Federal Register / Vol. 86, No. 150 / Monday, August 9, 2021 / Proposed Rules 43461 

1NDEP submitted the 2020 Ozone Maintenance 

Plan Revision electronically on September 30, 2020, 

as an attachment to a transmittal letter dated 

September 25, 2020. 

EPA-APPROVED MISSOURI REGULATIONS

Missouri citation Title State effective 

date EPA approval date Explanation 

Missouri Department of Natural Resources 

*******

Chapter 5—Air Quality Standards and Air Pollution Control Regulations for the St. Louis Metropolitan Area 

*******

10–5.540 ................. Control of Emissions From Batch Process Operations.7/30/2020 [Date of publication of the final rule in 

the Federal Register], [Federal Register citation of the final rule].

*******

* * * * * 

[FR Doc. 2021–16739 Filed 8–6–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R09–OAR–2021–0368; FRL–8716–01– 

R9 ] 

Air Plan Approval; Nevada; Revisions 

to Clark County Ozone Maintenance 

Plan 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing to approve a 

revision to the State of Nevada’s state 

implementation plan (SIP) for Clark 

County. The revision consists of an 

update to certain elements of the 

maintenance plan for the Clark County 

air quality planning area for the 1997 8- 

hour ozone national ambient air quality 

standards (NAAQS or ‘‘standards’’), 

including certain emissions inventories 

and motor vehicle emissions budgets. 

The EPA is proposing to approve the 

SIP revision because the Clark County 

ozone maintenance plan, as revised, 

continues to provide for maintenance of 

the 1997 ozone NAAQS and will not 

interfere with attainment or reasonable 

further progress of the other NAAQS, 

and the motor vehicle emissions 

budgets meet the applicable 

transportation conformity requirements. 

DATES: Comments must be received on 

or before September 8, 2021. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R09– 

OAR–2021–0368, at https://

www.regulations.gov. For comments 

submitted at Regulations.gov, follow the 

online instructions for submitting 

comments. Once submitted, comments 

cannot be edited or removed from 

Regulations.gov. The EPA may publish 

any comment received to its public 

docket. Do not submit electronically any 

information you consider to be 

Confidential Business Information (CBI) 

or other information whose disclosure is 

restricted by statute. Multimedia 

submissions (audio, video, etc.) must be 

accompanied by a written comment. 

The written comment is considered the 

official comment and should include 

discussion of all points you wish to 

make. The EPA will generally not 

consider comments or comment 

contents located outside of the primary 

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

other file sharing system). For 

additional submission methods, please 

contact the person identified in the FOR

FURTHER INFORMATION CONTACT section. 

For the full EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

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

commenting-epa-dockets. If you need 

assistance in a language other than 

English or if you are a person with 

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: 

Karina O’Connor, Air Planning Office 

(AIR–2), EPA Region IX, 75 Hawthorne 

Street, San Francisco, CA 94105; By 

phone: (775) 434–8176 or by email at 

oconnor.karina@epa.gov. 

SUPPLEMENTARY INFORMATION: 

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

or ‘‘our’’ refer to the EPA. 

Table of Contents 

I. What action is the EPA proposing? 

II. Background 

A. NAAQS, SIPs, Designations, and Clark 

County 

B. 2008 and 2015 Ozone NAAQS 

C. Transportation Conformity and the 2018 

Ozone Maintenance Plan Revision 

III. What did the State submit? 

IV. Procedural Requirements for Adoption 

and Submittal of SIP Revisions 

V. The EPA’s Evaluation of the 2020 Ozone 

Maintenance Plan Revision 

A. Emission Inventories 

B. Revised Motor Vehicle Emissions 

Budgets 

C. CAA Section 110(l) Evaluation 

VI. Proposed Action and Request for Public 

Comment 

VII. Statutory and Executive Order Reviews 

I. What action is the EPA proposing? 

Under section 110(k) of the Clean Air 

Act (‘‘Act’’ or CAA), the EPA is required 

to take action by approving, 

disapproving, or conditionally 

approving, in whole or in part, SIPs and 

SIP revisions submitted by the states. In 

today’s action, the EPA is proposing to 

approve a SIP revision titled ‘‘Revision 

to Motor Vehicle Emissions Budgets for 

the 1997 Ozone NAAQS, Clark County, 

Nevada’’ (August 2020) (herein, referred 

to as the ‘‘2020 Ozone Maintenance Plan 

Revision’’), submitted by the Nevada 

Division of Environmental Protection 

(NDEP) on September 30, 2020.1 The 

2020 Ozone Maintenance Plan Revision 

updates certain elements of the 

maintenance plan for Clark County for 

the 1997 ozone NAAQS, including 

certain emissions inventories and the 

motor vehicle emissions budgets 

(‘‘budgets’’ or MVEBs). The 2020 Ozone 

Maintenance Plan Revision was 

prepared in response to the EPA’s 

conditional approval of the ‘‘Revision to 

Motor Vehicle Emissions Budgets in 

Ozone Redesignation Request and 

Maintenance Plan: Clark County, 


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2 84 FR 44699 (August 27, 2019). 

3 40 CFR 93.118(f)(2)(v). 

4 Ground-level ozone pollution is formed from the 

reaction of volatile organic compounds (VOC) and 

oxides of nitrogen (NOX) in the presence of 

sunlight. These two pollutants, referred to as ozone 

precursors, are emitted by many types of sources, 

including on-and off-road motor vehicles and 

engines, power plants and industrial facilities, and 

smaller area sources such as lawn and garden 

equipment and paints. 

5 62 FR 38856 (July 18, 1997) and 40 CFR 50.10. 

6 69 FR 23858 (April 30, 2004) and 69 FR 55956 

(September 17, 2004). The Clark County ozone 

nonattainment area for the 1997 ozone NAAQS 

includes a significant portion of the unincorporated 

portions of central and southern Clark County, as 

well as the cities of Las Vegas, Henderson, North 

Las Vegas, and Boulder City. The ‘‘Subpart 1’’ 

classification meant that the area was subject solely 

to the general nonattainment area requirements 

under subpart 1 of part D (of title I) of the CAA 

rather than to the requirements under both subparts 

1 and the ozone-specific requirements under 

subpart 2. Several years later, in response to 

litigation over the designations for the 1997 ozone 

NAAQS, the EPA revised the classification of the 

Clark County ozone nonattainment area from 

‘‘Subpart 1’’ to ‘‘Subpart 2/Marginal.’’ 77 FR 28424 

(May 14, 2012). 

7 76 FR 17343 (March 29, 2011). 

8 In the State of Nevada, NDEP is the Governor’s 

designee for adoption and submittal of SIPs and SIP 

revisions to the EPA. In Clark County, the Clark 

County DES is responsible under state law for 

regulation of most types of stationary sources 

within the county and for development of local air 

quality plans. Once adopted by the Clark County 

Board of County Commissioners, such county plans 

are forwarded to NDEP for adoption and submittal 

to the EPA as revisions to the Nevada SIP. 

9Under the EPA’s transportation conformity rule, 

at 40 CFR 93.101, budgets are defined as the 

portions of the total allowable emissions that are 

allocated to on-road vehicle use that, together with 

emissions from other sources in the area, will 

provide for RFP, attainment or maintenance. The 

budgets serve as a ceiling on emissions from an 

area’s planned transportation system. 

10 78 FR 1149 (January 8, 2013). 

11 2011 Ozone Maintenance Plan, 6–11. 

12Under EPA regulations at 40 CFR 50.10 and 

appendix I, the 1997 ozone NAAQS is attained at 

a site when the 3-year average of the annual fourthhighest daily maximum 8-hour average ozone 

concentration is less than or equal to 0.08 ppm. 

