Proposed Rule2026-20102
Approval of Implementation Plans for Air Quality Planning Purposes; State of Nevada; Truckee Meadows Second 10-Year Maintenance Plan for the 1987 PM-10 Standard
Primary source
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Published
October 1, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The U.S. Environmental Protection Agency (EPA) is proposing to approve the "Second 10-Year Maintenance Plan for the Truckee Meadows 24-Hour PM<INF>10</INF> Attainment Area" ("Truckee Meadows Second PM<INF>10</INF> Maintenance Plan" or "Plan") as a revision to the Washoe County portion of the State implementation plan (SIP) for the State of Nevada. The Truckee Meadows Second PM<INF>10</INF> Maintenance Plan includes, among other elements, a base year emissions inventory, a maintenance demonstration, contingency provisions, and motor vehicle emissions budgets for use in transportation conformity determinations. With this proposed rulemaking, the EPA is initiating the adequacy process for the 2025, 2030, and 2040 motor vehicle emissions budgets. The EPA is proposing these actions because the SIP revision meets the applicable statutory and regulatory requirements for such plans and motor vehicle emissions budgets. We are taking comments on this proposal and plan to follow with a final action.
Full Text
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<title>Federal Register, Volume 91 Issue 189 (Thursday, October 1, 2026)</title>
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[Federal Register Volume 91, Number 189 (Thursday, October 1, 2026)]
[Proposed Rules]
[Pages 62371-62380]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-20102]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2025-1978; FRL-13551-01-R9]
Approval of Implementation Plans for Air Quality Planning
Purposes; State of Nevada; Truckee Meadows Second 10-Year Maintenance
Plan for the 1987 PM-10 Standard
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing to
approve the ``Second 10-Year Maintenance Plan for the Truckee Meadows
24-Hour PM<INF>10</INF> Attainment Area'' (``Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan'' or ``Plan'') as a revision to the
Washoe County portion of the State implementation plan (SIP) for the
State of Nevada. The Truckee Meadows Second PM<INF>10</INF> Maintenance
Plan includes, among other elements, a base year emissions inventory, a
maintenance demonstration, contingency provisions, and motor vehicle
emissions budgets for use in transportation conformity determinations.
With this proposed rulemaking, the EPA is initiating the adequacy
process for the 2025, 2030, and 2040 motor vehicle emissions budgets.
The EPA is proposing these actions because the SIP revision meets the
applicable statutory and regulatory requirements for such plans and
motor vehicle emissions budgets. We are taking comments on this
proposal and plan to follow with a final action.
DATES: Comments must be received on or before November 2, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2025-1978, at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. For comments submitted
at <a href="http://Regulations.gov">Regulations.gov</a>, follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
<a href="http://Regulations.gov">Regulations.gov</a>. 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 <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>. If you need assistance in a
language other than English or if you are a person with a disability
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: Ginger Vagenas, EPA Region IX, 75
Hawthorne St., San Francisco, CA 94105; telephone number: (415) 972-
3964; email address: <a href="/cdn-cgi/l/email-protection#95e3f4f2f0fbf4e6bbf2fcfbf2f0e7d5f0e5f4bbf2fae3"><span class="__cf_email__" data-cfemail="40362127252e21336e27292e272532002530216e272f36">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA. We use multiple abbreviations in this
preamble. While the following list may not be exhaustive, for ease of
reading and for reference purposes, the EPA defines the following
abbreviations here:
Act: Clean Air Act
AERR: Air Emissions Reporting Requirements rule
AQMD: Air Quality Management Division
AQS: EPA Air Quality System database
CAA: Clean Air Act
Calcagni Memo: September 4, 1992 EPA memorandum from John Calcagni,
titled ``Procedures for Processing Requests to Redesignate Areas to
Attainment''
CBI: Confidential Business Information
CMTC: Contingency Measure Trigger Calculation
DBOH: District Board of Health
EPA: U.S. Environmental Protection Agency
FHWA: Federal Highway Administration
FTA: Federal Transit Administration
lbs/day: Pounds per Day
[mu]g/m\3\: micrograms per cubic meter
NAAQS: National Ambient Air Quality Standard
NDEP: Nevada Division of Environmental Protection
NEI: National Emissions Inventory
NNPH: Northern Nevada Public Health
NO<INF>X</INF>: Nitrogen Oxides
Plan: Second 10-Year Maintenance Plan for the Truckee Meadows 24-
Hour PM<INF>10</INF> Attainment Area or Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan
PM<INF>10</INF>: Inhalable particles with diameters that are 10
micrometers or less.
SIP: State Implementation Plan
SLAMS: State and Local Air Monitoring Stations
SO<INF>X</INF>: Sulfur Oxides
VOC: Volatile Organic Compound
Table of Contents
I. Background
A. What action is the EPA proposing to take?
B. What is the legal authority and what are the requirements?
C. The PM<INF>10</INF> National Ambient Air Quality Standards
D. The Truckee Meadows PM<INF>10</INF> Planning Area
E. PM<INF>10</INF> Planning in the Truckee Meadows Area
II. Air Quality in the Truckee Meadows Area
III. Procedural Requirements for Adoption and Submittal of State
Implementation Plan Revisions
IV. Evaluation of the Truckee Meadows Second PM<INF>10</INF>
Maintenance Plan
A. Emissions Inventory
B. Maintenance Demonstration
C. PM<INF>10</INF> Air Quality Monitoring Network
D. Verification of Continued Attainment
E. Contingency Provisions
F. Motor Vehicle Emissions Budgets for Transportation Conformity
V. Proposed Action and Request for Public Comment
VI. Statutory and Executive Order Reviews
I. Background
A. What action is the EPA proposing to take?
The EPA is proposing to approve the Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan as a revision to the Washoe County
portion of the SIP for the State of Nevada. We are also initiating the
adequacy process for the 2025, 2030, and 2040 motor vehicle emissions
budgets.
B. What is the legal authority and what are the requirements?
Clean Air Act (CAA or ``Act'') section 175A(b) requires States to
submit an additional SIP revision (a second 10-year maintenance plan)
to maintain the national ambient air quality standards (NAAQS or
``standards'') for an additional 10 years after the expiration of the
10-year period covered by the initial maintenance plan approved in
[[Page 62372]]
connection with the redesignation of the area from nonattainment to
attainment.
CAA section 176(c) 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 expeditious attainment of the standards. The EPA's
transportation conformity rule, which implements CAA section 176(c), is
codified at 40 CFR part 93, subpart A.
C. The PM10 National Ambient Air Quality Standards
CAA section 109 grants the EPA the authority to set NAAQS for
certain ambient air pollutants to protect public health and welfare.\1\
Particulate matter (PM) refers to the mixture of solid particles and
liquid droplets found in the air. PM is among the ambient air
pollutants for which the EPA has established health-based standards.
PM<INF>10</INF> is defined as inhalable particles with diameters that
are 10 micrometers or less. PM<INF>10</INF> can cause adverse health
effects by penetrating deep into the lungs and blood stream, leading to
lung damage, increased respiratory disease, and premature death.
Children, the elderly, and people with asthma and heart conditions are
the most vulnerable.
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\1\ CAA section 109(b). For a given air pollutant, ``primary''
standards are those determined by the EPA as requisite to protect
the public health. ``Secondary'' standards are those determined by
the EPA as requisite to protect the public welfare from any known or
anticipated adverse effects associated with the presence of such air
pollutant in the ambient air.
