer to this opinion of the Arizona Attorney 

General in the absence of a successful legal 

challenge to the regulation. The commenters did 

not otherwise explain how this concern affects the 

approvability of the 2020 Minor NSR submittal. 

42See the ADEQ’s July 2, 2014 supplement to the 

2012 NSR SIP submittal at 8–9. 

43We note that the commenters’ general concerns 

about the sufficiency of the Arizona Ag BMP 

program in the Phoenix and West Pinal PM10

nonattainment areas are outside the scope of this 

action on revisions to the ADEQ’s minor NSR 

program. 

NAAQS. We stated that our 

determination was based on the ADEQ’s 

interpretation of the narrow manner in 

which the exemption applies, the 

limited types of operations that are 

considered to be ‘‘normal farm 

operations,’’ and the ADEQ’s retention 

of authority to address any potentially 

exempt sources that may endanger 

attainment or maintenance of the 

NAAQS or enforcement of the control 

strategy. We agreed that the vast 

majority of these operations are likely 

already exempted from the ADEQ’s SIPapproved minor NSR program under the 

general exemption for excluding fugitive 

emissions in permitting applicability 

determinations. We concluded that the 

ADEQ’s basis and explanation for the 

exemption from minor NSR review for 

agricultural equipment used in normal 

farm operations was acceptable.40

The commenters question certain 

aspects of the ADEQ’s explanation and 

the EPA’s rationale for approving the 

agricultural exemption as described 

above. First, the commenters disagree 

with the ADEQ’s explanation of the 

permit exemption not being applicable 

to sources that are subject to a standard 

under 40 CFR parts 60, 61, or 63 or that 

are title V sources. The commenters do 

not see how this interpretation, which 

they say results in a ‘‘blanket’’ 

exemption for minor sources from 

permitting, is protective of the NAAQS. 

In response, this explanation simply 

clarifies the scope of the exemption by 

confirming that major sources and 

sources subject to a standard under 40 

CFR parts 60, 61, or 63 cannot use the 

exemption. We disagree with the 

commenters that this interpretation by 

the ADEQ results in a ‘‘blanket’’ 

exemption for minor sources. Among 

other things, we note that sources that 

are subject to a standard under 40 CFR 

parts 60, 61, or 63 are often minor 

sources. The ADEQ has clarified that if 

any aspect of a stationary source is 

subject to one of these federal standards, 

then the entire stationary source, 

including any ‘‘agricultural equipment 

used in normal farm operations,’’ 

becomes subject to the ADEQ’s 

permitting program.41

Second, the commenters take issue 

with the ADEQ’s explanation that it 

expects the overwhelming majority of 

emissions from ‘‘agricultural equipment 

used in normal farm operations’’ to be 

fugitive emissions. The commenters 

assert that the fact that most of these 

exempted emissions are expected to be 

fugitive does not explain how the 

exemption is protective of the NAAQS. 

In response, it is important to 

understand the context for this 

explanation from the ADEQ. In our 2015 

NSR action, as part of our limited 

approval and limited disapproval of the 

ADEQ’s NSR program, the EPA 

approved of the ADEQ minor NSR 

program’s treatment of fugitive 

emissions in determining when a permit 

is required. The ADEQ’s minor NSR 

program requires fugitive emissions to 

be included in permit applicability 

determinations for certain industrial 

source categories listed in R18–2– 

101(23), such as Portland cement plants, 

primary lead smelters, primary copper 

smelters, and fossil-fuel-fired steam 

electric plants; and for sources which, 

as of August 7, 1980, were being 

regulated under section 111 or 112 of 

the Act. Fugitive emissions are not 

included in permit applicability 

determinations for any other minor 

sources; however, fugitive emissions are 

reviewed in minor NSR permit actions 

for any source triggering review because 

of non-fugitive emissions. See R18–2– 

101(12), R18–2–101(128), and R18–2– 

302(F). In our 2015 NSR action, we 

approved the ADEQ’s minor NSR 

program under 40 CFR 51.160(e), 

including its treatment of sources of 

fugitive emissions, with the exception of 

the specific limited disapproval issues 

that we identified and that the ADEQ is 

addressing in the 2020 Minor NSR 

submittal. See section 5.2.2.3 of the 

EPA’s 2015 TSD at 26–27; 80 FR 67319, 

67323, 67332. In its 2020 Minor NSR 

submittal, the ADEQ is clarifying that 

the overwhelming majority of sources 

that could potentially use the 

agricultural equipment permit 

exemption are fugitive emissions 

sources that the EPA already approved 

for exemption from determining 

whether a permit is required, in our 

2015 action. As a result, the agricultural 

equipment exemption does not create an 

additional large category of sources 

exempt from minor NSR permitting. 