This 3-year average is referred to as the design 

value. When the design value is less than or equal 

to 0.084 ppm (based on the rounding convention in 

40 CFR part 50, appendix I) at each monitoring site 

within the area, then the area is meeting the 1997 

ozone NAAQS. The highest design value among the 

various ozone monitoring sites represents the 

design value for the area. 

Nevada’’ (October 2018) (herein, 

referred to as the ‘‘2018 Ozone 

Maintenance Plan Revision’’).2 The 

2020 Ozone Maintenance Plan Revision 

revises certain budgets from the 2018 

Ozone Maintenance Plan Revision to 

prevent interference with reasonable 

further progress or attainment of the 

2008 and 2015 ozone NAAQS. If the 

EPA takes final action to approve the 

2020 Ozone Maintenance Plan Revision, 

the revised budgets will replace Clark 

County’s existing budgets for the plan 

horizon year (2022) for the 1997 ozone 

NAAQS. At that time, the previouslyapproved budgets would no longer be 

applicable for transportation conformity 

purposes, and the revised budgets 

would need to be used beginning on the 

publication date of the EPA’s final 

approval in the Federal Register.3

II. Background 

A. NAAQS, SIPs, Designations, and 

Clark County 

Under section 109 of the CAA, the 

EPA promulgates NAAQS for pervasive 

air pollutants, such as ozone. The 

NAAQS are concentration levels that, 

the attainment and maintenance of 

which, the EPA has determined to be 

requisite to protect public health and 

welfare. Under CAA section 107(d), the 

EPA must designate all areas of the 

country as attainment, nonattainment or 

unclassifiable for new or revised 

NAAQS. Section 110 of the CAA 

requires states to develop and submit 

SIPs to implement, maintain, and 

enforce the NAAQS. Once a 

nonattainment area has attained the 

NAAQS, the state may request 

redesignation of the area from 

nonattainment to attainment, and the 

EPA grants such requests if the criteria 

in CAA section 107(d)(3)(E) are met, 

including the approval of a maintenance 

plan (under CAA section 175A) that 

demonstrates how the area will 

maintain the NAAQS for at least 10 

years after the redesignation. Such 

former nonattainment areas that have 

been redesignated to attainment are 

referred to as ‘‘maintenance areas.’’ 

In 1997, the EPA replaced the 1-hour 

ozone 4 NAAQS at a level of 0.12 parts 

per million (ppm) with an 8-hour ozone 

NAAQS at a level of 0.08 ppm (herein, 

the ‘‘1997 ozone NAAQS’’).5 In 2004, 

the EPA designated a portion of Clark 

County as a ‘‘Subpart 1’’ nonattainment 

area for the 1997 ozone NAAQS.6 In 

2011, the EPA determined that the Clark 

County 8-hour ozone nonattainment 

area had attained the 1997 8-hour ozone 

NAAQS, based on complete, qualityassured, and certified ambient air 

monitoring data that showed the area 

monitored attainment of the 1997 ozone 

NAAQS for the 2007–2009 monitoring 

period.7

In light of ambient monitoring data 

showing that the Clark County ozone 

nonattainment area had attained the 

1997 ozone NAAQS, NDEP submitted a 

request to redesignate the Clark County 

ozone area from nonattainment to 

attainment and submitted the ‘‘Ozone 

Redesignation Request and Maintenance 

Plan, Clark County, Nevada (March 

2011)’’ (herein, the ‘‘2011 Ozone 

Maintenance Plan’’) to the EPA for 

approval as a revision to the Clark 

County portion of the Nevada SIP. 

Prepared by the Clark County 

Department of Air Quality and 

Environmental Management (currently 

named ‘‘Department of Environment 

and Sustainability’’ (DES)),8 the 2011 

Ozone Maintenance Plan includes the 

required elements for maintenance 

plans, including an attainment 

inventory, maintenance demonstration, 

monitoring network, verification of 

continued attainment, contingency plan, 

and budgets.9 The 2011 Ozone 

Maintenance Plan demonstrates 

maintenance of the 1997 ozone NAAQS 

through year 2022 by reference to 

emissions inventories developed for 

years 2015 and 2022 that show 

emissions of volatile organic 

compounds (VOC) and oxides of 

nitrogen (NOX) in those years would not 

exceed the level of the corresponding 

emissions of the 2008 attainment 

inventory. The 2011 Ozone 

Maintenance Plan established budgets 

for NOX and VOC for years 2008, 2015, 

and 2022. The budgets were derived 

from the on-road motor vehicle 

emissions estimates prepared using the 

EPA’s then-current on-road vehicle 

emissions model, MOBILE6.2, and the 

most recent vehicle mix and activity 

data available from the Regional 

Transportation Commission of Southern 

Nevada. In 2013, the EPA approved the 

2011 Ozone Maintenance Plan and 

redesignated the Clark County ozone 

nonattainment area to attainment for the 

1997 ozone NAAQS.10

Through adoption of the 2011 Ozone 

Maintenance Plan, Clark County DES 

committed to maintaining an ambient 

air quality monitoring network to verify 

the continued attainment of the 1997 

ozone NAAQS in the Clark County 

ozone maintenance area.11 At the 

present time, 10 monitoring sites 

continuously monitor ambient 

concentrations of ozone within the 

maintenance area. Since 2008, i.e., the 

year used for the attainment inventory 

in the 2011 Ozone Maintenance Plan, 

ambient ozone concentrations in Clark 

County have decreased. As shown in 

Table 1, 8-hour ozone design values 

have decreased from 0.082 ppm in 2008 

to 0.073 ppm in 2019.12 In more recent 

years, the design value has remained 

relatively steady, varying little from year 

to year. Table 1 shows that Clark County 

has maintained the 1997 ozone NAAQS 

through the first seven years (2013 

through 2019) of the first maintenance 

period. 


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13 73 FR 16436 (March 27, 2008) and 40 CFR 

50.15. 

14 77 FR 30088 (May 21, 2012). Hydrographic 

areas are those that are shown on the State of 

Nevada Division of Water Resources’ map titled 

‘‘Water Resources and Inter-basin Flows’’ 

(September 1971). 

15 80 FR 65292 (October 26, 2015) and 40 CFR 

50.19. 

16 83 FR 25776 (June 4, 2018). 

17CAA section 176(c)(5). 

18The EPA’s guidance ‘‘Transportation 

Conformity Guidance for the South Coast II Court 

Decision’’ (November 2018, EPA–20–B–18–050), 

explains that while conformity requirements 

continue to apply for the revoked 1997 ozone 

NAAQS, conformity can be demonstrated without 

a regional emissions analysis for the 1997 ozone 

standard. 19 84 FR 44699 (August 27, 2019). 

TABLE 1—EIGHT-HOUR OZONE DESIGN VALUES FOR THE CLARK

COUNTY OZONE MAINTENANCE

AREA, 2008–2020 

Year 

Design 

value 

(ppm) 

2008 ...................................... 0.082 

2009 ...................................... 0.078 

2010 ...................................... 0.076 

2011 ...................................... 0.075 

2012 ...................................... 0.076 

2013 ...................................... 0.077 

2014 ...................................... 0.078 

2015 ...................................... 0.075 

2016 ...................................... 0.075 

2017 ...................................... 0.074 

2018 ...................................... 0.076 

2019 ...................................... 0.073 

2020 ...................................... 0.074 

Source: The EPA’s 2017 and 2020 Ozone 

Design Values Reports at https://

www.epa.gov/air-trends/air-quality-design-values#report. Note that design values reported 

for a given year reflect data from that year and 

the two previous years, e.g., the design value 

for 2008 reflects data from 2006–2008. 