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On July 1, 1987, the EPA established primary and secondary NAAQS
for PM<INF>10</INF>.\2\ At that time, the EPA established two
PM<INF>10</INF> standards: an annual standard and a 24-hour
standard.\3\ Effective December 18, 2006, the EPA revoked the annual
PM<INF>10</INF> standard but retained the 24-hour PM<INF>10</INF>
standard.\4\ An area attains the 24-hour standard of 150 micrograms per
cubic meter ([micro]g/m\3\) when the expected number of days per
calendar year with a 24-hour concentration above the standard (referred
to as an ``exceedance''),\5\ averaged over three years, is equal to or
less than one. The expected number of exceedances averaged over a
three-year period at any regulatory monitor is known as the
PM<INF>10</INF> design value. The PM<INF>10</INF> design value for the
area is the highest design value within the nonattainment area.\6\
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\2\ 52 FR 24634 (July 1, 1987).
\3\ The primary and secondary standards were set at the same
level for both the 24-hour and the annual PM<INF>10</INF> standards.
\4\ 71 FR 61144 (October 17, 2006).
\5\ An exceedance is defined as a daily value that is above the
level of the 24-hour standard (i.e., 150 [micro]g/m\3\) after
rounding to the nearest 10 [micro]g/m\3\ (i.e., values ending in
five or greater are to be rounded up). Thus, a recorded value of 154
[micro]g/m\3\ would not be an exceedance because it would be rounded
to 150 [micro]g/m\3\. A recorded value of 155 [micro]g/m\3\ would be
an exceedance because it would be rounded to 160 [micro]g/m\3\. 40
CFR part 50, appendix K, section 1.0.
\6\ 40 CFR 50.6 and 40 CFR part 50, appendix K. The comparison
with the allowable expected exceedance rate of one per year averaged
over three years is made in terms of a number rounded to the nearest
tenth (fractional values equal to or greater than 0.05 are to be
rounded up; e.g., an exceedance rate of 1.05 would be rounded to
1.1, which is the minimum design value for nonattainment). 40 CFR
part 50, appendix K, section 2.1(b).
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Generally, the EPA determines whether an area's air quality is
meeting the PM<INF>10</INF> NAAQS based on the most recent complete,\7\
quality-assured, and certified data measured at established State and
local air monitoring stations (SLAMS) in the nonattainment area and
entered into the EPA Air Quality System (AQS) database. Data from air
monitoring sites operated by State, local, or Tribal agencies in
compliance with the EPA's monitoring requirements must be submitted to
AQS. These monitoring agencies annually certify that these data are
accurate to the best of their knowledge. Accordingly, the EPA relies
primarily on data in AQS when determining the attainment status of an
area.\8\ All valid data are reviewed to determine the area's air
quality status in accordance with 40 CFR part 50, appendix K.
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\7\ For PM<INF>10</INF>, a complete year of air quality data
includes all four calendar quarters with each quarter having valid
data on a minimum of 75 percent of the scheduled PM<INF>10</INF>
sampling days. 40 CFR part 50, appendix K, section 2.3(a).
\8\ 40 CFR 50.6; 40 CFR part 50, appendix J; 40 CFR part 53; and
40 CFR part 58, appendices A, C, D, and E.
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D. The Truckee Meadows PM10 Planning Area
Through its enactment of the CAA Amendments of 1990, Congress
designated certain areas of the country, including the Reno planning
area, commonly referred to as ``Truckee Meadows,'' as nonattainment
areas for the PM<INF>10</INF> NAAQS. Truckee Meadows lies in the far
southern part of Washoe County, Nevada.\9\ Located at an average
elevation of 4,500 feet above sea level, Truckee Meadows encompasses a
land area of approximately 200 square miles and is surrounded by
mountain ranges, which can lead to persistent wintertime temperature
inversions where a layer of cold air is trapped in the valley. Warmer
air above the inversion acts as a lid, containing and concentrating air
pollutants at ground level. Emissions from anthropogenic activities
such as automobile use and residential wood combustion are also
concentrated here. The two major cities in Truckee Meadows are Reno and
Sparks.
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\9\ Washoe County is located in the northwestern portion of
Nevada and is bordered by the State of California to the west and
the State of Oregon to the north. Within the State of Nevada, the
counties of Humboldt, Pershing, Storey, Churchill, Lyon, and the
city of Carson City bound Washoe County to the east and south.
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E. PM10 Planning in the Truckee Meadows Area
In 1991, the Reno planning area (i.e., Truckee Meadows) was
designated as a nonattainment area for PM<INF>10</INF> by operation of
law.\10\ Truckee Meadows was initially classified as a ``Moderate''
PM<INF>10</INF> nonattainment area with an applicable attainment date
of December 31, 1994.\11\ Truckee Meadows was later reclassified by
operation of law to ``Serious'' upon the EPA's determination that,
based on ambient PM<INF>10</INF> data for the 1992 through 1994 period,
the area had failed to attain the standard by the Moderate area
attainment date.\12\ The State was required under CAA section 188(c) to
submit revisions to its SIP to, among other things, demonstrate
attainment of the PM<INF>10</INF> standard as expeditiously as
practicable, but no later than December 31, 2001. Despite further
improvements, in a 2011 rulemaking, the EPA found that Truckee Meadows
failed to attain by the December 31, 2001 attainment date, based on
ambient PM<INF>10</INF> data for the 1999 through 2001 period.\13\
Under such circumstances, the State would usually be required to submit
a new attainment plan under CAA section 189(d). However, in the same
2011 rulemaking, the EPA determined that the area was currently
attaining the PM<INF>10</INF> NAAQS based on complete, quality-assured,
and certified ambient air monitoring data that showed the area
monitored attainment of the 1987 p.m.<INF>10</INF> NAAQS for the 2007
through 2009 monitoring period. Consequently, the requirement to submit
a new SIP was suspended.
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\10\ 56 FR 11101 (March 15, 1991).
\11\ Id.
\12\ 66 FR 1268 (January 8, 2001).
\13\ 76 FR 21807 (April 19, 2011).
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When a nonattainment area attains the NAAQS, the State may request
redesignation to attainment, in conjunction with submission of a
maintenance plan showing how it will continue to attain the NAAQS. CAA
section 175A provides the general framework for a maintenance plan. The
maintenance plan must provide for continued attainment of the NAAQS for
at least 10 years after redesignation, including any additional control
measures necessary to ensure such maintenance. In addition, maintenance
plans must contain contingency provisions necessary to ensure the
[[Page 62373]]
prompt correction of a violation of the NAAQS that occurs after
redesignation.\14\ The contingency provisions must include, at a
minimum, a requirement that the State will implement all control
measures contained in the nonattainment SIP prior to redesignation.
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\14\ CAA section 175A(d).
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After verifying the area continued to attain the NAAQS and that
Nevada had submitted an approvable plan to continue maintenance of the
NAAQS through 2026, the EPA redesignated the Truckee Meadows area from
nonattainment to attainment and approved the first maintenance plan for
the Truckee Meadows area for the PM<INF>10</INF> NAAQS, effective
January 7, 2016.\15\
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\15\ 80 FR 76232 (December 8, 2015).
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CAA section 175A(b) requires States to submit an additional SIP
revision (a second 10-year maintenance plan) to maintain the NAAQS for
an additional 10 years after the expiration of the 10-year period
covered by the initial maintenance plan approved in connection with the
redesignation of the area from nonattainment to attainment. The
revision is to be submitted eight years after the original
redesignation request and maintenance plan have been approved. The
deadline to submit the second PM<INF>10</INF> maintenance plan for
Truckee Meadows was January 7, 2024.
