Proposed Rule2026-18755
Clean Data Determination; 1997 8-Hour Ozone Standards; California; Sacramento Metro Area
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
September 14, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The U.S. Environmental Protection Agency (EPA or "Agency") is proposing to issue a clean data determination (CDD) for the Sacramento Metro, California nonattainment area to reflect our finding that the area is attaining the 1997 8-hour ozone national ambient air quality standards (NAAQS or "standards"). This finding is based on quality-assured and certified ambient air quality monitoring data from 2023 through 2025. If we finalize this CDD, certain Clean Air Act (CAA) requirements that apply to the Sacramento Metro area will be suspended for so long as the area continues to attain the 1997 8-hour ozone NAAQS. 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 176 (Monday, September 14, 2026)</title>
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[Federal Register Volume 91, Number 176 (Monday, September 14, 2026)]
[Proposed Rules]
[Pages 58046-58052]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-18755]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2026-4885; FRL-13450-01-R9]
Clean Data Determination; 1997 8-Hour Ozone Standards;
California; Sacramento Metro Area
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed determination.
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SUMMARY: The U.S. Environmental Protection Agency (EPA or ``Agency'')
is proposing to issue a clean data determination (CDD) for the
Sacramento Metro, California nonattainment area to reflect our finding
that the area is attaining the 1997 8-hour ozone national ambient air
quality standards (NAAQS or ``standards''). This finding is based on
quality-assured and certified ambient air quality monitoring data from
2023 through 2025. If we finalize this CDD, certain Clean Air Act (CAA)
requirements that apply to the Sacramento Metro area will be suspended
for so long as the area continues to attain the 1997 8-hour ozone
NAAQS. We are taking comments on this proposal and plan to follow with
a final action.
DATES: Comments must be received on or before October 14, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2026-4885 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: Nicole Law, EPA Region IX, 75
Hawthorne Street, San Francisco, CA 94105; telephone number: (415) 947-
4126; email: <a href="/cdn-cgi/l/email-protection#f79b9680d9999e94989b92b7928796d9909881"><span class="__cf_email__" data-cfemail="7f131e085111161c10131a3f1a0f1e51181009">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this proposed rule, the use of
``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We use
multiple abbreviations and terms in this proposed rule. While this list
may not be exhaustive, for ease of reading and for reference purposes,
the EPA defines the following terms and acronyms here:
AQS--Air Quality System
CAA--Clean Air Act
CARB--California Air Resources Board
CBI--confidential business information
CDD--clean data determination
CFR--Code of Federal Regulations
EDCAQMD--El Dorado County Air Quality Management District
EPA--Environmental Protection Agency
FR--Federal Register
FRAQMD--Feather River Air Quality Management District
NAAQS--national ambient air quality standards
NO<INF>X</INF>--nitrogen oxides
NSR--New Source Review
NTTA--National Technology Transfer and Advancement Act
OMB--Office of Management and Budget
PCAPCD--Placer County Air Pollution Control District
ppm--parts per million
PRA--Paperwork Reduction Act
RACM--reasonably available control measures
RFP--reasonable further progress
RFA--Regulatory Flexibility Act
SIP--state implementation plan
SLAMS--State and local air monitoring stations
SMAQMD--Sacramento Metropolitan Air Quality Management District
SRR--SIP Requirements Rule
TSA--technical systems audit
UMRA--Unfunded Mandates Reform Act
U.S.C.--United States Code
VOC--volatile organic compounds
YSAQMD--Yolo-Solano Air Quality Management District
Table of Contents
I. Executive Summary
A. What action is the EPA proposing to take?
B. What is the legal authority and what are the requirements?
II. Background
A. Ozone NAAQS
B. Sacramento Ozone Designations, Classifications, and SIP
Revisions
C. The EPA's Clean Data Policy
III. The EPA's Analysis
A. Applicable Statutory and Regulatory Provisions
B. Clean Data Determination
C. Monitoring Network Considerations
D. Data Considerations
E. Effects of This Proposed Determination
IV. The EPA's Proposed Action
V. Statutory and Executive Order Reviews
I. Executive Summary
A. What action is the EPA proposing to take?
The EPA is proposing to issue a CDD for the Sacramento Metro,
California nonattainment area to reflect our finding that the area is
attaining the 1997 8-hour ozone NAAQS. This finding is based on
quality-assured and certified ambient air quality monitoring data from
2023 through 2025.
B. What is the legal authority and what are the requirements?
Under the EPA's longstanding Clean Data Policy,\1\ which is
reaffirmed for the 1997 ozone NAAQS at 40 CFR 51.918, when an area has
attained the relevant 8-hour ozone standards, the Agency may issue a
CDD after notice and comment rulemaking determining that a specific
area is attaining the relevant standards. Under EPA regulations at 40
CFR 50.10, an area attains the 1997 ozone NAAQS when the 3-year average
[[Page 58047]]
of the annual fourth-highest daily maximum 8-hour average ozone
concentration is less than or equal to 0.08 parts per million (ppm) at
each eligible monitoring site within the area.
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\1\ Memorandum dated May 10, 1995, from John S. Seitz, Director,
Office of Air Quality Planning and Standards, to Regional Office Air
Division Directors, Regions 1-10, Subject: ``Reasonable Further
Progress, Attainment Demonstration, and Related Requirements for
Ozone Nonattainment areas Meeting the Ozone National Ambient Air
Quality Standard'' (``1995 Seitz Memo'').