B. 2008 and 2015 Ozone NAAQS 

In 2008, the EPA lowered the ozone 

NAAQS to a level of 0.075 ppm, 8-hour 

average (herein, the ‘‘2008 ozone 

NAAQS’’),13 and in 2012, the EPA 

designated all of the hydrographic areas 

within the State of Nevada as 

‘‘Unclassifiable/Attainment’’ for the 

2008 ozone NAAQS.14 Because all the 

hydrographic areas located entirely, or 

partially, within Clark County were 

designated as unclassifiable/attainment 

for the 2008 ozone NAAQS, no 

reasonable further progress (RFP) or 

attainment SIP revision was required for 

any portion of the county. 

In 2015, the EPA further lowered the 

ozone NAAQS to 0.070 ppm, 8-hour 

average (herein the ‘‘2015 ozone 

NAAQS’’).15 In 2018, the EPA 

designated the Las Vegas Valley portion 

of Clark County as a ‘‘Marginal’’ 

nonattainment area for the 2015 ozone 

NAAQS, effective August 3, 2018.16 The 

nonattainment area designation for Las 

Vegas Valley for the 2015 ozone NAAQS 

triggered the requirement for certain SIP 

revisions under CAA section 182(a) and 

the EPA’s related SIP Requirements 

Rule promulgated at 40 CFR part 51, 

subpart CC. 

C. Transportation Conformity and the 

2018 Ozone Maintenance Plan Revision 

The EPA’s transportation conformity 

rule at 40 CFR part 93, subpart A 

establishes the criteria and procedures 

that metropolitan planning 

organizations (MPOs) and the U.S. 

Department of Transportation (DOT) 

must use to determine whether 

transportation activities conform to the 

SIP. Transportation conformity applies 

to areas that are designated 

nonattainment and those former 

nonattainment areas that have been 

redesignated to attainment and have a 

CAA section 175A maintenance plan 

(‘‘maintenance areas’’), but does not 

apply to areas designated as attainment 

or unclassifiable.17 In Clark County, the 

area’s MPO, the Regional Transportation 

Commission of Southern Nevada (RTC), 

and DOT are the relevant transportation 

agencies that must determine the 

conformity of transportation plans and 

transportation improvement plans 

(TIPs) within Clark County. 

Under our transportation conformity 

rule, the latest approved or adequate 

emissions budgets for a previous ozone 

NAAQS (i.e., the 2008 or the 1997 ozone 

NAAQS) must be used in conformity 

determinations for the 2015 ozone 

NAAQS until emission budgets are 

established and found adequate or are 

approved for the 2015 ozone NAAQS. 

Because the latest approved or adequate 

emissions budgets for a previous ozone 

NAAQS for Clark County are the 

approved budgets for the 1997 8-hour 

ozone NAAQS, the RTC and DOT must 

use these budgets for conformity 

determinations for the 2015 ozone 

NAAQS 18 until they are replaced by 

updated budgets for the 2015 ozone 

NAAQS. 

In 2018, NDEP submitted the 2018 

Ozone Maintenance Plan Revision as a 

revision to the Clark County portion of 

the Nevada SIP. The 2018 Ozone 

Maintenance Plan Revision includes 

revisions to the attainment inventory, 

the maintenance demonstration, and 

budgets in the 2011 Ozone Maintenance 

Plan to reflect updated emissions 

models, vehicle mix and speed data, 

and transportation activity projections. 

The 2018 Ozone Maintenance Plan 

Revision revised the budgets for NOX

and VOC for years 2008, 2015, and 

2022. The revised budgets were derived 

from the on-road motor vehicle 

emissions estimates prepared using the 

most recent version of the EPA’s onroad vehicle emissions model available 

at the time (MOVES2014a) and updated 

planning variables (e.g., vehicle miles 

traveled projections and population 

forecasts) from the RTC. The 2018 

Ozone Maintenance Plan Revision was 

developed so that the RTC and DOT 

would have updated budgets available 

to use for transportation conformity 

determinations with respect to the 2015 

ozone NAAQS until budgets developed 

specifically for the 2015 ozone NAAQS 

are adopted and found to be adequate or 

approved. In 2019, the EPA 

conditionally approved the 2018 Ozone 

Maintenance Plan Revision as a revision 

of the Clark County portion of the 

Nevada SIP.19

In so doing, we found that the 2011 

Ozone Maintenance Plan, as revised by 

the updated attainment inventory and 

maintenance demonstration in the 2018 

Ozone Maintenance Plan Revision, 

continues to provide for maintenance of 

the 1997 ozone NAAQS, and upon 

fulfillment of the commitments made by 

NDEP and Clark County DES to reduce 

the safety margin allocations for the 

budgets, will not interfere with RFP or 

attainment of the other NAAQS in Clark 

County. In conditionally approving the 

2018 Ozone Maintenance Plan Revision, 

the EPA also found adequate and 

conditionally approved the updated 

NOX and VOC budgets for 2008, 2015, 

and 2022 for the 1997 ozone NAAQS 

based on our conclusion that the 

updated budgets meet the applicable 

transportation conformity requirements. 

The approval was conditional because it 

is based on commitments by Clark 

County DES and NDEP to submit an 

additional SIP revision to reduce the 

safety margin allocations for the budgets 

in the 2018 Ozone Maintenance Plan 

Revision within one year of this final 

conditional approval. 

In September 2020, NDEP submitted 

the 2020 Ozone Maintenance Plan 

Revision to the EPA in fulfillment of the 

commitments made by Clark County 

DES and NDEP in connection with the 

EPA’s conditional approval of the 2018 

Ozone Maintenance Plan Revision. The 

2020 Ozone Maintenance Plan Revision 

is the subject to today’s proposed action. 

III. What did the State submit? 

On August 18, 2020, the Clark County 

Board of County Commissioners 

adopted the 2020 Ozone Maintenance 

Plan Revision and forwarded the plan to 

NDEP for adoption and submittal to the 


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20Clark County Board of County Commissioners 

Meeting, Meeting Summary, October 16, 2018, 14 

and 15. 

21Letter dated September 25, 2020, from Greg 

Lovato, Administrator, NDEP to Elizabeth Adams, 

Director, Air Division, EPA Region IX, (submitted 

electronically on September 30, 2020 with 

enclosures). 

22Appendix B provides evidence that reasonable 

notice of a public hearing was provided to the 

public and that a public hearing was conducted 

prior to adoption. Specifically, notice of the 

availability of, and opening of a 30-day comment 

period on the draft ozone maintenance plan 

revision was published on June 25, 2020, on the 

County’s webpage. No comments were submitted. 23The NEI is a comprehensive and detailed 

estimate of air emissions of criteria pollutants, 

criteria precursors, and hazardous air pollutants 

from air emissions sources. The NEI is released 

every three years based primarily upon data 

provided by State, Local, and Tribal air agencies for 

sources in their jurisdictions and supplemented by 

data developed by the EPA. 

24 In Clark County, Nevada, the highest ambient 

ozone concentrations generally occur during the 

months of the year when the highest temperatures 

occur—typically from May through September. For 

SIP planning purposes, Clark County has selected 

weekdays in the month of July as the basis to 

estimate typical summertime weekday emissions. 

25The 2020 Ozone Maintenance Plan Revision 

uses the term, ‘‘point sources,’’ to refer to those 

stationary source facilities that are required to 

report their emissions to Clark County DES or 

NDEP. 