II. Air Quality in the Truckee Meadows Area
A recent design value showing a maintenance area is continuing to
attain the PM<INF>10</INF> NAAQS (i.e., the recorded number of days
with levels above 150 [micro]g/m\3\, averaged over a 3-year period, is
less than or equal to one) is the foundation of a second 10-year
maintenance plan. As described in more detail in section IV.A of this
document, a base year emissions inventory from the design value period
that represents attainment conditions is used as the basis for
projecting emissions inventories into the future and to demonstrate
that future emissions will not lead to an exceedance of the standards.
Northern Nevada Public Health \16\ (NNPH), which administers air
quality programs through its Air Quality Management Division (AQMD),
used the data from calendar years 2017 through 2019 to calculate a 2019
design value to demonstrate the area had continued to attain the
PM<INF>10</INF> standard and selected the 2017 emissions inventory as
its base year inventory.
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\16\ Prior to August of 2023, Northern Nevada Public Health was
known as Washoe County Health District. For simplicity, we use the
current name when referring to actions that occurred both before and
after the agency adopted the new name.
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Table 1 of this document shows the design values for the Truckee
Meadows PM<INF>10</INF> maintenance area at the monitoring sites active
in the maintenance area from 2016 through 2025, accounting for all
recorded exceedances during that time. Table 2 of this document shows
the number of exceedances recorded at active monitors for the years
2016 through 2025.\17\
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\17\ The EPA approved the discontinuation of the Galletti
monitor in 2015 and the Plum-Kit and South Reno monitors in 2017.
Correspondence documenting NNPH requests and EPA approval of
modifications to the monitoring network is included in Appendix K of
the Truckee Meadows Second PM<INF>10</INF> Maintenance Plan.
Table 1--Design Values for the First 10-Year Maintenance Period \a\
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Monitor (AQS ID) 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
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Galletti (32-0031-0022)....................................... * 0.3 n/a n/a n/a n/a n/a n/a n/a n/a n/a
Toll (32-031-0025)............................................ 0.3 0.3 0.0 0.0 1.0 4.0 5.3 4.3 1.3 0.0
Sparks (32-031-1005).......................................... 0.0 0.0 0.0 0.0 1.0 2.7 3.0 2.0 0.3 0.0
Reno4 (32-031-0031) \b\....................................... 0.0 0.0 0.0 0.0 0.3 2.7 3.7 3.3 1.0 0.0
Plumb-Kit (32-031-0030)....................................... 0.0 0.0 * 0.0 * 0.0 n/a n/a n/a n/a n/a n/a
South Reno (32-031-0020)...................................... 0.0 0.0 * 0.0 * 0.0 n/a n/a n/a n/a n/a n/a
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\a\ Design values marked with an asterisk are invalid. The 2016 design value for Galletti and the 2018 and 2019 design values for Plumb-Kit and South
Reno are invalid due to incomplete data following the shutdown of the monitoring sites.
\b\ The Reno3 monitoring site (AQS ID: 32-031-0016) was relocated to Reno4 in 2020 and the data have been combined into a single data record.
Source: Truckee Meadows Second PM10 Maintenance Plan, Table 9, and EPA AQS PM10 Design Value Report, AMP 480, for 2016 through 2025 (accessed July 20,
2026).
Table 2--Estimated Exceedances During the First 10-Year Maintenance Period
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Monitor (AQS ID) 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
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Galletti (32-031-0022)...................... 1 0 0 n/a n/a n/a n/a n/a n/a n/a n/a n/a
Toll (32-031-0025).......................... 0 1 0 0 0 0 3 9 4 0 0 0
Sparks (32-031-1005)........................ 0 0 0 0 0 0 3 5 1 0 0 0
Reno4 (32-031-0031)......................... 0 0 0 0 0 0 1 7 3 0 0 0
Plumb-Kit (32-031-0030)..................... 0 0 0 0 n/a n/a n/a n/a n/a n/a n/a n/a
South Reno (32-031-0020).................... 0 0 0 0 n/a n/a n/a n/a n/a n/a n/a n/a
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Source: Truckee Meadows Second PM10 Maintenance Plan, Table 10, and EPA AQS PM10 Design Value Report, AMP 480, for 2016 through 2025 (accessed July 20,
2026).
Between 2016 and 2025, exceedances occurred during three years--
2020, 2021, and 2022--which led to violations of the PM<INF>10</INF>
NAAQS. Because the PM<INF>10</INF> design value is based on a 3-year
average, exceedances from the prior two years are factored into the
design value for the current year, resulting in design values that
violated the PM<INF>10</INF> NAAQS in 2023 and 2024, even though no
exceedances occurred in those years.
CAA section 175A(d) requires that maintenance plans contain
contingency provisions as deemed necessary by the EPA that assure the
air agency will promptly correct violations of the standard that occur
after an area is redesignated.\18\ During the first 10-year maintenance
period, for violations that occur outside the design value period on
which the second maintenance plan is based, air agencies typically
evaluate exceedances to determine the cause and to determine any
necessary steps, including rulemaking, they should take to correct the
violation. If violations are caused by events that are not reasonably
controllable or preventable, e.g., wildfires, air agencies are not
required to adopt maintenance plan contingency measures.
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\18\ The requirements for contingency provisions are discussed
in greater detail in section IV.E of this document.
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NNPH analyzed the exceedances that contributed to violations of the
PM<INF>10</INF> standard during the first maintenance period to
ascertain the cause and what
[[Page 62374]]
(if any) actions they should take to address the causes, and concluded
that wildfire events led to the exceedances.\19\ The EPA has reviewed
the information included in the Truckee Meadows Second PM<INF>10</INF>
Maintenance Plan regarding the exceedances that occurred during the
first maintenance period, and we agree that this information does not
call into question the EPA's proposed approval of this Plan. We also
note that NNPH's analysis and the EPA's evaluation are consistent with
the contingency provisions of the maintenance plan that we are
proposing to approve in this rulemaking to evaluate data that may have
been influenced by certain events in determining whether contingency
provisions should be triggered.
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\19\ Appendices G through J of the Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan include analyses of the exceedances
on July 26, 2021, August 6 through August 7, 2021, August 17, 2021,
August 20 through August 26, 2021, September 11, 2021, and September
14 through September 16, 2022.
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III. Procedural Requirements for Adoption and Submittal of State
Implementation Plan Revisions
The Nevada Division of Environmental Protection (NDEP) is the State
agency with overall responsibility for the Nevada SIP and is the
designated agency for submitting SIPs and SIP revisions to the EPA for
approval. NNPH is empowered under State law to develop air quality
plans within Washoe County. After it adopts an air quality plan for
Washoe County, NNPH submits the plan to NDEP for adoption as part of
the Nevada SIP and then for submittal to the EPA for approval.
On September 12, 2024, NDEP submitted a second PM<INF>10</INF> 10-
year maintenance plan for the Truckee Meadows 24-hour PM<INF>10</INF>
attainment area to meet the requirement for the subsequent maintenance
plan under CAA section 175A(b).\20\ On January 22, 2026, NNPH adopted
revisions to that plan and on March 12, 2026, NDEP submitted the
revised version of the second PM<INF>10</INF> 10-year maintenance plan,
which superseded the initial September 2024 submittal.\21\ In this
action, we are proposing to approve NDEP's March 12, 2026 submittal of
its second PM<INF>10</INF> 10-year maintenance plan (referred to herein
as the ``Truckee Meadows Second PM<INF>10</INF> Maintenance Plan'' or
``Plan'') as a revision to the Nevada SIP. The Plan is intended to
provide for continued maintenance of the 1987 p.m.<INF>10</INF> NAAQS
for the 10-year period following the end of the first 10-year period,
i.e., from 2026 through 2035.