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II. Background
A. Ozone NAAQS
Ground-level ozone is formed when nitrogen oxides (NO<INF>X</INF>)
and volatile organic compounds (VOC) react in the presence of
sunlight.\2\ These two pollutants, referred to as ozone precursors, are
emitted by many types of pollution 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.
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\2\ The State of California uses the term Reactive Organic Gases
(ROG) rather than VOC in some of its ozone-related SIP submissions.
As a practical matter, ROG and VOC refer to the same set of chemical
constituents and for simplicity, we refer to this set of gases as
VOC.
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Health effects associated with exposure to ground-level ozone
include reduced lung function; reduced ability to breathe as deeply and
vigorously as normal; irritated airways, coughing, or a sore or
scratchy throat; pain when taking a deep breath and shortness of
breath; increased frequency of asthma attacks; inflammation of and
damage to the lining of the lung; increased susceptibility to
respiratory infection; and aggravation of chronic lung diseases such as
asthma, emphysema, and bronchitis. Ozone may continue to cause lung
damage even when the symptoms have disappeared, and breathing ozone may
contribute to premature death, especially in people with heart and lung
disease.\3\
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\3\ EPA, ``Fact Sheet, Final Revisions to the National Ambient
Air Quality Standards for Ozone,'' Mar. 2008.
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Under CAA section 109, the EPA promulgates NAAQS for pervasive air
pollutants, such as ozone. The NAAQS establish concentration levels
whose attainment and maintenance the EPA has determined to be requisite
to protect public health and welfare. In 1979, the EPA established
primary (public health-based) and secondary (welfare-based) NAAQS for
ozone at 0.12 ppm averaged over a 1-hour timeframe (``1-hour ozone
NAAQS'').\4\ In 1997, the EPA revised the primary and secondary ozone
NAAQS to set the acceptable level of ozone in the ambient air at 0.08
ppm averaged over an 8-hour timeframe (``1997 ozone NAAQS'').\5\
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\4\ 44 FR 8202 (Feb. 8, 1979).
\5\ 62 FR 38856 (July 18, 1997).
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The EPA further tightened the 8-hour ozone NAAQS to 0.075 ppm in
2008 (``2008 ozone NAAQS''),\6\ and to 0.070 ppm in 2015 (``2015 ozone
NAAQS''), however, this determination pertains to the 1997 ozone
NAAQS.\7\ The EPA subsequently revoked the 1-hour ozone NAAQS \8\ and
the 1997 ozone NAAQS,\9\ but has retained applicable requirements for
anti-backsliding purposes for areas that remained designated as
nonattainment for those standards at the time of revocation.\10\
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\6\ 73 FR 16436 (Mar. 27, 2008).
\7\ 80 FR 65292 (Oct. 26, 2015).
\8\ 70 FR 44470 (Aug. 3, 2005).
\9\ 80 FR 12264 (Mar. 6, 2015).
\10\ 40 CFR 51.1100(o).
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B. Sacramento Ozone Designations, Classifications, and SIP Revisions
The Sacramento Metro area consists of Sacramento and Yolo counties
and portions of El Dorado, Placer, Solano, and Sutter counties, and is
under the jurisdiction of the California Air Resources Board (CARB) and
the following regional air pollution control districts: the El Dorado
County Air Quality Management District (EDCAQMD), the Feather River Air
Quality Management District (FRAQMD), the Placer County Air Pollution
Control District (PCAPCD), the Sacramento Metropolitan Air Quality
Management District (SMAQMD), and the Yolo-Solano Air Quality
Management District (YSAQMD) (collectively, ``Districts'').\11\ The
area also includes Tribal lands under the jurisdiction of the Shingle
Springs Band of Miwok Indians, Shingle Springs Rancheria (Verona
Track), California; the United Auburn Indian Community of the Auburn
Rancheria of California; and the Yocha Dehe Wintun Nation, California.
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\11\ For a precise description of the geographic boundaries of
the Sacramento Metro area for the 1997 ozone NAAQS, refer to 40 CFR
81.305. Specifically included portions are the eastern portion of
Solano County, the western portions of Placer and El Dorado counties
outside of the Lake Tahoe Basin, and the southern portion of Sutter
County.
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CARB is the State agency responsible for the adoption and
submission to the EPA of California state implementation plan (SIP)
submissions. Under California law, air districts in California are
generally responsible for the development of regional air quality plans
and related rules. For the Sacramento Metro area, the Districts develop
and adopt air quality management plans and rules to address CAA
requirements applicable to the region. The Districts then submit such
plans and rules to CARB for adoption and submission to the EPA as
proposed revisions to the California SIP. In general, Tribes are not
required to submit tribal implementation plans.\12\
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\12\ See 40 CFR 49.4(a) (specifying that Tribes are not subject
to implementation plan submittal deadlines).
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Following promulgation of a new or revised NAAQS, the EPA is
required by CAA section 107(d) to designate areas throughout the nation
as attaining or not attaining the NAAQS. The EPA designated the
Sacramento Metro area as nonattainment for the 1997 ozone NAAQS on
April 30, 2004, and classified the area as ``Serious,'' effective June
15, 2004.\13\ On May 5, 2010, the EPA reclassified the area from
Serious to ``Severe-15,'' effective June 4, 2010.\14\ The area's
applicable attainment date for the 1997 ozone NAAQS is June 15,
2019.\15\
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\13\ 69 FR 23858 (Apr. 30, 2004).
\14\ 75 FR 24409 (May 5, 2010).
\15\ 74 FR 43654 (Aug. 27, 2009).
