Air Plan Approval; Nevada; Revisions to Clark County Ozone Maintenance Plan, 43461-43469 [2021-16644]
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[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
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
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 8hour 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
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SUMMARY:
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[Date of publication of the final rule in
the Federal Register], [Federal Register citation of the final rule].
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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
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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
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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,
1 NDEP submitted the 2020 Ozone Maintenance
Plan Revision electronically on September 30, 2020,
as an attachment to a transmittal letter dated
September 25, 2020.
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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,
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2 84
FR 44699 (August 27, 2019).
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.
3 40
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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
5 62
FR 38856 (July 18, 1997) and 40 CFR 50.10.
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.
9 Under 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
6 69
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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.
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.
12 Under 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.
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C. Transportation Conformity and the
TABLE 1—EIGHT-HOUR OZONE DESIGN VALUES FOR THE CLARK 2018 Ozone Maintenance Plan Revision
COUNTY
OZONE
MAINTENANCE
The EPA’s transportation conformity
rule at 40 CFR part 93, subpart A
AREA, 2008–2020
establishes the criteria and procedures
that metropolitan planning
Year
organizations (MPOs) and the U.S.
Department of Transportation (DOT)
2008 ......................................
0.082 must use to determine whether
2009 ......................................
0.078 transportation activities conform to the
2010 ......................................
0.076 SIP. Transportation conformity applies
2011 ......................................
0.075 to areas that are designated
2012 ......................................
0.076 nonattainment and those former
2013 ......................................
0.077 nonattainment areas that have been
2014 ......................................
0.078 redesignated to attainment and have a
2015 ......................................
0.075 CAA section 175A maintenance plan
2016 ......................................
0.075 (‘‘maintenance areas’’), but does not
2017 ......................................
0.074
apply to areas designated as attainment
2018 ......................................
0.076
17
2019 ......................................
0.073 or unclassifiable. In Clark County, the
area’s
MPO,
the
Regional
Transportation
2020 ......................................
0.074
Commission of Southern Nevada (RTC),
Source: The EPA’s 2017 and 2020 Ozone and DOT are the relevant transportation
Design
Values
Reports
at
https://
agencies that must determine the
www.epa.gov/air-trends/air-quality-design-values#report. Note that design values reported conformity of transportation plans and
for a given year reflect data from that year and transportation improvement plans
the two previous years, e.g., the design value (TIPs) within Clark County.
for 2008 reflects data from 2006–2008.
Under our transportation conformity
rule, the latest approved or adequate
B. 2008 and 2015 Ozone NAAQS
emissions budgets for a previous ozone
In 2008, the EPA lowered the ozone
NAAQS (i.e., the 2008 or the 1997 ozone
NAAQS to a level of 0.075 ppm, 8-hour
NAAQS) must be used in conformity
average (herein, the ‘‘2008 ozone
determinations for the 2015 ozone
NAAQS’’),13 and in 2012, the EPA
NAAQS until emission budgets are
designated all of the hydrographic areas established and found adequate or are
within the State of Nevada as
approved for the 2015 ozone NAAQS.
‘‘Unclassifiable/Attainment’’ for the
Because the latest approved or adequate
2008 ozone NAAQS.14 Because all the
emissions budgets for a previous ozone
hydrographic areas located entirely, or
NAAQS for Clark County are the
partially, within Clark County were
approved budgets for the 1997 8-hour
designated as unclassifiable/attainment
ozone NAAQS, the RTC and DOT must
for the 2008 ozone NAAQS, no
use these budgets for conformity
reasonable further progress (RFP) or
determinations for the 2015 ozone
attainment SIP revision was required for NAAQS 18 until they are replaced by
any portion of the county.
updated budgets for the 2015 ozone
In 2015, the EPA further lowered the
NAAQS.
ozone NAAQS to 0.070 ppm, 8-hour
In 2018, NDEP submitted the 2018
average (herein the ‘‘2015 ozone
Ozone Maintenance Plan Revision as a
NAAQS’’).15 In 2018, the EPA
revision to the Clark County portion of
designated the Las Vegas Valley portion the Nevada SIP. The 2018 Ozone
of Clark County as a ‘‘Marginal’’
Maintenance Plan Revision includes
nonattainment area for the 2015 ozone
revisions to the attainment inventory,
NAAQS, effective August 3, 2018.16 The the maintenance demonstration, and
nonattainment area designation for Las
budgets in the 2011 Ozone Maintenance
Vegas Valley for the 2015 ozone NAAQS Plan to reflect updated emissions
triggered the requirement for certain SIP models, vehicle mix and speed data,
revisions under CAA section 182(a) and and transportation activity projections.
the EPA’s related SIP Requirements
The 2018 Ozone Maintenance Plan
Rule promulgated at 40 CFR part 51,
Revision revised the budgets for NOX
subpart CC.
and VOC for years 2008, 2015, and
2022. The revised budgets were derived
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Design
value
(ppm)
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).