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\20\ Letter dated September 13, 2024, from Jennifer Carr,
Administrator, NDEP, to Matthew Lakin, Director, Air and Radiation
Division, EPA Region 9. Note that the Plan and transmittal letter
were submitted electronically to EPA on September 12, 2024.
\21\ The Plan was revised to remove the commitment to undertake
a triennial home heating survey, which was used to verify continued
attainment of the NAAQS and to establish the maintenance emissions
limit for the first maintenance plan. (``Redesignation Request and
Maintenance Plan for the Truckee Meadows 24-Hour PM<INF>10</INF>
Nonattainment Area,'' August 28, 2014, pages 26 and 31.) NNPH
determined that the survey was no longer necessary due to
improvements in the EPA's methodology to account for residential
wood combustion emissions. See the media release announcing the
public comment period, Attachment 1 to the transmittal letter dated
March 12, 2026, from Jennifer Carr, Administrator, NDEP, to Michele
Angelich, Air and Radiation Division Acting Director, EPA Region 9.
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CAA sections 110(a)(1) and (2) and CAA section 110(1) require
States to provide reasonable notice and public hearing prior to
adoption of SIP revisions. On November 26, 2025, NNPH posted a media
release to the NNPH website announcing the proposed revision to the
previously submitted second PM<INF>10</INF> Maintenance Plan, informing
the public of a public comment period ending December 26, 2025, and the
option to request a public hearing that would take place on January 22,
2026. NNPH also notified via email all subscribers to its mailing list
of the public comment period.\22\ No comments were submitted and a
public hearing was not requested.\23\ Consequently, the adoption of the
plan was listed as a consent item on the NNPH District Board of Health
(DBOH) agenda for its January 22, 2026 meeting.\24\ At that meeting, no
comments were offered by the public, and the NNPH DBOH adopted the
Truckee Meadows Second PM<INF>10</INF> Maintenance Plan.\25\ Following
adoption, NNPH forwarded the plan to NDEP, the Governor of Nevada's
designee for SIP matters. NDEP then submitted the plan as a revision to
the Nevada SIP to the EPA for approval on March 12, 2026.
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\22\ A copy of the announcement NNPH transmitted to the
subscribers of its mailing list is included in the docket for this
proposed rulemaking.
\23\ Plan, page 27.
\24\ Attachment 2 of the March 12, 2026 submittal (``DBOH agenda
for the January 22, 2026 adoption'').
\25\ Attachment 6 of the March 12, 2026 submittal (``Certificate
of Adoption''). Minutes from the January 22, 2026 DBOH meeting are
included as Attachment 5 of the submittal (``Approved minutes from
the January 22, 2026 adoption'').
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Based on the documentation included in the Plan, we find that the
Truckee Meadows Second PM<INF>10</INF> Maintenance Plan submittal
satisfies the procedural requirements of CAA section 110(l).
IV. Evaluation of the Truckee Meadows Second PM10 Maintenance Plan
CAA section 175A provides the general framework for a maintenance
plan. We interpret this section of the Act to require, in general, the
following core elements: attainment inventory, maintenance
demonstration, monitoring network, verification of continued
attainment, and contingency plan.\26\ Under CAA section 175A, a
maintenance plan must demonstrate continued attainment of the
applicable NAAQS for at least ten years after the EPA approves a
redesignation to attainment. Eight years after redesignation, the State
must submit a revised maintenance plan that demonstrates continued
attainment for the subsequent ten-year period following the initial
ten-year maintenance period. To address the possibility of future NAAQS
violations, the maintenance plan must contain such contingency
provisions that the EPA deems necessary to promptly correct any
violation of the NAAQS that occurs after redesignation of the area.
---------------------------------------------------------------------------
\26\ Memorandum dated September 4, 1992, from John Calcagni,
Director, EPA Air Quality Management Division, to Regional Office
Air Division Directors, Subject: Procedures for Processing Requests
to Redesignate Areas to Attainment (``Calcagni Memo''), pages 8
through 13.
---------------------------------------------------------------------------
The primary guidance on maintenance plans and redesignation
requests is a September 4, 1992 memorandum from John Calcagni, titled
``Procedures for Processing Requests to Redesignate Areas to
Attainment'' (``Calcagni Memo''). The Calcagni Memo outlines the key
elements of a maintenance plan, which include verification of continued
attainment, monitoring network requirements, attainment emissions
inventory, maintenance demonstration, and a contingency plan. We
evaluate maintenance plans based on the satisfactory fulfillment of
these and all relevant procedural requirements of the CAA.
Based on our review and evaluation of the Plan, as detailed below,
we are proposing to approve the Truckee Meadows Second PM<INF>10</INF>
Maintenance Plan submittal because we believe that it meets the
requirements of CAA section 175A.
[[Page 62375]]
A. Emissions Inventory
A maintenance plan for the PM<INF>10</INF> NAAQS should include an
inventory of emissions of PM<INF>10</INF> in the area that identifies a
level of emissions sufficient to attain the PM<INF>10</INF> NAAQS.\27\
This inventory should be consistent with the EPA's most recent guidance
on emissions inventories for nonattainment areas available at the time
and represent emissions during the time period associated with the
monitoring data showing attainment, in this case, 2017 through 2019.
The inventory should also be comprehensive, including emissions from
stationary sources, area sources, nonroad mobile sources, and on-road
mobile sources, and be based on actual emissions during the appropriate
season or episode, if applicable.\28\ The specific PM<INF>10</INF>
emissions inventory requirements are set forth in the Air Emissions
Reporting Requirements rule (AERR).\29\ The EPA has provided additional
guidance for developing PM<INF>10</INF> emissions inventories in
``PM<INF>10</INF> Emissions Inventory Requirements,'' \30\ and
``Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and
Regional Haze,'' (May 2017).
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\27\ Calcagni Memo, pages 8 through 9.
\28\ CAA section 172(c)(3).
\29\ 40 CFR part 51, subpart A.
\30\ EPA-454/R-94-033, September 1994.
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The Truckee Meadows Second PM<INF>10</INF> Maintenance Plan
provides an attainment emissions inventory of actual emissions from all
sources of direct PM<INF>10</INF> within the Truckee Meadows area,
based on the 2017 National Emissions Inventory (NEI),\31\ adjusted
using seasonal adjustment factors. Updated methodologies and emissions
factors were applied to the residential wood combustion and unpaved
roads categories to ensure accuracy.\32\ Table 3 of this document
summarizes the 2017 attainment inventory provided in the Truckee
Meadows Second PM<INF>10</INF> Maintenance Plan.
---------------------------------------------------------------------------
\31\ Because the most recent NEI year (2020) available during
plan development was affected by disruptions caused by the COVID-19
pandemic and is therefore not representative of normal conditions,
NNPH determined it should not be used and instead relied on the 2017
emissions inventory. Truckee Meadows Second PM<INF>10</INF>
Maintenance Plan, page 6.
\32\ Truckee Meadows Second PM<INF>10</INF> Maintenance Plan,
appendices C and E.