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On January 29, 2015, the EPA approved the planning elements
required as a result of a reclassification to Severe-15, including the
reasonable further progress (RFP) demonstration, the attainment
demonstration, and transportation control measures.\16\ As a
consequence of the reclassification to Severe-15, California was also
required to submit nonattainment new source review (NSR) program
revisions \17\ and CAA section 185 fee rules.\18\ At the time of
reclassification from Serious to Severe-15, the EPA had approved NSR
program revisions for YSAQMD and EDCAQMD into the California SIP,\19\
and our reclassification notice established a deadline for California
to submit the SMAQMD, PCAPCD, and
[[Page 58048]]
FRAQMD NSR program revisions.\20\ CARB submitted, and the EPA
subsequently approved, revisions to the SMAQMD, PCAPCD, and FRAQMD NSR
programs.\21\ CARB submitted, and the EPA approved, the SMAQMD
submittal for the CAA section 185 fee rule requirement in 2024.\22\ In
the 2010 reclassification notice, the EPA deferred the deadline for
submittal of EDCAQMD, PCAPCD, FRAQMD, and YSAQMD section 185 fee
rules.\23\ However, FRAQMD submitted Rule 7.15 to meet the CAA section
185 fee rule requirement for the Severe-15 ozone classification on July
5, 2022, and the EPA approved Rule 7.15 into the SIP on December 31,
2024.\24\ EDCAQMD submitted Rule 611 on March 13, 2024, and the EPA has
not yet acted on this rule. PCAPCD and YSAQMD have not submitted
section 185 fee rules for the 1997 ozone NAAQS.
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\16\ 80 FR 4795 (Jan. 29, 2015). The submittals included:
Sacramento Regional Nonattainment Area 8-Hour Ozone Reasonable
Further Progress Plan 2002-2008, Feb. 2006; Sacramento Regional 8-
Hour Ozone Attainment Plan and Reasonable Further Progress Plan,
Mar. 26, 2009; Elements of CARB's State Strategy, adopted by CARB on
Sep. 27, 2007; Elements of the Status Report on the State Strategy
for California's 2007 State Implementation Plan and Proposed
Revision to the SIP Reflecting Implementation of the 2007 State
Strategy, Mar. 24, 2009; and Sacramento Regional 8-Hour Ozone
Attainment Plan and Reasonable Further Progress Plan, 2013 SIP
Revisions, Sep. 26, 2013.
\17\ Nonattainment NSR program revisions are needed to redefine
the major source threshold and offset ratios when an area is
reclassified. A reclassification from Serious to Severe-15 changes
the major source threshold from 50 tons per year (tpy) VOC to 25 tpy
VOC.
\18\ CAA section 185 requires each State with an ozone
nonattainment area classified as ``Severe'' or ``Extreme'' to
develop, as a SIP revision, a fee collection rule to be implemented
in the event that an area fails to attain the ozone standards by the
required attainment date.
\19\ EDCAPCD Rule 523.1 was submitted to the EPA on Mar. 9,
2022, and SIP approved on Sep. 14, 2023 (88 FR 63031) and YSAQMD
Rule 3.4 was submitted to the EPA on Mar. 26, 1997, and SIP approved
on July 7, 1997 (62 FR 36214).
\20\ 75 FR 24409 (May 5, 2010).
\21\ SMAQMD Rule 214 was SIP approved on Aug. 29, 2013 (78 FR
53270), PCAPCD Rule 502 was SIP approved on Jan. 6, 2026 (91 FR
337), and FRAQMD Rule 10.1 was SIP approved on Oct. 5, 2015 (80 FR
60047).
\22\ 89 FR 15962 (Mar. 6, 2024).
\23\ 75 FR 24415 (May 5, 2010).
\24\ 89 FR 107012 (Dec. 31, 2024).
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C. The EPA's Clean Data Policy
Under the EPA's longstanding Clean Data Policy,\25\ which is
reaffirmed for the 1997 ozone NAAQS at 40 CFR 51.918, when an area has
attained the relevant 8-hour ozone standards, the Agency may issue a
CDD after notice and comment rulemaking determining that a specific
area is attaining the relevant standards. A CDD is not linked to any
particular attainment deadline and is not necessarily equivalent to a
determination that an area has attained the standard by its applicable
attainment deadline.\26\
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\25\ 1995 Seitz Memo.
\26\ The Clean Data Policy does not use the term ``clean data
determination,'' but generally describes conditions for the EPA to
determine that an area has attained air quality standards based on
monitoring data. 1995 Seitz Memo.
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The effect of a CDD is to suspend the requirement for an area to
submit an attainment demonstration, a reasonably available control
measures (RACM) analysis, an RFP plan, contingency measures, and any
other planning requirements related to attainment for as long as the
area continues to attain the standard.\27\ With respect to the
attainment demonstration requirements of CAA section 182(c)(2)(A),
under the Clean Data Policy, if an area already has air quality
monitoring data demonstrating attainment of the standard, there is no
need for the area to make a further submittal containing additional
measures to achieve attainment, nor is there a need for the area to
perform future modeling to show how the area will achieve
attainment.\28\ Similarly, the EPA interprets the CAA as not requiring
the submittal of RFP and associated quantitative milestones for areas
that are already attaining the NAAQS. For areas that are attaining the
NAAQS, showing that the State will make RFP towards attainment has no
meaning. Similar reasoning applies to other SIP submittal requirements
that are linked with attainment demonstration and RFP requirements. The
EPA interprets the obligation to submit contingency measures as
suspended when the area has attained the standard because those
contingency measures are directed at ensuring RFP and attainment by the
applicable date. A CDD does not suspend the requirements for an
emissions inventory, for NSR, or for a section 185 fee program.\29\
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\27\ In the context of CDDs, the EPA distinguishes between
attainment planning requirements of the CAA, which relate to the
attainment demonstration for an area and related control measures
designed to bring an area into attainment for the given NAAQS as
expeditiously as practicable, and other types of requirements, such
as permitting requirements under the nonattainment new source review
program, emissions inventory requirement, and specific control
requirements independent of those strictly needed to ensure timely
attainment of the given NAAQS. 40 CFR 51.918.