The commenters, however, further 

argue that fugitive dust emissions from 

agricultural equipment are primarily 

addressed through the State’s Ag BMP 

program, and that ‘‘experience with the 

Ag BMP program in both Maricopa 

County and Pinal County has 

demonstrated that it is wholly 

inadequate to ensure compliance with 

the PM10 NAAQS.’’ The commenters are 

concerned that the two PM10

nonattainment areas in Maricopa and 

Pinal counties continue to violate the 

NAAQS despite the adoption of the Ag 

BMP program. The commenters point to 

recent exceedances of the PM10 NAAQS 

in the Phoenix planning area (which 

covers portions of Maricopa and Pinal 

counties) and the fact that the West 

Pinal nonattainment area did not attain 

the PM10 standard by the attainment 

date and was recently reclassified to 

serious nonattainment for PM10. While 

the nonattainment issues in these areas 

are concerning, it is important to 

recognize that the Maricopa County Air 

Quality Department and Pinal County 

Air Quality Control District, rather than 

the ADEQ, have original jurisdiction for 

permitting minor sources in these areas 

of Arizona,42 thus the ADEQ’s minor 

NSR program would generally be 

inapplicable in these areas. Given that 

the ADEQ’s minor NSR program does 

not generally extend to sources in the 

Phoenix and West Pinal PM10

nonattainment areas, the commenters’ 

concerns about the use of the Ag BMP 

program to address fugitive dust in the 

Phoenix and West Pinal PM10

nonattainment areas do not indicate that 

the ADEQ’s regulation of exempt 

agricultural equipment used in normal 

farm operations in other areas that are 

within the ADEQ’s minor NSR 

permitting jurisdiction is necessary for 

attainment and maintenance of the 

NAAQS.43

Third, the commenters question the 

ADEQ’s statement that ‘‘[i]n the 

overwhelming majority of the remaining 

cases, equipment used in normal farm 

operations will be located at a stationary 

source that either qualifies as a title V 

source or includes equipment subject to 

a new source performance standard 

(NSPS)’’. The commenters believe that 

the ADEQ has not supported this claim. 

The commenters are also concerned 

because they claim that the NSPS 

standards do not apply during periods 

of startup, shutdown, and malfunction, 

while the NAAQS apply at all times. We 

disagree that the ADEQ did not support 

this claim. Section 4.2.5 of the 2020 

Minor NSR submittal provides the 


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44 2020 Minor NSR submittal at 12–13. 

45Section 4.2.5 of the 2020 Minor NSR submittal 

at 12; see also the detailed discussion in section 

4.2.5 of the 2020 Minor NSR submittal at 12–13. 

46On the issue of the NSPS standards not 

applying during periods of startup, shutdown, or 

malfunction (we disagree with this broad 

categorization), while the NAAQS do, we believe 

the commenters misunderstand how the ADEQ’s 

permitting program works and how the normal farm 

operations exemption would apply to a source that 

includes equipment subject to an NSPS. The ADEQ 

does not allow stationary sources to use the 

agricultural equipment exemption to avoid NSR 

review if the stationary source is also subject to a 

standard under 40 CFR parts 60, 61, or 63. This 

means that the entire stationary source becomes 

subject to the ADEQ’s permitting program, 

including potential NAAQS reviews for new or 

modified sources, if even a single piece of 

equipment is subject to an NSPS. The way the 

various NSPS apply in general during periods of 

startup, shutdown, or malfunction is not germane 

to the scope of the normal farm operations 

exemption. 47 2020 Minor NSR submittal at 9. 