Table 3--Truckee Meadows 2017 Seasonal Emissions Inventory for Direct PM10
[Pounds (lbs)/day]
----------------------------------------------------------------------------------------------------------------
Estimated Maintenance
Category Subcategory actual plan baseline
emissions \a\
----------------------------------------------------------------------------------------------------------------
Point......................................... All............................. 43 43
Nonpoint...................................... Stationary Source Fuel 3,486 3,486
Combustion, including
Residential Wood Combustion.
Industrial Processes............ 2,174 2,174
Other Solvent Utilization....... 3 3
Misc. Non-Point Sources, 2,641 2,641
Excluding Wildfires.
Wildfires....................... 26 21
Non-Road Mobile............................... ................................ 743 743
On-Road Mobile................................ ................................ 954 954
-----------------------------------------------------------------
Total \b\................................. ................................ 10,070 10,065
----------------------------------------------------------------------------------------------------------------
\a\ Represents maintenance conditions.
\b\ Totals may not add up due to rounding.
Source: Truckee Meadows Maintenance Plan, Appendix B, Table B-1.
In addition to showing the estimated actual emissions in 2017,
Table 3 of this document shows the baseline emissions inventory used to
demonstrate maintenance through 2036. The only difference between the
2017 actual emissions and the maintenance plan baseline emissions is in
the wildfire source category. Table 3 of the Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan lists wildfire emissions inventories
from NEI years from 1999 through 2020. The Truckee Meadows area
experienced unusually high smoke impacts from wildfires in 2011, 2014,
and 2020. For the purposes of developing a baseline attainment
inventory for demonstrating ongoing attainment, NNPH replaced the
actual PM<INF>10</INF> emissions from wildfires in 2017 (26 lbs/day)
with the average of wildfire emissions from previous typical years
(1999, 2002, 2005, and 2008) (21 lbs/day). The difference between 26
lbs/day and 21 lbs/day represents 0.06 percent of the non-point source
emissions inventory. NNPH notes that future year planning should not be
driven by wildfire emissions, and that PM<INF>10</INF> exceedances and
violations caused by natural events (e.g., wildfires) will be treated
as exceptional events.\33\ We find this adjustment to be reasonable.
---------------------------------------------------------------------------
\33\ Id., page 9.
---------------------------------------------------------------------------
Information regarding the development of the emissions inventories,
such as the methodology NNPH uses to develop growth factors for future-
year inventories for stationary and mobile sources, is included in
appendices A through F of the Plan.
The Plan does not provide emissions inventories for precursors to
PM<INF>10</INF> and instead addresses direct PM<INF>10</INF> only. NNPH
notes that precursor emissions were ``determined to be negligible in
the First 10-Year Maintenance Plan, in reference to the 2011 emissions
inventory'' on which the plan was based.\34\ In its approval of the
first maintenance plan, the EPA concluded that the absence of
PM<INF>10</INF> precursors from the attainment inventory was
acceptable.\35\
---------------------------------------------------------------------------
\34\ Id., pages 6 through 7.
\35\ In its proposed approval of the first maintenance plan, the
EPA concluded that the absence of PM<INF>10</INF> precursors from
the attainment inventory was acceptable. This determination was
based on a 1998 technical study conducted by the Desert Research
Institute and current inventory and monitoring data. 80 FR 58640,
58649 (September 30, 2015).
---------------------------------------------------------------------------
In support of continuing this approach, NNPH asserts that there
have not been any substantial changes in the emissions inventory or new
major sources of volatile organic compounds (VOCs), nitrogen oxides
(NO<INF>X</INF>), and sulfur oxides (SO<INF>X</INF>) within the
maintenance area since 2011 and notes that the control strategy for
maintaining compliance with the NAAQS relies on
[[Page 62376]]
control of direct PM<INF>10</INF>.\36\ The NNPH also states that
sources of precursor emissions are not correlated with reductions in
PM<INF>10</INF> emissions and ambient concentrations of
PM<INF>10</INF>.\37\
---------------------------------------------------------------------------
\36\ Truckee Meadows Second PM<INF>10</INF> Maintenance Plan,
pages 6 through 7.
\37\ Id., page 7.
---------------------------------------------------------------------------
The EPA believes that the selection of 2017 as the attainment year
inventory is appropriate given that it represents emissions from an
attainment year and it is the most recent emissions inventory
representative of normal conditions available at the time of
preparation of the maintenance plan. Moreover, preparation of a
seasonal (winter) inventory in this instance is appropriate given that
winter is typically the season when the highest ambient PM<INF>10</INF>
concentrations are monitored in the Truckee Meadows. We find that
NNPH's 2017 emissions inventory for direct PM<INF>10</INF> is based on
reasonable assumptions and methodologies, as described in the Truckee
Meadows Second PM<INF>10</INF> Maintenance Plan and 2017 Periodic
Emissions Inventory,\38\ and that the inventory is comprehensive,
current, and accurate. We therefore propose to approve the inventory of
actual emissions in 2017 as meeting the requirements of CAA section
172(c)(3) and find the 2017 inventory, as adjusted for wildfire
emissions, acceptable for use in demonstrating maintenance of the
PM<INF>10</INF> standard in the future.
---------------------------------------------------------------------------
\38\ NNPH's 2017 Periodic Emissions Inventory, submitted to the
EPA for purposes of meeting the AERR requirements, provides
significant detail regarding the assumptions and methodologies used
to develop the 2017 p.m.<INF>10</INF> emissions inventory used in
the Truckee Meadows Second 10-Year Maintenance Plan. The 2017
Periodic Emissions Inventory also includes emissions inventories for
VOCs, NO<INF>X</INF>, SO<INF>X</INF>, and ammonia. The AERR requires
State, local, and Tribal air agencies to collect and submit emission
data for criteria pollutants into the EPA's Emissions Inventory
System.
---------------------------------------------------------------------------
B. Maintenance Demonstration
CAA section 175A(a) requires that the maintenance plan provide for
maintenance of the NAAQS for at least 10 years after redesignation. A
State may generally demonstrate maintenance of the NAAQS by either
showing that future emissions of a pollutant or its precursors will not
exceed the level of the attainment inventory, or by conducting modeling
that shows that the future mix of sources and emissions rates will not
cause a violation of the NAAQS.\39\
The Truckee Meadows Second PM<INF>10</INF> Maintenance Plan
demonstrates that the Truckee Meadows area will maintain the
PM<INF>10</INF> NAAQS by comparing the adjusted 2017 attainment
inventory (also referred to as the maintenance plan baseline) against
the projected emissions for 2025, 2030, and 2040.\40\ NNPH demonstrates
continued maintenance of the PM<INF>10</INF> NAAQS by showing that
future emissions of PM<INF>10</INF> will not exceed the level of the
2017 maintenance year baseline. Using the adjusted 2017 emissions
inventory as a baseline and appropriate growth and control factors
described in Appendix A, ``Growth Factors for Emissions Projections'',
and Table A-1 of the Truckee Meadows Second PM<INF>10</INF> Maintenance
Plan, NNPH projected emissions inventories for 2020, 2025, 2030, and
2040. Source specific growth factors were developed based on various
demographic, climate, and other data projections. Control factors were
developed based on historic data and reasonable assumptions.