\28\ Id.
\29\ 40 CFR 51.918 lists attainment related planning
requirements that are suspended upon determination of attainment.
NSR requirements, emissions inventory requirements, and fee program
requirements for Severe and Extreme nonattainment areas are not
included in the list of suspended requirements.
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III. The EPA's Analysis
A. Applicable Statutory and Regulatory Provisions
A CDD is typically based on three years of complete, quality-
assured, and certified air quality monitoring data gathered at
established State and local air monitoring stations (SLAMS) and entered
into the EPA's Air Quality System (AQS) database.\30\ Data from ambient
air monitors operated by State/local agencies in compliance with EPA
monitoring requirements must be submitted to the AQS database.
Monitoring agencies annually certify that these data are accurate to
the best of their knowledge. Accordingly, the EPA relies primarily on
data in its AQS database when determining compliance with the
NAAQS.\31\ With respect to the 1997 ozone NAAQS, the EPA reviews data
to determine the area's air quality status in accordance with 40 CFR
part 50, appendix I.
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\30\ The AQS contains ambient air pollution data collected by
the EPA, State, local, and Tribal air pollution control agencies.
The AQS also contains meteorological data, descriptive information
about each monitoring station (including its geographic location and
its operator) and data quality assurance/quality control
information. The AQS data is used to (1) assess air quality, (2)
assist in attainment/non-attainment designations, (3) evaluate SIPs
for nonattainment areas, (4) perform modeling for permit review
analysis, and (5) prepare reports for Congress as mandated by the
CAA. The AQS is available at <a href="https://www.epa.gov/aqs">https://www.epa.gov/aqs</a>.
\31\ See 40 CFR 50.10; 40 CFR part 50, appendix I; 40 CFR part
53; 40 CFR part 58, and 40 CFR part 58, appendices A, C, D, and E.
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Under EPA regulations at 40 CFR 50.10, an area attains the 1997
ozone NAAQS 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 at each eligible monitoring site within the area. This 3-year
average is referred to as the ``design value.'' When the design value
is greater than 0.08 ppm at any monitor within the area, then the area
is violating the NAAQS.\32\ The data completeness requirement is met
when the average percent of days with valid ambient monitoring data is
greater than or equal to 90 percent and no single year has less than 75
percent data completeness, as determined under appendix I of 40 CFR
part 50.\33\
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\32\ The data handling convention in 40 CFR part 50, appendix I
dictates that 8-hour average concentrations shall be reported in ppm
to the third decimal place, with additional digits to the right
being truncated. The third decimal place of the computed value is
rounded, with values equal to or greater than 5 rounding up. Thus, a
computed 3-year average ozone concentration of 0.085 ppm is the
smallest value that is greater than 0.08 ppm.
\33\ 40 CFR part 50, appendix I, section 2.3(b).
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B. Clean Data Determination
The EPA is proposing to determine that the Sacramento Metro area
attained the 1997 ozone NAAQS and to issue a CDD for the area. Our
proposed determination is based on three years of quality-assured and
certified ambient air quality monitoring data collected in accordance
with 40 CFR part 58 and recorded in the EPA's AQS database for the
2023-2025 monitoring period. Preliminary data available in EPA's AQS
database for 2026 (January-March) indicate that the area continues to
show concentrations consistent with attainment of the 1997 ozone
NAAQS.\34\ The average of the annual fourth-highest daily maximum 8-
hour average ozone concentrations at each eligible monitoring site
within the area was below 0.08 ppm in these three years. As discussed
in Section II.D of this document, ambient air quality
[[Page 58049]]
monitoring data for the most recent 3-year period (i.e., 2023-2025) for
the 1997 ozone NAAQS for the Sacramento Metro area meet the data
completeness requirements in 40 CFR part 50, appendix I.
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\34\ Preliminary data for the first quarter of 2026 are posted
in AQS and are provided in the docket for this action. Preliminary
Design Value Report, AMP480, Report Request ID: 2403122, Aug. 19,
2026.
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C. Monitoring Network Considerations
CAA section 110(a)(2)(B)(i) requires States to establish and
operate air monitoring networks to compile data on ambient air quality
for all criteria pollutants. The ambient air monitoring network in the
Sacramento Metro area includes air monitoring stations that are managed
and operated by CARB, PCAPCD, SMAQMD, and YSAQMD. Although both EDCAQMD
and FRAQMD have jurisdiction in portions of the Sacramento Metro area,
neither district operates SLAMS ozone monitors in the area. CARB
operates SLAMS ozone monitors within the portion of the area under
EDCAQMD jurisdiction, and there are no ozone monitors within the
portion of the area under FRAQMD jurisdiction.\35\ CARB and SMAQMD
submit annual network plans to the EPA,\36\ which document the status
of CARB and the Districts' air monitoring networks, as required under
40 CFR 58.10. The EPA reviews these annual network plans for compliance
with the specific requirements in 40 CFR part 58. With respect to
ozone, we have found that the annual network plans submitted by CARB
and SMAQMD meet the minimum monitoring requirements of 40 CFR part
58.\37\
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\35\ The FRAQMD maintains jurisdiction in both Sutter County and
Yuba County. A portion of Sutter County is included in the
Sacramento Metro area, and none of Yuba County is included in the
area.