48See section 5.2.2.3 of the EPA’s 2015 TSD at 

26–27; 80 FR 67319, 67323. 49See section 4.3 of the 2020 Minor NSR 

submittal at 13–14. 50Trivial activities under the ADEQ’s permitting 

program are defined R18–2–101(146). 

ADEQ’s rationale.44 For example, the 

submittal explains that, in the ADEQ’s 

experience, most permitted sources 

include one or more pieces of 

equipment subject to an NSPS, such as 

boilers, stationary engines, or fuel 

storage tanks. The ADEQ clarified that 

a stationary source subject to such a 

standard could not make use of the 

agricultural equipment exemption. 

The ADEQ’s submittal further 

explains that under section 111 of the 

Clean Air Act, EPA is required to 

maintain a list of, and adopt NSPS for, 

all categories of sources that cause or 

significantly contribute to ‘‘air pollution 

which may reasonably be anticipated to 

endanger public health or welfare.’’ The 

ADEQ notes that, consistent with the 

breadth of this charge, the EPA has 

adopted standards for dozens of 

common sources of criteria pollutants, 

criteria pollutant precursors, greenhouse 

gases, and other pollutants. The ADEQ 

reasons that it is therefore likely that if 

equipment used in normal farm 

operations were collocated with 

equipment with stack emissions 

exceeding the permitting exemption 

thresholds, at least some of that 

equipment would be subject to an 

NSPS, and the exemption would not 

apply.45

We believe the ADEQ’s explanation to 

be sufficiently supported based on the 

ADEQ’s knowledge and experience with 

the pollutant-generating activities it 

oversees.46

Finally, the commenters challenge the 

ADEQ’s statement that ‘‘[i]n the few, if 

any, cases where equipment used in 

normal farm operations is located at a 

non-title V source that has stack 

emissions above the permitting 

exemption thresholds but does not 

include NSPS or NESHAP equipment, 

ADEQ retains the authority to require a 

permit to the extent necessary to assure 

protection of the NAAQS and the 

control strategy.’’ 47 The commenters 

express concern because they are 

unclear on how the ADEQ would know 

that a permit is needed or that there is 

a potential NAAQS issue if sources 

aren’t required to submit applications 

for review. We understand the 

commenters’ concern on this issue, 

because the NSR program is intended to 

require review of sources prior to 

construction or modification to ensure 

that sources and modifications are 

constructed in a manner that will not 

cause or contribute to a NAAQS 

violation. However, our approval of the 

ADEQ’s agricultural equipment 

exemption under 40 CFR 51.160(e) is 

based on the totality of the information 

presented by the ADEQ in the 2020 

Minor NSR submittal. The ADEQ has 

demonstrated that the exemption creates 

a narrow category of sources that may be 

exempt from minor NSR review, as 

compared to the program we have 

already approved. However, in the 

potential instances where a stationary 

source is otherwise not required to 

obtain a permit in advance, the ADEQ 

has clarified that it has the authority to 

later require a permit and limit 

operations to protect the NAAQS. That 

is, minor sources defined as agricultural 

equipment used in normal farm 

operations cannot operate in a manner 

that would interfere with attainment 

and maintenance of the NAAQS by 

relying on the permitting exemption in 

State law. 

In sum, the ADEQ has provided a 

detailed and well-supported rationale 

for its exemption of ‘‘agricultural 

equipment used in normal farm 

operations’’ from its minor NSR 

program, and demonstrated that any 

potentially exempted sources are 

inconsequential to attainment and 

maintenance of the NAAQS. Further, 

because the exemption will not interfere 

with the NAAQS, it is consistent with 

CAA section 110(l) and section 2.2(d) of 

Appendix V to 40 CFR part 51. 

Comment: The commenters state that 

the ADEQ failed to justify the 

exemption for certain small stationary 

fuel burning equipment rated at less 

than one million British thermal units 

per hour (MMBtu/hr) found in Arizona 

state law. The commenters are 

concerned that the ADEQ’s rationale 

does not justify the exemption or ensure 

protection of the NAAQS, as the ADEQ 

did not present modeling or other 

evidence in support of the exemption or 

to support that this equipment would 

not otherwise require a permit. 