26The 2020 Ozone Maintenance Plan Revision 

uses the term, ‘‘nonpoint sources,’’ to refer to those 

stationary and area sources that fall below point 

source reporting levels and that are too numerous 

or small to identify individually. 

27For the 2020 Ozone Maintenance Plan 

Revision, ‘‘biogenic sources’’ include the following: 

Agricultural crops; lawn grass; forests that produce 

isoprene, monoterpene, alpha-pinene, and other 

VOC emissions; and soils that generate trace 

amounts of NOX. 

28See Table 2–1 in the 2020 Ozone Maintenance 

Plan Revision. 

EPA.20 On September 30, 2020, NDEP 

submitted the 2020 Ozone Maintenance 

Plan Revision to the EPA as a revision 

to the Clark County portion of the 

Nevada SIP.21 The 2020 Ozone 

Maintenance Plan Revision also 

includes a technical support document 

(appendix A of the plan revision) and 

documentation of the public review 

process (appendix B of the plan 

revision). 

Through the 2020 Ozone Maintenance 

Plan Revision, Clark County DES is 

updating the emissions projections for 

the ozone maintenance plan horizon 

year of 2022 based on the latest 

available emissions models, vehicle mix 

and speed data, and transportation 

activity projections and is revising the 

budgets for 2022 to reflect the updated 

projections for that year and to include 

a reduced safety margin compared to the 

corresponding budgets from the 2018 

Ozone Maintenance Plan Revision. The 

2020 Ozone Maintenance Plan Revision 

also presents a new emissions inventory 

for year 2017 that provides the basis to 

evaluate the new budgets with respect 

to continued attainment of the 2008 

ozone NAAQS and progress towards 

attainment of the 2015 ozone NAAQS in 

Las Vegas Valley. 

IV. Procedural Requirements for 

Adoption and Submittal of SIP 

Revisions 

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

of the CAA require a state to provide 

reasonable public notice and 

opportunity for public hearing prior to 

the adoption and submittal of a SIP or 

SIP revision. To meet this requirement, 

every SIP submittal should include 

evidence that adequate public notice 

was given and an opportunity for a 

public hearing was provided consistent 

with the EPA’s implementing 

regulations in 40 CFR 51.102. 

The Clark County Board of County 

Commissioners and NDEP have satisfied 

applicable statutory and regulatory 

requirements for reasonable public 

notice and public hearing prior to 

adoption and submittal of the 2020 

Ozone Maintenance Plan Revision. In 

the September 30, 2020 SIP submittal,22

Clark County DES provided evidence of 

the required public notice and 

opportunity for public comment prior to 

the August 18, 2020 public hearing and 

adoption of the 2020 Ozone 

Maintenance Plan Revision. Therefore, 

we find that the submittal of the 2020 

Ozone Maintenance Plan Revision 

meets the procedural requirements for 

public notice and hearing in CAA 

sections 110(a) and 110(l) and 40 CFR 

51.102. 

V. The EPA’s Evaluation of the 2020 

Ozone Maintenance Plan Revision 

Clark County DES and NDEP 

submitted the 2020 Ozone Maintenance 

Plan Revision to fulfill commitments 

made in connection with the EPA’s 

conditional approval of the 2018 Ozone 

Maintenance Plan Revision to reduce 

the safety margin allocations in the 

budgets to ensure that the Clark County 

ozone SIP will not interfere with RFP or 

attainment of the 2008 and 2015 ozone 

NAAQS consistent with CAA section 

110(l). As described further below, we 

have reviewed the 2020 Ozone 

Maintenance Plan Revision for 

compliance with the relevant 

requirements for maintenance plans 

under CAA section 175A and for 

noninterference under CAA section 

110(l), and we have evaluated the 

budgets in the 2020 Ozone Maintenance 

Plan Revision for compliance with the 

budget adequacy criteria in 40 CFR 

93.118(e). 

A. Emissions Inventories 

The 2020 Ozone Maintenance Plan 

Revision includes inventories of 

emissions of ozone precursors (VOC and 

NOX) for years 2017 and 2022. The 2017 

inventory provides estimates of actual 

emissions that occurred in that year. 

Clark County DES selected 2017 as the 

base year for the 2020 Ozone 

Maintenance Plan Revision for the 

following reasons: It is the most recent 

year for which National Emissions 

Inventory 23 (NEI) emissions estimates 

were available at the time the plan was 

being developed; it is an attainment year 

for the 2008 ozone NAAQS; and it is the 

base year for SIP planning purposes for 

the 2015 ozone NAAQS. Clark County 

DES used the 2017 inventory to revise 

the 2022 emissions inventory from the 

2018 Ozone Maintenance Plan Revision 

based on the latest methods and 

planning assumptions. 

As a general matter, base year 

emissions inventories must be (1) 

consistent with the EPA’s most recent 

guidance on emissions inventories 

available at the time, (2) comprehensive, 

including emissions from stationary 

point sources, area sources, nonroad 

mobile sources, and on-road mobile 

sources, and (3) based on actual ‘‘ozone 

season data’’ (i.e., summertime) 

emissions.24

The 2017 year inventory in the 2020 

Ozone Maintenance Plan Revision is 

comprehensive in that it includes 

estimates of summertime average 

weekday VOC and NOX emissions from 

all of the relevant source categories, 

which the plan divides among point 

sources,25 nonpoint sources,26

commercial aviation, federal aviation 

(i.e., Nellis Air Force Base), on-road 

mobile, nonroad mobile, and biogenic 27

sources.28 For comparison, the 2018 

Ozone Maintenance Plan Revision did 

not include a 2017 inventory, but 

emissions for 2017 can be interpolated 

from 2015 and 2022 emissions. 

Appendix A to the 2020 Ozone 

Maintenance Plan Revision contains 

source-specific descriptions of emission 

calculation procedures and sources of 

input data used for the update. 

Table 2 below compares the 2017 

inventory from the 2020 Ozone 

Maintenance Plan Revision with the 

corresponding interpolated inventory 

from the 2018 Ozone Maintenance Plan 

Revision. As shown in Table 2, the 

change in the 2017 inventory in the 

2020 Ozone Maintenance Plan Revision 

is primarily due to the update to the onroad mobile source category and the 

nonroad source category as well as a 

change in the methodology for biogenic 

emissions. 


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29 2020 Ozone Maintenance Plan Revision, 

Appendix A, 4–12. 

30https://www.epa.gov/air-emissions-modeling/ 

biogenic-emission-inventory-system-beis. 

31 2011 Ozone Maintenance Plan, 6–4. 

32 2020 Ozone Maintenance Plan Revision, 14. 

TABLE 2—2017 CLARK COUNTY OZONE PRECURSOR EMISSION INVENTORY

[County-wide, average summer weekday, tons per day] 

Source category 

NOX emissions VOC emissions 

2020 Ozone 

maintenance 

plan revision 

2018 Ozone 

maintenance 

plan revision 

2020 Ozone 

maintenance 

plan revision 

2018 Ozone 

maintenance 

plan revision 

Point source ..................................................................................................... 12.40 11.79 2.95 2.51 

Nonpoint source ............................................................................................... 7.651 5.68 62.56 59.94 

Commercial aviation ........................................................................................ 11.47 13.38 1.73 2.75 

Federal aviation ............................................................................................... 0.50 1.77 0.24 1.04 

On-road mobile ................................................................................................ 46.96 53.65 29.47 28.49 

Nonroad mobile ............................................................................................... 37.45 24.78 28.25 30.36 

Biogenic ........................................................................................................... 2.43 5.00 362.61 132.00 

Total .......................................................................................................... 118.86 116.06 487.81 257.09 

Sources: 2018 Ozone Maintenance Plan Revision, interpolated values from Tables 2–1 and 2–2; 2020 Ozone Maintenance Plan Revision, Tables 2–1 and 2–2. 