\36\ CARB's annual network plan includes the PCAPCD and YSAQMD
ambient air monitoring networks. SMAQMD submits its own annual
network plan.
\37\ We have included copies of CARB's and SMAQMD's annual
network plans for 2023-2025 in the docket for this action, along
with our reviews of these plans and our associated transmittal
correspondence.
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Finally, the EPA conducts regular technical systems audits (TSAs)
to review and inspect State and local ambient air monitoring programs
to assess compliance with applicable regulations concerning the
collection, analysis, validation, and reporting of ambient air quality
data. CARB is the primary quality assurance organization in California
that is responsible for overseeing the quality of data collected by
local air monitoring organizations, which includes the Districts. For
the purposes of this determination, we reviewed the findings from the
EPA's 2022 TSA of CARB's ambient air monitoring program.\38\ The
results of the TSA do not preclude the EPA from determining that the
Sacramento Metro area has attained the 1997 ozone NAAQS.
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\38\ See letter dated Mar. 14, 2024, from Matthew Lakin,
Director, Air and Radiation Division, EPA Region IX, to Edie Chang,
Deputy Executive Officer, CARB, and enclosure titled ``Technical
Systems Audit of the Ambient Air Monitoring Program: CARB, Dec.
2021-Aug. 2022.''
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D. Data Considerations
In accordance with 40 CFR 58.15, SMAQMD and CARB certify annually
that the previous year's ambient concentration and quality assurance
data are completely submitted to AQS and that the ambient concentration
data are accurate, taking into consideration the quality assurance
findings.\39\ SMAQMD certifies data from its monitoring network, and
CARB certifies data for the CARB network as well as the PCAPCD and
YSAQMD networks. There were 16 ozone monitoring sites located
throughout the Sacramento Metro area in calendar years 2023 through
2025: three within El Dorado County, four within Placer County, six
within Sacramento County, one within Solano County, and two within Yolo
County.\40\ Table 1 of this document summarizes the ozone monitoring
data from the various monitoring sites in the Sacramento Metro area by
showing the annual fourth-highest daily maximum concentrations and
design values over the 2023-2025 period. The data summarized in Table 1
of this document are considered complete for the purposes of
determining if the standard is met.\41\ The ozone data show that the
design values at the Sacramento Metro area monitoring sites were below
the 1997 ozone NAAQS of 0.08 ppm.
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\39\ We have included SMAQMD's and CARB's annual data
certifications for 2023, 2024, and 2025 in the docket for this
action.
\40\ See p. 9 of SMAQMD's 2025 Annual Network Plan (May 28,
2025) for a map illustrating the locations of the air monitoring
sites in the SMAQMD.
\41\ The criteria for data completeness are met at most of the
ozone monitors over the 2023-2025 period but were not met for the
ozone monitors at the Echo Summit, North Highlands--Blackfoot Way,
Elk Grove--Bruceville, and Sloughhouse monitoring sites.
Table 1--Sacramento Metro Area Fourth High 8-Hour Ozone Average Concentrations and Design Values (ppm) for 2023-
2025
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4th Highest daily maximum
AQS site ID Site name --------------------------------- Design value
2023 2024 2025 (2023-2025)
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EL DORADO COUNTY
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06-017-0012.......................... Echo Summit............. 0.065 Inc Inc Invalid.\a\
06-017-0011.......................... South Lake Tahoe--Sandy Inc Inc Inc Invalid.\b\
Way.
06-017-0020.......................... Cool.................... 0.072 0.072 0.065 0.069.
06-017-2004.......................... Placerville--Canal 0.067 0.067 0.063 0.065.
Street.
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PLACER COUNTY
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06-061-0003.......................... Auburn--Atwood.......... 0.064 0.079 0.067 0.070.
06-061-0004.......................... Colfax--City Hall....... 0.067 0.067 0.063 0.065.
06-061-0006.......................... Roseville--N Sunrise Ave 0.077 0.077 0.067 0.073.
06-061-2003.......................... Lincoln--2885 Moore Road 0.060 0.063 0.054 0.059.
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SACRAMENTO COUNTY
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06-067-0002.......................... North Highlands-- Inc Inc Inc Invalid.\c\
Blackfoot Way.
06-067-0006.......................... Sacramento--Del Paso 0.077 0.080 0.070 0.075.\d\
Manor.
06-067-0010.......................... Sacramento--T Street.... 0.066 0.069 0.065 0.066
06-067-0011.......................... Elk Grove--Bruceville... 0.050 0.048 0.059 Invalid.\e\
06-067-0012.......................... Folsom.................. 0.071 0.065 0.068 0.068.\f\
[[Page 58050]]
06-067-5003.......................... Sloughhouse............. Inc Inc 0.069 Invalid.\g\
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SOLANO COUNTY
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06-095-3003.......................... Vacaville............... 0.061 0.058 0.054 0.057.
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YOLO COUNTY
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06-113-0004.......................... Davis--UCD Campus....... 0.065 0.063 0.056 0.061.
06-113-1003.......................... Woodland--Gibson Road... 0.062 0.064 0.062 0.062.
----------------------------------------------------------------------------------------------------------------
Inc = Incomplete data. The required annual 75 percent completeness criterion was not met, therefore the annual
4th highest daily maximum values are not provided.