Response: We disagree with the 

commenters that the ADEQ has not 

adequately justified the Arizona state 

law exemption for small fuel burning 

equipment (those rated at less than 1 

MMBtu/hr) in ARS section 49–426(B) 

within the context of its NSR program. 

The ADEQ’s 2020 Minor NSR submittal 

provides an analysis of the state law 

exemption because the EPA identified it 

as a limited disapproval issue in our 

2015 NSR action. In our 2015 NSR 

action, we found that the ADEQ’s 2012 

NSR submittal did not describe how the 

state law exemption for small fuel 

burning equipment applied in the 

context of its NSR program. Further, to 

the extent the ADEQ’s NSR program 

exempts some sources from minor NSR 

review under the state law exemption, 

we found that the ADEQ needed to 

provide an adequate justification under 

40 CFR 51.160(e).48

In the 2020 Minor NSR submittal, the 

ADEQ confirmed that it interprets the 

exemption as (1) being available only to 

those stationary sources that consists 

‘‘solely of equipment with a cumulative 

heat input rate’’ of less than 1 MMBtu/ 

hr, and (2) having already been 

effectively SIP-approved by the EPA 

because all such equipment falls under 

the ADEQ’s existing SIP-approved 

exemption for ‘‘categorically exempt 

activities’’ at R18–2–302(C)(1) and R18– 

2–101(23).49

As explained by the ADEQ in the 

2020 Minor NSR submittal, the EPA 

reviewed the ADEQ’s permitting and 

registration exemption for ‘‘categorically 

exempt activities’’ in our 2015 NSR 

action. R18–2–302(C) provides that a 

stationary source that consists solely of 

a single ‘‘categorically exempt activity’’ 

plus any combination of trivial 

activities 50 does not require a permit or 

registration, unless the source is a major 

source or operation without a permit 

would result in a violation of the Act. 

The ADEQ defines a ‘‘categorially 

exempt activity’’ at R18–2–101(24) and 

it includes various categories of smaller 

fuel-burning equipment. For example, 

one category is ‘‘any combination of 

diesel-, natural gas- or gasoline-fired 

engines with cumulative power equal to 

or less than 145 horsepower’’ and 

another is ‘‘any combination of boilers 

with a cumulative maximum design 

heat input capacity of less than 10 

million Btu/hr.’’ The ADEQ explained 

in its 2012 NSR SIP submittal how the 

cumulative heat input or power rating 


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51See Appendix A to the 2012 NSR SIP submittal 

at 1570 and 1571. 

52EPA’s 2015 TSD at 25. 

53Section 4.3 of 2020 Minor NSR submittal at 13– 

14. 

54The commenters specifically identified 

‘‘modeling’’ as an example of the type of evidence 

to support this exemption. Modeling was not 

required to make this demonstration. 

55 In our 2015 NSR action, we approved of the 

ADEQ’s ‘‘permitting exemption thresholds’’ for 

each regulated pollutant, except PM2.5, and our 

approval of the thresholds was limited to their 

application in attainment areas. With today’s 

action, we are now also approving the thresholds 

as they apply to PM2.5 and nonattainment areas. 56 62 FR 27968 (May 22, 1997). 

for each category of equipment was 

determined by estimating the worst-case 

potential emissions for the category and 

ensuring that such emissions would be 

below the ADEQ’s permitting exemption 

thresholds.51 With this clarification, we 

approved of the ‘‘categorically exempt 

activities’’ in the 2015 NSR action.52 To 

illustrate this concept, the 2020 Minor 

NSR submittal also contains a sample 

calculation for a boiler burning No. 6 

fuel oil with a heat input rating of 10 

MMBtu/hr. The sample calculation 

shows that potential emissions of NOX

from such equipment would be 16.1 

tons per year and below the ADEQ’s 20 

tpy minor NSR permitting exemption 

threshold for NOX. Accordingly, the 

smaller fuel-burning equipment, rated 

less than 1 MMBtu/hr, that is exempt 

under ARS section 49–426(B) would 

have emissions well below the ADEQ’s 

approved permitting exemption 

thresholds, and therefore would not 

otherwise require a permit or 

registration under the ADEQ’s program. 