Despite expected growth in the area, the Plan's projected future
PM<INF>10</INF> emissions in the Truckee Meadows area are below the
2017 maintenance inventory of 10,064 lbs/day.\41\ The downward trend in
total expected emissions is due to federally enforceable
PM<INF>10</INF> control programs targeting mobile sources and
residential wood combustion. Table 4 of this document illustrates that
while there are some increases in point source and on-road mobile
source emissions, declining emissions from non-road mobile and nonpoint
source categories drive a decrease in overall PM<INF>10</INF> emissions
through 2040. As discussed in section IV.D of this document, NNPH has
chosen to include ``safety margins'' in the motor vehicle emissions
budgets for 2025 (857 lbs/day), 2030 (904 lbs/day), and 2040 (1,173
lbs/day).\42\ We find that the overall emissions projections, including
the safety margins, continue to demonstrate maintenance because they do
not exceed the emissions in 2017. Therefore, the safety margins are
consistent with maintenance through 2036.
Table 4--Truckee Meadows PM10 Maintenance Area Emissions Projections
[Lbs per typical PM10 Season Day]
----------------------------------------------------------------------------------------------------------------
2017 \a\
Category Maintenance 2025 2030 2040
plan baseline
----------------------------------------------------------------------------------------------------------------
Point Sources................................... 43 41 57 69
Nonpoint Sources................................ 8,324 8,202 8,140 7,824
Non-Road Mobile................................. 743 321 299 274
On-Road Mobile.................................. 954 643 665 706
Total \b\....................................... 10,064 9,207 9,160 8,891
Motor Vehicle Emissions Budget Safety Margin.... .............. 857 904 1,173
10,064 10,064 10,064 10,064
----------------------------------------------------------------------------------------------------------------
Source: Truckee Meadows Maintenance Plan, Table 5 and Table 7.
\a\ Represents maintenance conditions.
\b\ Totals may not add up due to rounding.
CAA section 175A(b) requires that eight years after redesignation,
the State must submit to EPA an additional revision of the SIP for
maintaining the NAAQS for an additional 10 years after the expiration
of the first 10-year maintenance plan, in this case, until 2036. The
projected emissions inventories for 2025, 2030, and 2040 sufficiently
demonstrate that the Truckee Meadows area will continue to maintain the
PM<INF>10</INF> standard throughout the second 10-year maintenance
period. The EPA therefore concludes that the Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan demonstrates maintenance of the
standard through 2036.
---------------------------------------------------------------------------
\39\ Calcagni Memo, pages 9 through 11.
\40\ Table B-1 of Appendix B of the Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan provides PM<INF>10</INF> emissions
for the 2017 maintenance year baseline and the projected inventories
for 2025, 2030, and 2040.
\41\ Id.
\42\ Id., page 13.
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[[Page 62377]]
C. PM10 Air Quality Monitoring Network
After an area has been redesignated, the State should continue to
operate an appropriate air quality monitoring network, in accordance
with 40 CFR part 58, to verify the attainment status of the area.\43\
NNPH monitors ambient PM<INF>10</INF> concentrations through a network
of three State and local air monitors (SLAMS) in the Truckee Meadows
area. The network is reviewed annually under 40 CFR 58.20(d) to ensure
it continues to meet the applicable monitoring objectives. The
currently active network monitors are listed in Table 5 of this
document.\44\ The EPA approved NNPH's air quality network plan for 2025
on December 5, 2025.\45\ The approved plan and the EPA approval letter
are included in the docket for this proposed action.
---------------------------------------------------------------------------
\43\ Calcagni Memo, page 11.
\44\ Section I.C of this document contains a discussion of
monitoring results during the first 10-year maintenance period.
\45\ Letter from Dena Vallano, Manager, Monitoring and Analysis
Section, EPA Regin 9, to Francisco Vega, Director, Air Quality
Management Division, NNPH, dated December 5, 2025.
Table 5--Truckee Meadows PM10 Monitors
------------------------------------------------------------------------
Site name Site ID Street address
------------------------------------------------------------------------
Toll.......................... 32-031-0025 684A State Route 341,
Reno, NV.
Reno 4........................ 32-031-0031 1260-A Stewart St.,
Reno, NV.
Sparks........................ 32-031-1005 750 4th St, Sparks,
NV.
------------------------------------------------------------------------
Source: Annual Network Plan, Northern Nevada Public Health, June 24,
2025.
In the Truckee Meadows Second PM<INF>10</INF> Maintenance Plan, the
NNPH commits to continue to operate and maintain a PM<INF>10</INF>
ambient air quality monitor in the planning area, in accordance with 40
CFR part 58, to verify attainment of the PM<INF>10</INF> NAAQS within
the Truckee Meadows area. Data collected by the monitoring network are
also used to implement the contingency measures trigger calculation,
discussed in section IV.E. of this proposed action. We propose that the
Second PM<INF>10</INF> Maintenance Plan contains adequate provisions
for continued ambient PM<INF>10</INF> monitoring to verify continued
attainment through the full maintenance period.
D. Verification of Continued Attainment
Once an area has been redesignated, the State should continue to
operate an appropriate air quality monitoring network, in accordance
with 40 CFR part 58, to verify the continued attainment status of the
area.\46\ As discussed in section IV.C of this document, NNPH monitors
ambient concentrations of PM<INF>10</INF> in the Truckee Meadows
planning area at three separate monitoring stations. NNPH indicates its
intention to continue operation of the air quality monitoring network
in accordance with 40 CFR part 58 to verify the attainment status of
the area. The NNPH notes that the monitoring network will be reviewed
annually to ensure the network meets all relevant monitoring
requirements defined in 40 CFR part 58.\47\
---------------------------------------------------------------------------
\46\ Calcagni Memo, page 11.
\47\ Annual Network Plan, Northern Nevada Public Health, June
24, 2025.
---------------------------------------------------------------------------
In addition to continued air monitoring, NNPH describes its
tracking of actual emissions through periodic emissions inventories and
commits to continuing to comply with the rules governing these
emissions reporting requirements. Finally, NNPH describes various
control strategies and enforcement actions that will ensure continued
verification of attainment and maintenance of the PM<INF>10</INF>
NAAQS.\48\ We are proposing to determine that these efforts are
sufficient to verify continued attainment through the maintenance
period.
---------------------------------------------------------------------------
\48\ Truckee Meadows Second PM<INF>10</INF> Maintenance Plan,
pages 20 through 21.
---------------------------------------------------------------------------
E. Contingency Provisions
CAA section 175A(d) requires that maintenance plans include
contingency provisions, as the EPA deems necessary, to promptly correct
any violations of the NAAQS that occur after the redesignation of the
area. Such provisions must include a requirement that the State will
implement all measures with respect to the control of the relevant air
pollutants that were contained in the SIP for the area before
redesignation of the area as an attainment area.
Under CAA section 175A(d), contingency measures identified in the
contingency plan do not have to be fully adopted at the time of
redesignation. However, the contingency plan is an enforceable part of
the SIP and should ensure that the contingency measures are adopted
expeditiously once they are triggered by a specified event. The
maintenance plan should clearly identify the measures to be adopted, a
schedule and procedure for adoption and implementation, and a specific
timeline for action by the State. In addition, the State should
identify the specific indicators or triggers that will be used to
determine when the contingency measures need to be implemented.