\a\ EPA approved the closure of the ozone monitor at the Echo Summit site on April 15, 2025, therefore the site
did not meet the 3-year data completeness criterion for 2023-2025. Additionally, the Echo Summit site had
incomplete annual ozone data due to accessibility challenges during the winter months.
\b\ The South Lake Tahoe--Sandy Way ozone monitor did not begin operation until April 15, 2025; therefore this
site will not have a valid 3-year design value for 2025.
\c\ SMAQMD lost the lease to the North Highlands--Blackfoot Way monitoring site and were forced to shut down the
ozone monitor on August 1, 2022. SMAQMD is looking to secure a new location for the site.
\d\ Per 40 CFR part 50, appendix I, section 2.3(b) SMAQMD submitted a request to the Regional Administrator to
count 32 missing days between January 11, 2022, and December 31, 2024, and 44 missing days between January 1,
2025, and October 2, 2025, towards the minimum data completeness requirements. This request was approved and
results in data completeness of at least 90 percent on average over the three-year period of 2023-2025 for the
site; therefore, this design value is considered valid. For more information regarding the Sacramento--Del
Paso monitor data certification and the State's request, see the SMQMD ozone data substitution analysis, EPA
approval letter, and data certification letters included in the docket for this action.
\e\ The required 3-year average completeness criterion was not met due to instrument downtime, therefore the
2023-2025 design value is invalid.
\f\ Per 40 CFR part 50, appendix I, section 2.3(b) SMAQMD submitted a request to the Regional Administrator to
count 22 missing days between October 16, 2023, and December 19, 2024, towards the minimum data completeness
requirements. This request was approved and results in data completeness of at least 90 percent on average
over the three-year period of 2023-2025 for the site; therefore, this design value is considered valid. For
more information regarding the Folsom monitor data certification and the State's request, see the SMAQMD ozone
data substitution analysis, EPA approval letter, and data certification letters included in the docket for
this action.
\g\ The Sloughhouse design value is invalid due to null coded data in AQS with poor quality assurance results
from July 2023 through April 2024.
Source: EPA, AQS Design Value (AMP480), Report Request ID: 2390187, June 18, 2026.
Consistent with the requirements in 40 CFR part 50, the EPA has
reviewed the quality-assured and certified ozone ambient air monitoring
data for completeness. The EPA reviewed the data as recorded in AQS for
the applicable monitoring period, collected at the monitoring sites in
the Sacramento Metro area, and has determined that the data are
generally complete, with the exceptions of the Echo Summit, North
Highlands--Blackfoot Way, Elk Grove--Bruceville, and Sloughhouse
monitoring sites. These exceptions are described here:
<bullet> The Echo Summit monitoring site typically operates
seasonally from April through October, but it could not operate during
the month of April in 2019 to 2024 because persistent weather
conditions made the access roads to the sites impassible.\42\ Due to
safety and accessibility issues, CARB submitted a site closure request
for the Echo Summit ozone monitor on February 10, 2025 as well as a
separate request to open a new ozone monitor at the South Lake Tahoe--
Sandy Way monitoring site with a proposed start date of April 1,
2025.\43\ The EPA approved CARB's closure request for the Echo Summit
monitoring site on April 15, 2025 and new monitor request for the South
Lake Tahoe--Sandy Way monitoring site on April 14, 2025.\44\ The South
Lake Tahoe--Sandy Way ozone monitor began operation on April 1, 2025.
Due to the accessibility challenges and site location change, Echo
Summit did not meet the 3-year completeness criterion of 90 percent for
the 2025 design value period. While Echo Summit did not have a valid
design value for the previous five years, for the five most recent
valid design value years (2010-2014), Echo Summit was not among the top
50 percent of design values for the Sacramento Metro area, was 0.016-
0.031 ppm lower than the highest design value site, and was below the
1997 ozone NAAQS.\45\
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\42\ See 2024 CARB Annual Network Plan, Appendix B. While the
2024 Annual Network plan only mentions 2019 through 2023, the same
weather conditions affected the 2024 data.
\43\ See letters dated Feb. 10, 2025, from Michael Miguel, CARB,
to Dena Vallano, EPA Region IX (conveying requests for Echo Summit
Ozone monitor closure and South Lake Tahoe--Sandy Way ozone monitor
start-up).
\44\ See letters dated Apr. 14, 2025, and Apr. 15, 2025, from
Dena Vallano, EPA Region IX, to Michael Miguel, CARB.
\45\ EPA AQS Design Value Report, AMP480, accessed June 18, 2026
(User ID: SHONG, Report Request ID: 2390187).
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<bullet> The North Highlands--Blackfoot Way monitoring site was
shut down on August 1, 2022, due to sudden loss of the lease providing
access to the monitor following the property's sale to another owner.
SMAQMD notified the EPA of this abrupt closure via letter on July 28,
2022,\46\ and documentation within the 2023 annual network plan.\47\
The North Highlands--Blackfoot Way monitoring site had design values
that were 0.006-0.012 ppm lower than the highest design value site for
the five previous valid design value years of its operation (2016-
2020), did not have the highest fourth-highest daily maximum 8-hour
ozone concentration in the Sacramento Metro area in the last five
[[Page 58051]]
years of operations (2018-2022), and were below the 1997 ozone
NAAQS.\48\
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\46\ See letter dated July 28, 2022, from Janice Lam Snyder,
Program Manager, SMAQMD, to Gwen Yoshimura, Air Quality Analysis
Office, EPA Region IX.
\47\ See 2023 SMAQMD Annual Network Plan, Appendix E.