The ADEQ explains that the purpose of 

the exemption for categorically exempt 

activities is to allow such low-emitting 

small fuel-burning installations, which 

would not in any case require a permit, 

to avoid having to perform unnecessary 

emissions calculations.53

Given the rationale provided by the 

ADEQ, and our prior review and 

approval under 40 CFR 51.160(e) of the 

ADEQ’s exemption of ‘‘categorically 

exempt activities’’ under its minor NSR 

program, we disagree with the 

commenters that the ADEQ has not 

adequately justified the state law 

exemption.54 The ADEQ has 

demonstrated that fuel burning 

equipment rated less than 1 MMBtu/hr 

is equipment that falls within the 

existing SIP-approved category of 

‘‘categorically exempt activities,’’ and 

also that it is equipment that would 

otherwise not require a permit or 

registration compared to the ADEQ’s 

approved 55 permitting thresholds. In 

sum, the state law exemption for small 

fueling burning equipment has 

previously been determined by the EPA 

to be inconsequential to attainment and 

maintenance of the NAAQS, and the 

commenters have not provided 

information demonstrating why they 

believe this exemption is not protective 

of the NAAQS, or otherwise provided 

information that calls into question our 

previous approval of the ADEQ’s 

exemption for categorically exempt 

activities under 40 CFR 51.160(e). 

Comment: The ADEQ states that its 

NSR program applies to the areas of the 

State where the ADEQ has permitting 

jurisdiction (all counties in Arizona 

other than Maricopa, Pima, and Pinal, 

except where the ADEQ asserts 

jurisdiction). The commenters state that 

the ADEQ should explain whether the 

minor NSR programs in Maricopa, Pima, 

and Pinal counties are SIP-approved 

and meet all CAA requirements. To the 

extent they do not, the ADEQ should fix 

any deficiencies with the 2020 Minor 

NSR submittal. 

Response: As the commenters note, 

the 2020 Minor NSR submittal, and the 

requirements therein relating to the 

ADEQ’s minor NSR permitting program, 

are applicable only to those portions of 

the Arizona SIP where the ADEQ has 

minor NSR permitting jurisdiction. The 

EPA reviewed the ADEQ’s submitted 

SIP revision and determined that it 

complies with all relevant CAA 

requirements for approval into the 

Arizona SIP. In addition, this revision 

will correct several outstanding 

deficiencies in the ADEQ’s minor NSR 

program that were previously identified 

by the EPA. The commenters’ questions 

about the sufficiency of the minor NSR 

permitting programs for other areas and 

sources within Arizona that are within 

the jurisdiction of Maricopa, Pima, and 

Pinal counties, and which are not 

covered by ADEQ’s minor NSR program, 

are not germane to the EPA’s current SIP 

action on the 2020 Minor NSR 

submittal. The CAA does not require 

that the ADEQ (or the EPA) address all 

components of the minor NSR program 

implemented by all permitting 

authorities in Arizona in any particular 

SIP action. 

III. EPA Action 

No comments changed our assessment 

of our proposed action. Therefore, as 

authorized in section 110(k)(3) of the 

Act, the EPA is approving the ADEQ’s 

2019–20 NSR submittals, specifically 

including the 2020 Minor NSR 

submittal and the Ammonia PM2.5 NSR 

submittal. We find that the ADEQ has 

corrected all remaining deficiencies 

identified as the bases for our final 

limited disapproval of the ADEQ’s NSR 

program in our 2015 NSR action and the 

basis for our conditional approval of the 

ADEQ’s NNSR program in our 2018 

Major NSR action. Thus, the issues that 

formed the basis for our final limited 

disapproval in 2015 of the ADEQ’s 

minor NSR, PSD, and NNSR programs 

and our conditional approval in 2018 of 

the ADEQ’s NNSR program are now 

fully resolved. Our final action updates 

the ADEQ’s SIP-approved NSR program, 

corrects previously identified 

deficiencies, and recognizes that the 

ADEQ’s NSR program also satisfies the 

CAA visibility requirements in 40 CFR 

51.307. Additionally, the sanctions and 

sanctions clocks triggered by our 2016 

PM2.5 precursor action for the West 

Pinal and Nogales PM2.5 nonattainment 

areas will be permanently terminated on 

the effective date of this final approval 

action. 