With respect to on-road mobile source 

emissions, Clark County DES updated 

the emissions estimates using 

MOVES2014b, RTC travel demand 

modeling, and highway performance 

monitoring system data from the Nevada 

Department of Transportation.29 Clark 

County DES also selected the inventory 

mode, rather than the emission rate 

mode used in the 2018 Ozone 

Maintenance Plan Revision, with 

MOVES2014b emissions factors and 

projected emissions for 2022 from 2017 

rather than 2015. Generally, on-road 

mobile source emissions estimates made 

using MOVES2014b are similar to 

MOVES2014a. With respect to nonroad 

emissions sources, the change in the 

2017 emissions inventory is largely due 

to the use of the nonroad module of 

MOVES2014b that was released in 

August 2018. Clark County DES used 

default estimates from MOVES2014b for 

Clark County and the most significant 

changes were in the two largest sectors: 

construction and lawn/garden, which 

increased and decreased, respectively. 

Overall, nonroad emissions are higher 

for NOX but lower for VOC using 

MOVES2014b compared to using the 

nonroad module of MOVES2014a. 

Biogenic emissions for Clark County 

were developed using the EPA’s 

Biogenic Emission Inventory System 30

(BEIS) version 3.61, which replaced the 

Emissions of Gasses and Aerosols from 

Nature (MEGAN) model used by Clark 

County DES for the 2011 Ozone 

Maintenance Plan 31 and the 2018 

Ozone Maintenance Plan Revision. The 

BEIS model allows for interactions 

between air quality and meteorology. In 

2017, the EPA updated the BEIS v3.61 

to include the biogenic emissions 

landcover database version 5 (BELD5) 

and the newer version of the forest 

inventory and analysis version 8.0. This 

updated model improved the biogenic 

VOC emissions estimates. Clark County 

DES used the updated BEIS model, 

which is part of SMOKE 4.7 (Sparse 

Matrix Operator Kerner Emissions) 

model, to generate the biogenic 

emissions for Clark County.32 The 

results show a slight decrease in NOX

and large increase in VOC biogenic 

emissions relative to the corresponding 

emissions estimates from the 2011 

Ozone Maintenance Plan and 2018 

Ozone Maintenance Plan Revision. 

Based on our review of the emissions 

inventories (and related documentation) 

from the 2020 Ozone Maintenance Plan 

Revision, we find that the inventories 

for 2017 are comprehensive, that the 

methods and assumptions used by Clark 

County DES to develop the 2017 

emission inventory are reasonable, and 

that the inventories reasonably estimate 

actual ozone season emissions in 2017. 

Moreover, we find that the 2017 

emissions inventories in the plan reflect 

the latest planning assumptions and 

emissions models available at the time 

the 2020 Ozone Maintenance Plan 

Revision was developed. 

To provide the basis for the 

comparison of future emissions with the 

updated 2017 emissions, Clark County 

DES updated the 2022 emissions 

inventories using the same approaches 

as described above for the 2017 

emissions inventory. Clark County DES 

allocated the same amount of emissions 

reductions credits (ERCs), for use in 

connection with the new major 

stationary source permitting program, 

for 2022 as had been allocated for that 

year in the 2018 Ozone Maintenance 

Plan Revision. With respect to 

transportation conformity safety 

margins, as described further in section 

V.B of this document, the Clark County 

DES significantly reduced the safety 

margins that had been included in 

budgets for the 2018 Ozone 

Maintenance Plan Revision. Table 3 

below compares the NOX and VOC 

emissions inventories, respectively, for 

2022 from the 2020 Ozone Maintenance 

Plan Revision with the corresponding 

values from the 2018 Ozone 

Maintenance Plan Revision. 

TABLE 3—2022 CLARK COUNTY OZONE PRECURSOR EMISSION INVENTORY

[County-wide, average summer weekday, tons per day] 

Source category 

NOX emissions VOC emissions 

2020 Ozone 

maintenance 

plan revision 

2018 Ozone 

maintenance 

plan revision 

2020 Ozone 

maintenance 

plan revision 

2018 Ozone 

maintenance 

plan revision 

Point source ..................................................................................................... 12.09 12.26 3.12 2.72 


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33 Key references used by Clark County DES 

include Eastern Research Group’s ‘‘Clark County 

On-Road Vehicle Classification Study,’’ final report, 

June 29, 2018, and the Coordinating Research 

Council’s ‘‘Improvement of Default Inputs for 

MOVES and SMOKE–MOVES, final report, 

February 2017. 

34 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more 

information on the transportation conformity 

requirements and applicable policies on budgets, 

please visit our transportation conformity website 

at: http://www.epa.gov/otaq/stateresources/ 

transconf/index.htm. 35 40 CFR 93.118(f)(2). 36Under the transportation conformity 

regulations, the EPA may review the adequacy of 

submitted motor vehicle emission budgets 

simultaneously with the EPA’s approval or 

disapproval of the submitted implementation plan. 

40 CFR 93.118(f)(2). 37The 2020 Ozone Maintenance Plan Revision 

does not revise the 2015 budgets from the 2018 

Ozone Maintenance Plan Revision that also 

included large safety margins; however, we note 

that, given the passage of time, the 2015 budgets 

from the 2018 Ozone Maintenance Plan Revision 

will no longer be used for conformity 

determinations and thus the failure to reduce the 

safety margins of the 2015 budgets in the 2018 

Ozone Maintenance Plan Revision is acceptable. 

TABLE 3—2022 CLARK COUNTY OZONE PRECURSOR EMISSION INVENTORY—Continued 

[County-wide, average summer weekday, tons per day] 

Source category 

NOX emissions VOC emissions 

2020 Ozone 

maintenance 

plan revision 

2018 Ozone 

maintenance 

plan revision 

2020 Ozone 

maintenance 

plan revision 

2018 Ozone 

maintenance 

plan revision 

Nonpoint source ............................................................................................... 7.57 5.04 62.58 59.49 

Commercial aviation ........................................................................................ 13.08 17.42 1.73 2.95 

Federal aviation ............................................................................................... 1.97 2.26 0.82 0.95 

On-road mobile ................................................................................................ 29.16 27.02 20.92 17.12 

Nonroad mobile ............................................................................................... 24.93 17.50 26.71 28.52 

Biogenic ........................................................................................................... 2.43 5.00 362.61 132.00 

Emission reduction credits ............................................................................... 22.23 22.23 0.43 0.43 

Transportation conformity safety margins ....................................................... 3.00 59.72 3.00 35.84 

Total .......................................................................................................... 116.46 168.45 484.92 280.02 

Sources: 2018 Ozone Maintenance Plan Revision, Tables 2–1, 2–2 and 3–1; 2020 Ozone Maintenance Plan Revision, Tables 2–1, 2–2 and 3– 

1. 

As shown in Table 3, emissions for 

2022 in the 2020 Ozone Maintenance 

Plan Revision are similar to the 

corresponding emissions in the 2018 

Ozone Maintenance Plan Revision 

except for biogenic emissions. Similar to 

the comparison of the emission 

inventories for the year 2017, 

differences are again primarily due to 

the updates to the on-road mobile 

source category, the nonroad source 

category, and the change in the 

methodology for biogenic emissions. 