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17 CAA
section 176(c)(5).
18 The 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.
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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
19 84
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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.
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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
20 Clark County Board of County Commissioners
Meeting, Meeting Summary, October 16, 2018, 14
and 15.
21 Letter 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).
22 Appendix 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
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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
revision was published on June 25, 2020, on the
County’s webpage. No comments were submitted.
23 The 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.
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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.
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.
25 The 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.
26 The 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.
27 For 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.
28 See Table 2–1 in the 2020 Ozone Maintenance
Plan Revision.
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TABLE 2—2017 CLARK COUNTY OZONE PRECURSOR EMISSION INVENTORY
[County-wide, average summer weekday, tons per day]
NOX emissions
2020 Ozone
maintenance
plan revision
Source category
VOC emissions
2018 Ozone
maintenance
plan revision
2020 Ozone
maintenance
plan revision
2018 Ozone
maintenance
plan revision
Point source .....................................................................................................
Nonpoint source ...............................................................................................
Commercial aviation ........................................................................................
Federal aviation ...............................................................................................
On-road mobile ................................................................................................
Nonroad mobile ...............................................................................................
Biogenic ...........................................................................................................
12.40
7.651
11.47
0.50
46.96
37.45
2.43
11.79
5.68
13.38
1.77
53.65
24.78
5.00
2.95
62.56
1.73
0.24
29.47
28.25
362.61
2.51
59.94
2.75
1.04
28.49
30.36
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]
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NOX emissions
Source category
2020 Ozone
maintenance
plan revision
Point source .....................................................................................................
29 2020 Ozone Maintenance Plan Revision,
Appendix A, 4–12.
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2018 Ozone
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plan revision
12.09
30 https://www.epa.gov/air-emissions-modeling/
biogenic-emission-inventory-system-beis.
VOC emissions
12.26
31 2011
32 2020
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3.12
2018 Ozone
maintenance
plan revision
2.72
Ozone Maintenance Plan, 6–4.
Ozone Maintenance Plan Revision, 14.
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TABLE 3—2022 CLARK COUNTY OZONE PRECURSOR EMISSION INVENTORY—Continued
[County-wide, average summer weekday, tons per day]
NOX emissions
2020 Ozone
maintenance
plan revision
Source category
VOC emissions
2018 Ozone
maintenance
plan revision
2020 Ozone
maintenance
plan revision
2018 Ozone
maintenance
plan revision
Nonpoint source ...............................................................................................
Commercial aviation ........................................................................................
Federal aviation ...............................................................................................
On-road mobile ................................................................................................
Nonroad mobile ...............................................................................................
Biogenic ...........................................................................................................
Emission reduction credits ...............................................................................
Transportation conformity safety margins .......................................................
7.57
13.08
1.97
29.16
24.93
2.43
22.23
3.00
5.04
17.42
2.26
27.02
17.50
5.00
22.23
59.72
62.58
1.73
0.82
20.92
26.71
362.61
0.43
3.00
59.49
2.95
0.95
17.12
28.52
132.00
0.43
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–
lotter on DSK11XQN23PROD with PROPOSALS1
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.
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.
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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
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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
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: https://www.epa.gov/otaq/stateresources/
transconf/index.htm.
35 40 CFR 93.118(f)(2).
36 Under the transportation conformity
regulations, the EPA may review the adequacy of
submitted motor vehicle emission budgets
simultaneously with the EPA’s approval or
disapproval of the submitted implementation plan.
40 CFR 93.118(f)(2).
37 The 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.
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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
43467
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]
2018 Ozone
maintenance
plan revision
Source category
NOX
On-Road Mobile ...............................................................................................
Transportation Conformity Safety Margins ......................................................
Budgets ............................................................................................................
2020 Ozone
maintenance
plan revision
VOC
27.02
59.72
86.74
NOX
17.12
35.84
52.96
29.16
3.00
32.16
VOC
20.92
3.00
23.92
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Sources: 2018 Ozone Maintenance Plan Revision, Table 3–1; 2020 Ozone Maintenance Plan Revision, Table 3–1.
conditionally approved for use in
transportation conformity
determinations.
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.
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
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
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
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.
39 See 40 CFR 93.124(a).
40 Memorandum 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.
41 As a general matter, VOC and NO are also
X
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.
42 Letter dated December 9, 2011, from Jared
Blumenfeld, Regional Administrator, EPA Region
IX, to Brian Sandoval, Governor, State of Nevada.
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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.
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
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.
43 EPA, ‘‘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).
2. 2015 Ozone NAAQS
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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.
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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
Environmental Protection
Agency (EPA).
ACTION: Notification of public hearing.
AGENCY:
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
lotter on DSK11XQN23PROD with PROPOSALS1
SUMMARY:
VerDate Sep<11>2014
16:39 Aug 06, 2021
Jkt 253001
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
PO 00000
Frm 00041
Fmt 4702
Sfmt 4702
43469
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.