\48\ EPA AQS Design Value Report, AMP480, accessed June 18, 2026
(User ID: SHONG, Report Request ID: 2193813).
---------------------------------------------------------------------------
<bullet> The Elk Grove--Bruceville site had several hours of
nullified data throughout 2023-2025 that resulted in a 3-year
completeness of 88 percent which did not meet the 90 percent 3-year
completeness criterion. While Elk Grove--Bruceville did not have a
valid 2025 design value, for the previous five valid design values
(2020-2024), Elk Grove--Bruceville was not among the top 50 percent of
design values for the Sacramento Metro area, was 0.012-0.021 ppm lower
than the highest design value site in the nonattainment area, and was
below the 1997 ozone NAAQS.\49\
---------------------------------------------------------------------------
\49\ Id.
---------------------------------------------------------------------------
<bullet> The Sloughhouse monitoring site failed an annual
performance evaluation due to an incorrectly installed ozone
calibrator, which resulted in data invalidation from July 2023 through
April 2024.\50\ As a result, the site did not meet the 3-year
completeness criterion of 90 percent and the 2023 and 2024 calendar
years did not meet the annual completeness criterion of 75 percent.
While Sloughhouse did not have valid design values for the most recent
three design value years (2023-2025), the Sloughhouse monitoring site
was 0.008-0.014 ppm lower than the highest design value site, below the
1997 ozone NAAQS, and did not have the highest fourth-highest daily
maximum 8-hour ozone concentration in the Sacramento Metro area for the
five previous valid design value years (2018-2022).\51\ Additionally,
the fourth-highest daily maximum 8-hour ozone concentration measured in
2025 was valid at 0.069 ppm, which is well below the 1997 ozone NAAQS.
---------------------------------------------------------------------------
\50\ See Data Certification Letter dated Jan. 15, 2025, from
Mark Loutzenhiser, SMAQMD, to Martha Guzman, EPA.
\51\ EPA AQS Design Value Report, AMP480, accessed June 18, 2026
(User ID: SHONG, Report Request ID: 2390187).
---------------------------------------------------------------------------
Historically, the design values for the Echo Summit, North
Highlands--Blackfoot Way, Elk Grove--Bruceville, and Sloughhouse
monitoring sites have consistently measured 0.005-0.015 ppm lower than
the highest design value site for the Sacramento Metro area.\52\
Therefore, we find that the invalid design values at the Echo Summit,
North Highland--Blackfoot Way, Elk Grove--Bruceville, and Sloughhouse
monitoring sites do not preclude an attainment determination for the
Sacramento Metro area. The remaining ozone monitoring sites meet the
data completeness requirements of 40 CFR part 50, appendix I.\53\
---------------------------------------------------------------------------
\52\ Id.
\53\ Id.
---------------------------------------------------------------------------
Per 40 CFR part 50, appendix I, section 2.3(b), ``[w]hen computing
whether the minimum data completeness requirements have been met,
meteorological or ambient data may be sufficient to demonstrate that
meteorological conditions on missing days were not conducive to
concentrations above the level of the standard. Missing days assumed
less than the level of the standard are counted for the purpose of
meeting the data completeness requirement, subject to the approval of
the appropriate Regional Administrator.'' Both the Sacramento--Del Paso
Manor and Folsom monitoring sites did not meet the data completeness
criterion of at least 90 percent on average over the three-year period
for the 2025 design value. However, SMAQMD submitted requests for the
EPA Region 9 Regional Administrator to approve inclusion of missing
days at the Sacramento--Del Paso Manor and Folsom monitors towards the
minimum data completeness requirements.\54\ These requests were
approved by the EPA and resulted in data completeness at or above 90
percent on average over the three-year period of 2023-2025 for the
Sacramento--Del Paso Manor and Folsom sites; therefore, these 2025
design values are considered valid.\55\
---------------------------------------------------------------------------
\54\ See SMAQMD 2022-2024 Ozone Data Substitution Analysis--Del
Paso Manor and Folsom Monitoring Sites and SMAQMD 2025 Ozone Data
Substitution Analysis--Del Paso Manor. For the Sacramento--Del Paso
Manor monitor, SMAQMD requested that the EPA include 32 missing days
between Jan. 11, 2022, and Dec. 31, 2024, and 44 missing days
between Jan. 1, 2025, and Oct. 2, 2025; for the Folsom monitor, the
District requested that the EPA include 22 missing days between Oct.
16, 2023, and Dec. 19, 2024.
\55\ See letter dated Apr. 30, 2026, from Michael Martucci, EPA
Region IX, to Mark Loutzenhiser, SMAQMD, and letter dated June 16,
2026 from Michael Martucci, EPA Region IX, to Mark Loutzenhiser,
SMAQMD.
---------------------------------------------------------------------------
Preliminary, not yet certified data available in the EPA AQS
database for 2026,\56\ indicate that the area continues to attain the
1997 ozone NAAQS. Prior to finalizing this action, we will examine all
preliminary and certified ozone monitoring data available to ensure
this trend persists. The AQS data reports for the Sacramento Metro area
for the three years 2023 through 2025 are included in the docket for
this rulemaking. Taking into account the extent and reliability of the
applicable ozone monitoring network, and the data collected therefrom
and summarized in Table 1 of this document, we are proposing to
determine that the Sacramento Metro area attained the 1997 ozone NAAQS
(as defined in 40 CFR part 50, appendix I) and on this basis to issue a
CDD for the area.