The on-road mobile source emission 

estimates in the 2020 Ozone 

Maintenance Plan Revision reflect the 

most recent published data concerning 

vehicle registration data, vehicle miles 

traveled (VMT) temporal distribution, 

VMT mix profiles, vehicle speeds, and 

travel demand forecasts from RTC.33

Based on our review of the methods, 

assumptions, and data sources, as 

described in Appendix A to the 2020 

Ozone Maintenance Plan Revision, we 

find that the Clark County DES 

estimates for 2017 and 2022 for the 

various source categories to be based on 

the best available emissions models and 

data sources, and thus to provide a 

reasonable basis upon which to evaluate 

whether the area will continue to 

maintain the 1997 ozone NAAQS 

through 2022 and whether the revised 

budgets for 2022 in the 2020 Ozone 

Maintenance Plan Revision would 

interfere with RFP or attainment of the 

2008 and 2015 ozone NAAQS. 

B. Revised Motor Vehicle Emissions 

Budgets 

Section 176(c) of the CAA requires 

federal actions in nonattainment and 

maintenance areas to conform to the 

SIP’s goals of eliminating or reducing 

the severity and number of violations of 

the NAAQS and achieving timely 

attainment of the standards. Conformity 

to the SIP’s goals means that such 

actions will not: (1) Cause or contribute 

to violations of a NAAQS, (2) worsen 

the severity of an existing violation, or 

(3) delay timely attainment of any 

NAAQS or any interim milestone. 

Under the transportation conformity 

rule, MPOs in nonattainment and 

maintenance areas coordinate with state 

and local air quality and transportation 

agencies, the EPA, the Federal Highway 

Administration, and the Federal Transit 

Administration to demonstrate that an 

area’s regional transportation plans and 

TIPs conform to the applicable SIP. This 

demonstration is typically done by 

showing that estimated emissions from 

existing and planned highway and 

transit systems are less than or equal to 

the budgets contained in all control 

strategy or maintenance SIPs. Budgets 

are generally established for specific 

years and specific pollutants or 

precursors. Ozone maintenance plans 

should identify budgets for on-road 

emissions of ozone precursors (NOX and 

VOC) in the area for the last year of the 

maintenance period. Budgets may also 

be specified for additional years during 

the maintenance period. 

For budgets to be approvable, they 

must meet the EPA’s adequacy criteria 

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

comply with all pertinent SIP 

requirements. With respect to 

maintenance plans, to meet these 

requirements, the budgets must be 

consistent with the maintenance plan 

and reflect all the motor vehicle control 

measures contained in the maintenance 

demonstration.34 The EPA’s process for 

determining adequacy of a budget 

consists of three basic steps: (1) 

Providing public notification of a SIP 

submission; (2) providing the public the 

opportunity to comment on the budget 

during a public comment period; and, 

(3) making a finding of adequacy or 

inadequacy.35 We will complete the 

adequacy review of the budgets in the 

2020 Ozone Maintenance Plan Revision 

concurrent with our final action on the 

2020 Ozone Maintenance Plan Revision. 

The EPA is not required under its 

transportation conformity rule to find 

budgets adequate prior to proposing 

approval of them.36

The 2020 Ozone Maintenance Plan 

Revision includes revised budgets for 

VOC and NOX for the last year of the 

initial maintenance period, i.e., 2022.37

The revised budgets from the 2020 

Ozone Maintenance Plan Revision are 

shown in Table 4 below and compared 

with the corresponding budgets from 

the approved 2018 Ozone Maintenance 


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38 In this context, ‘‘safety margin’’ means the 

amount by which the total projected emissions from 

all sources of a given pollutant are less than the 

total emissions that would satisfy the applicable 

requirements for reasonable further progress, 

attainment or maintenance. With respect to the 

2020 Ozone Maintenance Plan Revision, the safety 

margin is the difference between the projected 

emissions in 2022 of NOX and VOC and the actual 

emissions of NOX and VOC in the 2008 attainment 

year as updated in the 2018 Ozone Maintenance 

Plan Revision. The anthropogenic emissions (i.e., 

excluding biogenic emissions) of NOX and VOC in 

2008 were approximately 178 tons per day (tpd) 

and 157 tpd, respectively. The 2020 Ozone 

Maintenance Plan Revision continues to provide for 

maintenance of the 1997 ozone NAAQS because the 

anthropogenic emissions of NOX and VOC in 2022 

(including the ERCs and transportation conformity 

safety margins) would be approximately 114 tpd 

and 122 tpd, respectively, which is substantially 

less than the emissions in the attainment year 

(2008) for the 1997 ozone NAAQS. 39See 40 CFR 93.124(a). 40Memorandum dated April 20, 2021, from 

Karina O’Connor, Air Planning Office, EPA Region 

IX, ‘‘Adequacy Documentation for Plan Motor 

Vehicle Emission Budgets in August 2020 Clark 

County Revision to Ozone Maintenance Plan.’’ This 

memorandum has been uploaded to the docket 

(EPA–R09–OAR–2021–0368) for this rulemaking. 

41As a general matter, VOC and NOX are also 

considered precursors for course particulate matter 

(PM10) and fine particulate matter (PM2.5). In our 

conditional approval of the 2018 Ozone 

Maintenance Plan Revision, we concluded that the 

revised budgets, even with the substantial safety 

margins, would not interfere with attainment or 

maintenance of the PM10 or PM2.5 NAAQS. 84 FR 

33035, at 33043–33044 (July 11, 2019) (proposed 

rule), finalized at 84 FR 44699 (August 27, 2019). 

Clark County is designated as attainment for the 

PM10 NAAQS and unclassifiable/attainment for the 

PM2.5 NAAQS. 40 CFR 81.329. In this document, we 

are proposing approval of budgets that have been 

revised to substantially reduce the safety margins, 

and thus, the potential for interference with 

attainment or maintenance of the PM10 or PM2.5

NAAQS is even less than it was previously. As 

such, we find that approval of the 2020 Ozone 

Maintenance Plan Revision would not interfere 

with attainment or maintenance of the PM10 or 

PM2.5 NAAQS in Clark County. 

42Letter dated December 9, 2011, from Jared 

Blumenfeld, Regional Administrator, EPA Region 

IX, to Brian Sandoval, Governor, State of Nevada. 

Plan Revision. As noted in section V.A 

of this document, Clark County DES 

developed the revised budgets using the 

latest emissions model (MOVES2014b) 

available at the time the 2020 Ozone 

Maintenance Plan Revision was being 

developed, and the most recent travel 

activity projections provided by the 

Nevada Department of Transportation 

and RTC. Therefore, we find that the 

revised budgets reflect the most recent 

planning forecasts and are based on the 

most recent emission factor data and 

approved calculation methods. 

A state may choose to allocate all or 

a portion of the safety margin 38 under 

the EPA transportation conformity rule 

so long as such margins are explicitly 

quantified in the applicable plan and 

are shown to be consistent with 

attainment or maintenance of the 

NAAQS (whichever is relevant to the 

particular plan).39 For the 2020 Ozone 

Maintenance Plan Revision, Clark 

County DES allocated a 3 tons per day 

(tpd) safety margin for NOX and VOC in 

2022 to the projected on-road emissions 

estimates for NOX and VOC. 

TABLE 4—CLARK COUNTY YEAR 2022 OZONE MOTOR VEHICLE EMISSION BUDGETS

[County-wide, average summer weekday, tpd] 

Source category 

2018 Ozone 

maintenance 

plan revision 

2020 Ozone 

maintenance 

plan revision 

NOX VOC NOX VOC 

On-Road Mobile ............................................................................................... 27.02 17.12 29.16 20.92 

Transportation Conformity Safety Margins ...................................................... 59.72 35.84 3.00 3.00 

Budgets ............................................................................................................ 86.74 52.96 32.16 23.92 

Sources: 2018 Ozone Maintenance Plan Revision, Table 3–1; 2020 Ozone Maintenance Plan Revision, Table 3–1. 