This action approves the rules listed 

in Table 1 of this notice into the ADEQ 

portion of the Arizona SIP and removes 

or supersedes the rules listed in Table 

2 of this notice from the ADEQ portion 

of the Arizona SIP. We are also revising 

40 CFR 52.119 to remove the 

conditional approval of the State’s plan 

related to ammonia as a PM2.5 precursor, 

as we are now fully approving this 

component of the State’s plan. Finally, 

in conjunction with the EPA’s SIP 

approval of the ADEQ’s visibility 

program for sources subject to the 

ADEQ’s PSD and NNSR programs, we 

are revising 40 CFR 52.145(b) to remove 

the visibility FIP at 40 CFR 52.27, as 

well as the visibility FIP at 40 CFR 52.28 

for those stationary sources subject to 

the ADEQ’s permitting jurisdiction, as 

these FIPs are no longer applicable. 

IV. Incorporation by Reference 

In this rule, the EPA is finalizing 

regulatory text that includes 

incorporation by reference. In 

accordance with requirements of 1 CFR 

51.5, the EPA is finalizing the 

incorporation by reference of the ADEQ 

rules described in the amendments to 40 

CFR part 52 set forth below. Therefore, 

these materials have been approved by 

the EPA for inclusion in the SIP, have 

been incorporated by reference by the 

EPA into that plan, are fully federally 

enforceable under sections 110 and 113 

of the CAA as of the effective date of the 

final rulemaking of the EPA’s approval, 

and will be incorporated by reference in 

the next update to the SIP 

compilation.56 The EPA has made, and 

will continue to make, these documents 

available through https://

www.regulations.gov and at the EPA 

Region IX Office (please contact the 

person identified in the FOR FURTHER


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INFORMATION CONTACT section of this 

preamble for more information). 

Also in this document, as described in 

the amendments to 40 CFR part 52 set 

forth below, the EPA is removing 

provisions from the EPA-approved rules 

for the ADEQ portion of the Arizona 

SIP, which is incorporated by reference 

in accordance with the requirements of 

1 CFR part 51. 

V. Statutory and Executive Order 

Reviews 

Under the CAA, 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 Act. Accordingly, this proposed 

action merely proposes to approve state 

law as meeting federal requirements and 

does not impose additional 

requirements beyond those imposed by 

state law. For that reason, this proposed 

action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Orders 12866 (58 FR 51735, 

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

January 21, 2011); 

• Is not an Executive Order 13771 (82 

FR 9339, February 3, 2017) regulatory 

action because SIP approvals are 

exempted under Executive Order 12866; 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

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

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

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

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

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

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

section 12(d) of the National 

Technology Transfer and Advancement 

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

application of those requirements would 

be inconsistent with the CAA; 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). 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Carbon monoxide, 

Incorporation by reference, 

Intergovernmental relations, Nitrogen 

dioxide, Ozone, Particulate matter, 

Sulfur dioxide, Reporting and 

recordkeeping requirements, Volatile 

organic compounds. 

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

Dated: June 8, 2021. 

Deborah Jordan, 

Acting Regional Administrator, Region IX. 

Accordingly, 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 D—Arizona 

§ 52.119 [Amended] 

■ 2. In § 52.119, remove and reserve 

paragraph (a). 

■ 3. In § 52.120, paragraph (c), Table 2 

is amended: 

■ a. Under the heading ‘‘Title 9, Chapter 

3’’, by removing the center heading 

‘‘Article 2’’ and the entry for ‘‘R9–3– 

217, paragraph A’’; 

■ b. Under the heading ‘‘Title 18, 

Chapter 2, Article 1 (General)’’, by 

revising the entry for ‘‘R18–2–101 

(except 20)’’; 

■ c. Under heading ‘‘Title 18, Chapter 2, 

Article 3 (Permits and Permit 

Revisions)’’, by: 

■ i. Revising the entries for ‘‘R18–2– 

301,’’ ‘‘R18–2–302,’’ ‘‘R18–2–302.01,’’ 