The NNPH has adopted a contingency plan to address possible future
PM<INF>10</INF> air quality problems in the Truckee Meadows area. As
noted by NNPH, contingency measures are to be triggered to promptly
correct any violation of the standard that occurs during the
maintenance period. The contingency plan for the Truckee Meadows area
will be triggered when the number of exceedances recorded at a monitor,
averaged over three consecutive years, is greater than 1.05.\49\ The
contingency plan also includes a screening process that allows NNPH,
subject to EPA review and agreement, to exclude certain exceedances
from the contingency measure trigger calculation (CMTC) if the agencies
agree that the information developed by the NNPH, through its AQMD, is
sufficient to support exclusion.
---------------------------------------------------------------------------
\49\ Id., page 21.
---------------------------------------------------------------------------
The purpose of the screening process is to differentiate between
exceedances that are not within the NNPH's control (i.e., exceedances
that occur despite the implementation of reasonable measures), and
exceedances that are within the NNPH's or State's control and therefore
should be included in the trigger calculation. Should the EPA agree
with NNPH's exclusion of an exceedance from the CMTC using this
process, it would not constitute the EPA's concurrence that the
exceedance was caused by an exceptional event. The exceedance would
therefore continue to be included in design value calculations for the
planning area, unless the State, following opportunity for public
comment, submits a request for the EPA to concur on the exceedance as
an exceptional event pursuant to 40 CFR 50.14, and the EPA reviews the
submittal and formally concurs.
[[Page 62378]]
Under the contingency trigger screening process described in the
Plan, the NNPH will analyze any exceedance(s) that leads to a violation
of the NAAQS on a quarterly basis. Using the screening criteria set
forth in the plan, NNPH will evaluate exceedances to determine if any
exceedances qualify for exclusion from the CMTC.\50\ If the NNPH
believes an exceedance should be excluded, it will submit an exclusion
request to the EPA within 90 days of the end of the calendar quarter.
---------------------------------------------------------------------------
\50\ The Plan (pages 22 through 24) includes criteria for high
wind dust events and wildfire events that would be used to determine
if an exceedance should be excluded from the contingency plan
trigger calculation.
---------------------------------------------------------------------------
If the EPA reviews and agrees with the exclusion request, NNPH can
exclude that exceedance from the CMTC. If the EPA rejects the request
and NNPH disagrees with the EPA's determination, it can submit an
exceptional events demonstration. Due to the need to promptly address
violations, NNPH will proceed with the contingency process while the
exceptional event process is under way. NNPH will make recommendations,
including a timeline for adoption and implementation of measures, to
the DBOH within 45 days of reaching the trigger level, with the
exceedance in question included in the CMTC.\51\ Contingency measures
should be adopted by the DBOH and implemented as expediently as
possible, prior to the next PM<INF>10</INF> season.\52\
---------------------------------------------------------------------------
\51\ Id., page 22.
\52\ Id., page 24.
---------------------------------------------------------------------------
The Truckee Meadows Second PM<INF>10</INF> Maintenance Plan
includes a list of the source categories that typically contribute
significantly to PM<INF>10</INF> season emissions along with potential
contingency measures applicable to each category.\53\ The list of
categories includes paved and unpaved roads, dust control, residential
wood combustion, and mobile sources of diesel emissions.
---------------------------------------------------------------------------
\53\ Id., Table 11.
---------------------------------------------------------------------------
Based on our review of the Truckee Meadows Second PM<INF>10</INF>
Maintenance Plan, we propose to find that the contingency provisions of
the Plan clearly identify potential contingency measures, contain a
triggering mechanism to determine when contingency measures are needed,
contain a description of the process of recommending and implementing
contingency measures, and contain specific and appropriate timelines
for action. We also propose to find that the contingency trigger
screening process, including the associated EPA review, is reasonably
designed to distinguish between exceedances that were not within the
NNPH or State control, and exceedances that were within the NNPH or
State control and for which new or tightened control measures might be
effective. Thus, we propose to conclude that the contingency plan in
the Plan is adequate to ensure correction of any violation of the
PM<INF>10</INF> NAAQS that occurs after redesignation, as required by
CAA section 175A(d).
F. Motor Vehicle Emissions Budgets for Transportation Conformity
CAA section 176(c) 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 expeditious attainment of the standards. Conformity to the
SIP's goals means that such actions will not: (1) cause or contribute
to violations of a NAAQS, (2) worsen the severity of an existing
violation, or (3) delay timely attainment of any NAAQS or any interim
milestone.
Actions involving Federal Highway Administration (FHWA) or Federal
Transit Administration (FTA) funding or approval are subject to the
EPA's transportation conformity rule, codified at 40 CFR part 93,
subpart A. Under this rule, metropolitan planning organizations in
nonattainment and maintenance areas coordinate with State and local air
quality and transportation agencies, the EPA, FHWA, and FTA to
demonstrate that an area's regional transportation plans and
transportation improvement programs conform to the applicable SIP. This
demonstration is typically accomplished by showing that estimated
emissions from existing and planned highway and transit systems are
less than or equal to the motor vehicle emissions budgets (``budgets'')
contained in submitted or approved control strategy plans or
maintenance plans.
Control strategy SIPs and maintenance plans typically establish
budgets for criteria pollutants and precursors to address pollution
from on-road vehicles such as cars and trucks.\54\ Budgets are
generally established for specific years for the relevant pollutants or
precursors. PM<INF>10</INF> maintenance plan submittals must identify
budgets for transportation-related PM<INF>10</INF> emissions in the
last year of the maintenance period.\55\ Budgets may also be specified
for additional years during the maintenance period.
---------------------------------------------------------------------------
\54\ Transportation-related emissions of VOC or NO<INF>X</INF>
must also be specified in PM<INF>10</INF> areas if the EPA or the
State find that transportation-related emissions of one or both of
these precursors within the nonattainment area are a significant
contributor to the PM<INF>10</INF> nonattainment problem and has so
notified the metropolitan planning organization and the U.S.
Department of Transportation, or the applicable SIP revision or SIP
revision submittal establishes an approved or adequate budget for
such emissions as part of the reasonable further progress,
attainment, or maintenance strategy. 40 CFR 93.102(b)(2)(iii).
\55\ See 40 CFR 93.118(b)(2).
---------------------------------------------------------------------------
For budgets in a maintenance plan to be approvable, they must meet,
at a minimum, the EPA's adequacy criteria.\56\ To meet these
requirements, the budgets must be consistent, when considered with
emissions from all other sources, with maintenance of the NAAQS and
reflect all of the motor vehicle control measures relied upon for the
maintenance demonstration.
---------------------------------------------------------------------------
\56\ 40 CFR 93.118(e)(4).
---------------------------------------------------------------------------
The EPA also determines the adequacy of budgets in certain
submitted SIPs. The adequacy process is separate from the approval
process. 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 budgets during a public comment period; and (3) making a finding of
adequacy or inadequacy. The process for determining the adequacy of a
submitted budget is codified at 40 CFR 93.118(f). The EPA can notify
the public by either posting an announcement that the EPA has received
SIP budgets on the EPA's adequacy website \57\ or via a Federal
Register notice of proposed rulemaking when the EPA reviews the
adequacy of a maintenance plan budget simultaneously with its review
and action on the SIP submittal itself.\58\
---------------------------------------------------------------------------
\57\ 40 CFR 93.118(f)(1).