As documented in a April 20, 2021 

memorandum to the docket for this 

rulemaking, we find that the budgets in 

the 2020 Ozone Maintenance Plan 

Revision meet each adequacy 

criterion.40 In short, we reviewed the 

budgets in the 2020 Ozone Maintenance 

Plan Revision and found that they are 

consistent with the revised maintenance 

demonstration from the 2018 Ozone 

Maintenance Plan Revision; are based 

on control measures that have already 

been adopted and implemented; and 

meet all other applicable statutory and 

regulatory requirements including the 

adequacy criteria in 40 CFR 

93.1118(e)(4) and (5). Therefore, we are 

proposing to approve the 2022 budgets 

in the 2020 Ozone Maintenance Plan 

Revision. If we finalize our approval of 

the revised budgets in the 2020 Ozone 

Maintenance Plan Revision, as 

proposed, they will replace the 

corresponding budgets for the 1997 

ozone NAAQS from the 2018 Ozone 

Maintenance Plan Revision that we 

previously found adequate and 

conditionally approved for use in 

transportation conformity 

determinations. 

C. CAA Section 110(l) Evaluation 

In relevant part, CAA section 110(l) 

provides that the EPA shall not approve 

a SIP revision that would interfere with 

any applicable requirement concerning 

attainment or RFP of any of the NAAQS 

or any other applicable requirement of 

the CAA. The 2018 Ozone Maintenance 

Plan Revision established budgets that 

are larger than those that were 

previously approved from the 2011 

Ozone Maintenance Plan. Thus, 

approval of the 2018 Ozone 

Maintenance Plan Revision 

accommodated a higher level of VOC 

and NOX emissions from on-road mobile 

source emissions than would otherwise 

be allowed under the previous budgets. 

In our approval of the 2018 Ozone 

Maintenance Plan Revision, we 

evaluated the higher level of VOC and 

NOX emissions with respect to the 

potential for interference with RFP and 

attainment of the NAAQS for which 

VOC and NOX are precursors, namely, 

the 2008 and 2015 ozone NAAQS.41

In our conditional approval of the 

2018 Ozone Maintenance Plan Revision, 

we determined that if the 2018 Ozone 

Maintenance Plan Revision were revised 

to reduce the safety margin allocations 

to the budgets such that total estimated 

emissions in 2022 (with the allocations) 

would not exceed actual emissions in 

year 2017, then the updated budgets 

would not interfere with reasonable 

further progress or attainment of the 

2008 and 2015 ozone NAAQS. 

1. 2008 Ozone NAAQS 

As noted in Section II.B of this 

document, in 2012, the EPA designated 

all the hydrographic areas within the 

State of Nevada as unclassifiable/ 

attainment for the 0.075 ppm 2008 

ozone NAAQS based on ambient ozone 

concentration data for years 2009– 

2011.42 After the original designation, 

the 8-hour ozone design values within 

Clark County exceeded the 2008 ozone 


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43EPA, ‘‘Nevada, Las Vegas Nonattainment Area, 

Final Area Designations for the 2015 Ozone 

National Ambient Air Quality Standards, Technical 

Support Document (TSD).’’ 

44 In addition, if we finalize this action as 

proposed, we will be removing the conditional 

approval regulatory text found at 40 CFR 

52.1475(a). 

NAAQS for a few years but, since 2015, 

the design values have generally 

returned to attainment levels for the 

2008 ozone NAAQS. As shown in Table 

1, the design value in year 2017 was 

0.074 ppm, which is consistent with 

attainment of the 0.075 ppm 2008 ozone 

NAAQS. Thus, emissions of VOC and 

NOX in 2017 represent conditions under 

which Clark County meets the 2008 

ozone NAAQS. 

In recognition of the need to avoid 

interference with attainment of the 2008 

ozone NAAQS and progress toward 

attainment of the 2015 ozone NAAQS, 

NDEP and Clark County DES committed 

to submit a SIP revision to reduce the 

safety margin allocations to the 2022 

budgets such that total estimated 

emissions in 2022 (with the allocations) 

would not exceed actual emissions in 

year 2017, a year in which Clark County 

was attaining the 2008 ozone NAAQS. 

As shown in Table 2 of this 

document, the 2020 Ozone Maintenance 

Plan Revision estimates year 2017 

emissions in Clark County to be 

approximately 119 tpd of NOX and 488 

tpd of VOC. In 2022, as shown in Table 

3 of this document, the 2020 Ozone 

Maintenance Plan Revision estimates 

year 2022 emissions in Clark County to 

be approximately 116 tpd of NOX and 

485 tpd of VOC, including the allocated 

ERCs for stationary sources and 

transportation conformity safety 

margins for on-road mobile sources. As 

such, ozone precursor emissions in year 

2022 under the 2020 Ozone 

Maintenance Plan Revision would be 

less than those in 2017, a year in which 

Clark County was attaining the 2008 

ozone NAAQS. As such, we find that 

the 2020 Ozone Maintenance Plan 

Revision would not interfere with 

attainment of the 2008 ozone NAAQS in 

Clark County. 

2. 2015 Ozone NAAQS 

In 2018, the EPA designated the Las 

Vegas Valley (i.e., hydrographic area 

#212) as a Marginal nonattainment area 

for the 0.070 ppm 2015 ozone NAAQS 

based on ambient ozone concentration 

data for years 2015–2017.43 The 2017 

ozone design value is 0.074 ppm. To 

attain the 0.070 ppm 2015 ozone 

NAAQS by the applicable Marginal area 

attainment date, i.e., by August 3, 2021, 

VOC and NOX emissions must decrease 

relative to those in 2017. NDEP and 

Clark County DES committed to revise 

the 2018 Ozone Maintenance Plan 

Revision and the associated safety 

margins for the budgets so that, the total 

projected emissions (with the reduced 

safety margin allocations) in year 2022 

would be less than the actual emissions 

estimated for year 2017, the base year 

for implementation of the 2015 ozone 

NAAQS. 

With respect to the 2015 ozone 

NAAQS, we are finding that ozone 

precursor emissions in year 2022 under 

the 2020 Ozone Maintenance Plan 

Revision would be less than those in 

2017, the base year for implementation 

of the 2015 ozone NAAQS. As such, we 

find that the 2020 Ozone Maintenance 

Plan Revision would not interfere with 

RFP towards attainment of the 2015 

ozone NAAQS. 

VI. Proposed Action and Request for 

Public Comment 

For the reasons discussed herein, 

under CAA section 110(k)(3), the EPA is 

proposing to approve the 2020 Ozone 

Maintenance Plan Revision submitted 

by NDEP on September 30, 2020, as a 

revision for the Clark County portion of 

the Nevada SIP. We are proposing to 

approve the 2020 Ozone Maintenance 

Plan Revision because we find that the 

2011 Ozone Maintenance Plan, as 

revised by the 2018 Ozone Maintenance 

Plan Revision, and as further revised by 

the 2020 Ozone Maintenance Plan 

Revision, continues to provide for 

maintenance of the 1997 ozone NAAQS 

and will not interfere with RFP or 

attainment of the other NAAQS in Clark 

County. The EPA is also proposing to 

approve the updated budgets for 2022 

for the 1997 ozone NAAQS (shown in 

Table 4 of this document) based on our 

conclusion that the updated budgets 

meet the applicable transportation 

conformity and other CAA 

requirements. 