‘‘R18–2–304,’’ ‘‘R18–2–306,’’ ‘‘R18–2– 

306.01’’; 

■ ii. Adding, in numerical order, entries 

for ‘‘R18–2–317,’ ‘‘R18–2–317.01,’’ and 

‘‘R18–2–317.02’’; and 

■ iii. Revising the entries for ‘‘R18–2– 

319,’’ ‘‘R18–2–320,’’ and ‘‘R18–2–334’’; 

and 

■ d. Under the heading ‘‘Title 18, 

Chapter 2, Article 4 (Permit 

Requirements for New Major Sources 

and Major Modifications to Existing 

Major Sources)’’, by revising the entry 

for ‘‘R18–2–406.’’ 

The additions and revisions read as 

follows: 

§ 52.120 Identification of plan. 

* * * * * 

(c) * * * 

TABLE 2—EPA-APPROVED ARIZONA REGULATIONS

State citation Title/subject State effective date EPA approval date Additional explanation 

*******

Article 1 (General) 

R18–2–101 (except 

20).

Definitions ......................................... February 1, 2020 ... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 


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Federal Register / Vol. 86, No. 114 / Wednesday, June 16, 2021 / Rules and Regulations 31939 

TABLE 2—EPA-APPROVED ARIZONA REGULATIONS—Continued 

State citation Title/subject State effective date EPA approval date Additional explanation 

*******

Article 3 (Permits and Permit Revisions) 

R18–2–301 ............ Definitions ......................................... February 1, 2020 ... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–302 ............ Applicability; Registration; Classes 

of Permits.

March 21, 2017 ..... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–302.01 ....... Source Registration Requirements .. February 1, 2020 ... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

* * * * * * * 

R18–2–304 ............ Permit Application Processing Procedures.February 1, 2020 ... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–306 ............ Permit Contents ................................ March 21, 2017 ..... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–306.01 ....... Permits Containing Voluntarily Accepted Emission Limitations and 

Standards.

March 21, 2017 ..... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

* * * * * * * 

R18–2–317 ............ Facility Changes Allowed Without 

Permit Revisions—Class I.

August 7, 2012 ...... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–317.01 ....... Facility Changes that Require a Permit Revision—Class II.August 7, 2012 ...... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–317.02 ....... Procedures for Certain Changes that 

Do Not Require a Permit Revision—Class II.

August 7, 2012 ...... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–319 ............ Minor Permit Revisions .................... March 21, 2017 ..... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

R18–2–320 ............ Significant Permit Revisions ............. March 21, 2017 ..... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

* * * * * * * 

R18–2–334 ............ Minor New Source Review ............... February 1, 2020 ... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

Article 4 (Permit Requirements for New Major Sources and Major Modifications to Existing Major Sources) 

*******

R18–2–406 ............ Permit Requirements for Sources 

Located in Attainment and 

Unclassifiable Areas.

February 1, 2020 ... [INSERT Federal Register 

CITATION], June 16, 2021.

Submitted on July 22, 2020. 

* * * * * * * 

* * * * * 

■ 4. In § 52.145, revise paragraph (b) to 

read as follows: 

§ 52.145 Visibility protection. 

* * * * * 

(b) Regulations for visibility new 

source review. The provisions of § 52.28 

are hereby incorporated and made part 

of the applicable plan for the State of 

Arizona only for those stationary 

sources under the permitting 

jurisdiction of the Pima County 

Department of Environmental Quality or 

the Maricopa County Air Quality 

Department. The provisions of § 52.28 

also remain the applicable plan for any 

Indian reservation lands, and any other 

area of Indian country where the EPA or 

an Indian tribe has demonstrated that a 

tribe has jurisdiction, located within the 

State of Arizona. 

* * * * * 

[FR Doc. 2021–12431 Filed 6–15–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 141 and 142 

[EPA–HQ–OW–2017–0300; FRL–10024–33– 

OW] 

RIN 2040–AG15 

National Primary Drinking Water 

Regulations: Lead and Copper Rule 

Revisions; Delay of Effective and 

Compliance Dates 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is delaying until 

December 16, 2021, the effective date of 

the National Primary Drinking Water 


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