\58\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------
The Truckee Meadows Second PM<INF>10</INF> Maintenance Plan
provides budgets, which include PM<INF>10</INF> emissions estimates for
transportation-related emissions and a safety margin, for direct
PM<INF>10</INF> for 2025, 2030, and 2040.\59\ Transportation-related
emissions include emissions from on-road vehicles, road construction,
and re-entrained paved and unpaved road dust.\60\ The difference
between the transportation-related emissions estimates in the projected
emissions inventory and the budgets is defined as a safety margin.\61\
[[Page 62379]]
The transportation-related emissions and safety margins represent a
level of emissions consistent with attainment of the PM<INF>10</INF>
NAAQS.\62\ The applicable PM<INF>10</INF> budgets for the Truckee
Meadows area are presented in Table 6 of this document.
---------------------------------------------------------------------------
\59\ Truckee Meadows PM<INF>10</INF> Maintenance Plan, page 12.
The previously EPA-approved budgets for 2025 and 2030 are being
replaced by revised budgets that reflect updates to emissions
models, emissions methodologies, and planning assumptions. Id., page
13.
\60\ Id., Table 7.
\61\ 40 CFR 93.101. A safety margin is 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
requirement for reasonable further progress, attainment, or
maintenance.
\62\ Truckee Meadows Second PM<INF>10</INF> Maintenance Plan,
Table 7.
Table 6--Proposed PM10 Motor Vehicle Emissions Budgets for Truckee Meadows
[Lbs/day]
----------------------------------------------------------------------------------------------------------------
Transportation-
Budget year related emissions Safety margin PM10 budgets
----------------------------------------------------------------------------------------------------------------
2025................................................... 3,405 857 4,262
2030................................................... 3,457 904 4,361
2040................................................... 3,436 1,173 4,609
----------------------------------------------------------------------------------------------------------------
Source: Truckee Meadows Second PM10 Maintenance Plan, Table 7.
While transportation conformity is typically not required after the
completion of the 20-year maintenance period, which ends in 2036, NNPH
has chosen to provide a budget for 2040. If approved, conformity will
continue to apply in the Truckee Meadows area through 2040.\63\
---------------------------------------------------------------------------
\63\ See 73 FR 4420, 4434-4435 (Jan. 24, 2008) and EPA's
``Transportation Conformity Guidance for Areas Reaching the End of
the Maintenance Period.'' If a maintenance plan establishes a budget
for a year that is more than 20 years beyond the effective date of
the EPA's approval of the area's redesignation request and
maintenance plan, conformity continues to apply until that budget
year, ending on the month and day of that maintenance plan's
effective date.
---------------------------------------------------------------------------
NNPH consulted with Federal, State, and local agencies during the
development of the budgets.\64\ NNPH used the EPA's Motor Vehicle
Emissions Simulator (MOVES2014b) to develop on-road and non-road mobile
source emissions estimates for the 2017 emissions inventory.\65\ On-
road mobile source emissions were modeled for 2025, 2030, and 2040
using MOVES3,\66\ incorporating the most recent planning assumptions
for the transportation network.
---------------------------------------------------------------------------
\64\ The Air Quality Interagency Consultation Group, which meets
quarterly, includes representatives from the EPA, the FHWA, the
Nevada Department of Transportation, and Regional Transportation
Commission of Washoe County, Nevada.
\65\ Truckee Meadows Second PM<INF>10</INF> Maintenance Plan.
pages 6 through 7. NNPH began development of this plan before the
MOVES3 emissions model was made available by the EPA on January 7,
2021 (86 FR 1106). Therefore, at the time of base year on-road
inventory development, MOVES2014b was the latest emissions model
available, per 40 CFR 93.111.
\66\ Truckee Meadows Second PM<INF>10</INF> Maintenance Plan.
pages 6 through 7.
---------------------------------------------------------------------------
The EPA evaluated the budgets against our adequacy criteria in 40
CFR 93.118(e)(4) and (5) as part of our review of the budget's
approvability. While adequacy and approval are two separate actions,
reviewing the budgets in terms of the adequacy criteria informs the
EPA's decision to propose to approve the budgets. We have completed our
detailed review of the Truckee Meadows Second PM<INF>10</INF>
Maintenance Plan and are proposing herein to approve the Plan including
the demonstration of maintenance of the PM<INF>10</INF> NAAQS in the
area through the year 2036. We have also reviewed the budgets in the
Plan and found that they are consistent with the maintenance
demonstration for which we are proposing approval, are clearly
identified and precisely quantified, 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 93.118(e)(4) and (5).\67\ For these
reasons, the EPA proposes to approve the 2025, 2030, and 2040 budgets
in the Truckee Meadows Second PM<INF>10</INF> Maintenance Plan.
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\67\ The EPA's adequacy checklist can be found within the docket
for this proposed rulemaking.
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In addition, in this document the EPA is announcing the beginning
of the adequacy process for these budgets. Under the transportation
conformity regulation, the EPA can begin this process with our proposed
action on the second maintenance plan.\68\ The public has 30 days to
comment on the adequacy of the budgets, per the transportation
conformity rule at 40 CFR 93.118(f)(2)(i) and (ii). Any comments on the
adequacy of the budgets should be submitted to the docket for this
proposed rulemaking.
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\68\ See 40 CFR 93.118(f)(2).
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If the EPA issues a final rulemaking action to approve the budgets,
they will be effective on the date of the publication date of the EPA's
final rulemaking in the Federal Register.\69\ The approved budgets must
be used by the Regional Transportation Commission of Washoe County in
future transportation conformity determinations for Truckee Meadows for
the PM<INF>10</INF> NAAQS.
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\69\ 40 CFR 93.118(f)(2)(iii).
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V. Proposed Action and Request for Public Comment
Under CAA section 110(k)(3), and for the reasons set forth in this
document, the EPA is proposing to approve the Truckee Meadows Second
PM<INF>10</INF> Maintenance Plan submitted by NDEP on March 12, 2026,
as a revision to the Nevada SIP. We are proposing to approve the
maintenance demonstration and contingency provisions as meeting all
applicable requirements for maintenance plans and related contingency
provisions in CAA section 175A, and the budgets for 2025, 2030, and
2040 for transportation conformity purposes as we find they meet all
applicable criteria for such budgets including the adequacy criteria
under 40 CFR 93.118(e).
We are soliciting comments on these proposed actions. We will
accept comments from the public for 30 days following publication of
this proposal in the Federal Register and will consider any relevant
comments before taking final action.
VI. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve State choices,
provided that they meet the criteria of the CAA. Accordingly, this
proposed action merely proposes to approve State law as meeting Federal
requirements and does not impose additional requirements beyond those
imposed by State law. For that reason, this proposed action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under
[[Page 62380]]
Executive Order 12866 (58 FR 51735, October 4, 1993);
<bullet> Is not an Executive Order 14192 (90 FR 9065, February 6,
2025) regulatory action because this action is not significant under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> 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.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L.104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it proposes to approve a State program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA.
The Reno-Sparks Indian Colony, a federally recognized Tribe, has
reservation lands located within the boundaries of the Truckee Meadows
PM<INF>10</INF> maintenance area. This proposal, if finalized, will not
change the designation or classification of the maintenance area,
including areas of Indian country within the maintenance area.
Additionally, it will neither impose substantial direct compliance
costs on federally recognized Tribal governments, nor preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000). The EPA will notify the Tribe about this proposal.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Nitrogen dioxide, Particulate Matter, Sulfur Dioxide,
Reporting and recordkeeping requirements, Volatile organic compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: September 18, 2026.
Michael Martucci,
Acting Regional Administrator, Region IX.
[FR Doc. 2026-20102 Filed 9-30-26; 8:45 am]
BILLING CODE 6560-50-P
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</html>Indexed from Federal Register on October 1, 2026.
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