E:\FR\FM\09AUP1.SGM
09AUP1
]]>Agencies
[Federal Register Volume 86, Number 150 (Monday, August 9, 2021)]
[Proposed Rules]
[Pages 43461-43469]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-16644]
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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.
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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 [email protected].
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,
[[Page 43462]]
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
previously-approved 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\
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\1\ NDEP submitted the 2020 Ozone Maintenance Plan Revision
electronically on September 30, 2020, as an attachment to a
transmittal letter dated September 25, 2020.
\2\ 84 FR 44699 (August 27, 2019).
\3\ 40 CFR 93.118(f)(2)(v).
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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, quality-assured, and certified
ambient air monitoring data that showed the area monitored attainment
of the 1997 ozone NAAQS for the 2007-2009 monitoring period.\7\
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\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).
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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\
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\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.
\9\ Under 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).
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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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\11\ 2011 Ozone Maintenance Plan, 6-11.
\12\ Under 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 fourth-highest 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.
[[Page 43463]]
Table 1--Eight-Hour Ozone Design Values for the Clark County Ozone
Maintenance Area, 2008-2020
------------------------------------------------------------------------
Design value
Year (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.
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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).
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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.
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\15\ 80 FR 65292 (October 26, 2015) and 40 CFR 50.19.
\16\ 83 FR 25776 (June 4, 2018).
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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.
---------------------------------------------------------------------------
\17\ CAA section 176(c)(5).
---------------------------------------------------------------------------
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.
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\18\ The 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.
---------------------------------------------------------------------------
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 on-road 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\
---------------------------------------------------------------------------
\19\ 84 FR 44699 (August 27, 2019).
---------------------------------------------------------------------------
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
[[Page 43464]]
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).
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\20\ Clark County Board of County Commissioners Meeting, Meeting
Summary, October 16, 2018, 14 and 15.
\21\ Letter 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).
---------------------------------------------------------------------------
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.
---------------------------------------------------------------------------
\22\ Appendix 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.
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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.
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\23\ The 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.
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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\
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\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.
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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.
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\25\ The 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.
\26\ The 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.
\27\ For 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.
\28\ See Table 2-1 in the 2020 Ozone Maintenance Plan Revision.
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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 on-road mobile source
category and the nonroad source category as well as a change in the
methodology for biogenic emissions.
[[Page 43465]]
Table 2--2017 Clark County Ozone Precursor Emission Inventory
[County-wide, average summer weekday, tons per day]
----------------------------------------------------------------------------------------------------------------
NOX emissions VOC emissions
---------------------------------------------------------------
Source category 2020 Ozone 2018 Ozone 2020 Ozone 2018 Ozone
maintenance maintenance maintenance maintenance
plan revision plan revision plan revision 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.
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\29\ 2020 Ozone Maintenance Plan Revision, Appendix A, 4-12.
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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.
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\30\ https://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.
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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]
----------------------------------------------------------------------------------------------------------------
NOX emissions VOC emissions
---------------------------------------------------------------
Source category 2020 Ozone 2018 Ozone 2020 Ozone 2018 Ozone
maintenance maintenance maintenance maintenance
plan revision plan revision plan revision plan revision
----------------------------------------------------------------------------------------------------------------
Point source.................................... 12.09 12.26 3.12 2.72
[[Page 43466]]
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\
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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.
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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\
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\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: https://www.epa.gov/otaq/stateresources/transconf/index.htm.
\35\ 40 CFR 93.118(f)(2).
\36\ Under the transportation conformity regulations, the EPA
may review the adequacy of submitted motor vehicle emission budgets
simultaneously with the EPA's approval or disapproval of the
submitted implementation plan. 40 CFR 93.118(f)(2).
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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
[[Page 43467]]
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.
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\37\ The 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.
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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.
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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.
\39\ See 40 CFR 93.124(a).
Table 4--Clark County Year 2022 Ozone Motor Vehicle Emission Budgets
[County-wide, average summer weekday, tpd]
----------------------------------------------------------------------------------------------------------------
2018 Ozone maintenance plan 2020 Ozone maintenance plan
revision revision
Source category ---------------------------------------------------------------
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.
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\40\ Memorandum 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.
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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\
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\41\ As 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.
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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
[[Page 43468]]
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.
---------------------------------------------------------------------------
\42\ Letter dated December 9, 2011, from Jared Blumenfeld,
Regional Administrator, EPA Region IX, to Brian Sandoval, Governor,
State of Nevada.
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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.
---------------------------------------------------------------------------
\43\ EPA, ``Nevada, Las Vegas Nonattainment Area, Final Area
Designations for the 2015 Ozone National Ambient Air Quality
Standards, Technical Support Document (TSD).''
---------------------------------------------------------------------------
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\
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\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).
---------------------------------------------------------------------------
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
[[Page 43469]]
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