If the EPA takes final action to 

approve the 2020 Ozone Maintenance 

Plan Revision as proposed, the revised 

budgets will replace the corresponding 

approved budgets from the 2018 Ozone 

Maintenance Plan Revision, and RTC 

and DOT must use the revised budgets 

for future transportation conformity 

determinations for the 2015 ozone 

NAAQS until motor vehicle emissions 

budgets for that ozone NAAQS are 

found adequate or are approved.44

The EPA is soliciting public 

comments on the issues discussed in 

this document. We will accept 

comments from the public on this 

proposal for the next 30 days. We will 

consider these comments before taking 

final action. 

VII. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

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

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

submissions, the EPA’s role is to 

approve state choices, provided that 

they meet the criteria of the Clean Air 

Act. Accordingly, this proposed action 

merely proposes to approve a state plan 

as meeting federal requirements and 

does not impose additional 

requirements beyond those imposed by 

state law. For that reason, this proposed 

action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Orders 12866 (58 FR 51735, 

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

January 21, 2011); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

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

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

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

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Public Law 104–4); 

• Does not have federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

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

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

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

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide the EPA with the 

discretionary authority to address 

disproportionate human health or 

environmental effects with practical, 

appropriate, and legally permissible 

methods under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, the SIP is not approved 

to apply on any Indian reservation land 

or in any other area where the EPA or 

an Indian tribe has demonstrated that a 

tribe has jurisdiction. The Las Vegas 


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Tribe of Paiute Indians of the Las Vegas 

Indian Colony has areas of Indian 

country geographically located within 

the Clark County 1997 ozone 

maintenance area. In those areas of 

Indian country, the proposed rule does 

not have tribal implications and will not 

impose substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental 

regulations, Nitrogen dioxide, Ozone, 

Reporting and recordkeeping 

requirements, Volatile organic 

compounds. 

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

Dated: July 19, 2021. 

Deborah Jordan, 

Acting Regional Administrator, EPA Region 

IX. 

[FR Doc. 2021–16644 Filed 8–6–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 86 and 600 

[EPA–HQ–OAR–2021–0208; FRL–8824–01– 

OAR] 

RIN 2060–AV13 

Public Hearing for Revised 2023 and 

Later Model Year Light-Duty Vehicle 

Greenhouse Gas Emissions Standards 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Notification of public hearing. 

SUMMARY: The Environmental Protection 

Agency (EPA) is announcing a virtual 

public hearing to be held August 25, 

2021, on its proposal for the ‘‘Revised 

2023 and Later Model Year Light-Duty 

Vehicle Greenhouse Gas Emissions 

Standards,’’ which was signed on July 

29, 2021. An additional session will be 

held on August 26th if necessary, to 

accommodate the number of testifiers 

that sign-up to testify. EPA is proposing 

to revise the greenhouse gas (GHG) 

emissions standards for light-duty 

vehicles for 2023 and later model years 

to make the standards more stringent. 

DATES: EPA will hold a virtual public 

hearing on August 25, 2021. An 

additional session will be held on 

August 26th if necessary to 

accommodate the number of testifiers 

that sign-up to testify. Please refer to the 

SUPPLEMENTARY INFORMATION section for 

additional information on the public 

hearing. 

ADDRESSES: The virtual public hearing 

will be held on August 25, 2021. An 

additional session will be held on 

August 26th if necessary to 

accommodate the number of testifiers 

that sign-up to testify. The hearing will 

convene at 9:30 a.m. Eastern and will 

conclude when the last pre-registered 

speaker has testified but no later than 

8:00 p.m. Eastern. All hearing attendees 

(including those who do not intend to 

provide testimony) should notify the 

contact person listed under FOR FURTHER

INFORMATION CONTACT by August 18, 

2021, preferably by email to ASDRegistration@epa.gov. Additional 

information regarding the hearing 

appears below under SUPPLEMENTARY

INFORMATION. 

FOR FURTHER INFORMATION CONTACT: Tad 

Wysor, Office of Transportation and Air 

Quality, Assessment and Standards 

Division (ASD), Environmental 

Protection Agency, 2000 Traverwood 

Drive, Ann Arbor, MI 48105; telephone 

number: (734) 214–4332; email address: 

ASD-Registration@epa.gov. 

SUPPLEMENTARY INFORMATION: The 

Environmental Protection Agency (EPA) 

is proposing to revise the greenhouse 

gas (GHG) emissions standards for lightduty vehicles for 2023 and later model 

years to make the standards more 

stringent. On January 20, 2021, 

President Biden issued Executive Order 

13990 ‘‘Protecting Public Health and the 

Environment and Restoring Science To 

Tackle the Climate Crisis’’ directing 

EPA to consider whether to propose 

suspending, revising, or rescinding the 

standards previously revised under the 

‘‘The Safer Affordable Fuel-Efficient 

(SAFE) Vehicles Rule for Model Years 

2021–2026 Passenger Cars and Light 

Trucks,’’ promulgated in April 2020. 

The SAFE rule significantly weakened 

the standards established in 2012 for 

this time period. Based on our updated 

assessment, EPA is proposing under the 

Clean Air Act to revise the GHG 

standards to be more stringent than the 

SAFE rule standards in each model year 

from 2023 through 2026. EPA is also 

proposing to include several flexibilities 

to ease the auto manufacturers’ 

transition to the more stringent 

standards, including incentives for the 

production of vehicles with zero or 

near-zero emissions technology. In 

addition, EPA is proposing some 

technical amendments to clarify and 

streamline our regulations. The 

proposed revised standards would 

result in significant net benefits. The 

‘‘Revised 2023 and Later Model Year 

Light-Duty Vehicle Greenhouse Gas 

Emissions Standards’’ proposal was 

signed on July 29th and will be 

published separately in the Federal 

Register. The pre-publication version is 

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

regulations-emissions-vehicles-andengines/proposed-rule-revise-existingnational-ghg-emissions. 

Participation in Virtual Public Hearing 

Please note that EPA is deviating from 

its typical approach for public hearings. 

Because of current CDC 

recommendations, as well as state and 

local orders for social distancing to limit 

the spread of COVID–19, EPA is not 

holding in-person public meetings at 

this time. 

EPA will begin pre-registering 

speakers for the hearing upon 

publication of this document in the 

Federal Register. To register to speak at 

the virtual hearing, please contact the 

person listed in the FOR FURTHER

INFORMATION CONTACT section, preferably 

by email to ASD-Registration@epa.gov. 

The last day to pre-register to speak at 

the hearing will be August 18, 2021. 

Each commenter will have 3 minutes 

to provide oral testimony. EPA may ask 

clarifying questions during the oral 

presentations but will not respond to 

the presentations at that time. EPA 

recommends submitting the text of your 

oral comments as written comments to 

the rulemaking docket. Written 

statements and supporting information 

submitted during the comment period 

will be considered with the same weight 

as oral comments and supporting 

information presented at the public 

hearing. 

Please note that any updates made to 

any aspect of the hearing logistics, 

including any change to the date of the 

hearing or a potential additional session 

on August 26, 2021, will be posted 

online at the light-duty vehicle GHG 

rule website https://www.epa.gov/ 

regulations-emissions-vehicles-andengines/proposed-rule-revise-existingnational-ghg-emissions. While EPA 

expects the hearing to go forward as set 

forth above, please monitor our website 

or contact the person listed in the FOR

FURTHER INFORMATION CONTACT section to 

determine if there are any updates. EPA 

does not intend to publish a document 

in the Federal Register announcing 

updates. 

If you require the services of a 

translator or special accommodations 

such as audio description, please preregister for the hearing and describe 

your needs by August 18, 2021. EPA 

may not be able to arrange 

accommodations without advance 

notice. 


lotter on DSK11XQN23PROD with PROPOSALS1