---------------------------------------------------------------------------
\56\ Preliminary data for the first quarter of 2026 are posted
in AQS and are provided in the docket for this action. Preliminary
Design Value Report, AMP480, Report Request ID: 2403122, Aug. 19,
2026.
---------------------------------------------------------------------------
E. Effects of This Proposed Determination
As discussed in Section II.C of this document, a CDD has the effect
of suspending certain planning requirements, including an attainment
demonstration, a reasonably available control measures (RACM) analysis,
an RFP plan, contingency measures, and any other planning requirements
related to attainment. The EPA approved these planning elements for the
Sacramento Metro area \57\ for the 1997 ozone standards on January 29,
2015, as discussed in Section II.B of this document.
---------------------------------------------------------------------------
\57\ 80 FR 4795 (Jan. 29, 2015).
---------------------------------------------------------------------------
A CDD does not suspend the CAA requirements to submit an emissions
inventory, revisions to nonattainment NSR programs, or rules for
section 185 fee programs. Of these three remaining requirements, the
Sacramento Metro area has fulfilled the emissions inventory requirement
and nonattainment NSR program revisions requirement, as discussed in
Section II.B of this document. Section II.B also notes that SMAQMD and
FRAQMD have met the CAA section 185 fee rule requirement. We will work
with the remaining districts to ensure the CAA section 185 fee rule
requirement is met throughout the area.
A CDD does not have the effect of redesignating an area to
attainment. Redesignation of an area to attainment requires that an
area has met all applicable requirements of CAA section 110 and part D,
and that the area has submitted, and the EPA has approved, a
redesignation request and maintenance plan.\58\ Therefore, if we
finalize this determination as proposed, the Sacramento Metro area will
remain subject to the requirements for an area that has been designated
nonattainment for the 1997 ozone NAAQS with a classification of Severe-
15. This proposed CDD, if finalized, will apply throughout the
nonattainment area, including to lands under the jurisdiction of CARB
and the Districts, and to lands under Tribal jurisdiction.
---------------------------------------------------------------------------
\58\ Memorandum dated Sep. 4, 1992, from John Calcagni,
Director, EPA Air Quality Management Division, to Regional Air
Directors, titled ``Procedures for Processing Requests to
Redesignate Areas to Attainment.''
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[[Page 58052]]
IV. The EPA's Proposed Action
The EPA is proposing to determine, based on the most recent three
years (2023-2025) of complete or otherwise validated, quality-assured,
and certified data meeting the requirements of 40 CFR part 50, appendix
I, that the Sacramento Metro area has attained the 1997 ozone NAAQS.
In conjunction with and based on our proposed determination that
the Sacramento Metro area has attained and is currently attaining the
1997 ozone NAAQS, in accordance with 40 CFR 51.918, the EPA is
proposing to issue a CDD for the Sacramento Metro area for the 1997
ozone NAAQS.
The Sacramento Metro area will remain subject to the requirements
for an area that has been designated nonattainment for the 1997 ozone
NAAQS until such time as the EPA determines, consistent with CAA
sections 107 and 175A, that the Sacramento Metro area meets the CAA
requirements for redesignation to attainment, including an approved
maintenance plan showing that the area will continue to attain the
standard for 10 years.
The EPA is soliciting public comments on the proposed action, our
rationale for the proposed action, and any issues discussed in this
document. We will accept comments from the public on this proposal for
the next 30 days and will consider comments before taking final action.
V. Statutory and Executive Order Reviews
Additional information about these statutes and Executive Orders
can be found at <a href="https://www.epa.gov/laws-regulations/laws-and-executive-orders">https://www.epa.gov/laws-regulations/laws-and-executive-orders</a>.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review. This action proposes to issue a CDD for the Sacramento
Metro area and imposes no new requirements.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
Executive Order 14192 does not apply because actions that make
attainment determinations under Clean Air Act section 181(b)(2) are
exempted from review under Executive Order 12866.
C. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA because this action does not impose additional requirements
beyond those imposed by State law.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities beyond those
imposed by State law. The proposed CDD does not create any new
requirements and does not directly regulate any entities.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. This action does not impose additional requirements
beyond those imposed by State law. Accordingly, no additional costs to
State, local, or tribal governments, or to the private sector, will
result from this action.
F. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government. Pursuant
to the CAA, this action proposes a CDD.
G. Executive Order 13175: Coordination With Indian Tribal Governments
Executive Order 13175 (65 FR 67249, Nov. 9, 2000), requires EPA to
develop an accountable process to ensure ``meaningful and timely input
by Tribal officials in the development of regulatory policies that have
Tribal implications.'' This action does not have Tribal implications,
as specified in Executive Order 13175, because this determination will
not impose substantial direct costs on Tribal governments or preempt
Tribal law. The EPA has identified Tribal areas within the Sacramento
Metro area. We note that this determination, if finalized, would apply
throughout the area, including on Tribal lands.
The EPA plans to notify the Tribes located within the boundaries of
the Sacramento Metro area of this proposed determination. Because a
final determination of attainment would not change the Tribe's existing
nonattainment designation or classification, the EPA does not plan to
offer government-to-government consultation on this proposed
determination, however, it is our practice to initiate government-to-
government consultation at the request of any Tribe.
H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the Agency has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. Therefore, this action is not
subject to Executive Order 13045 because it merely proposes a CDD meets
Federal requirements. Furthermore, the EPA's Policy on Children's
Health does not apply to this action.
I. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
J. National Technology Transfer and Advancement Act (NTTAA)
Section 12(d) of the NTTAA directs the EPA to use voluntary
consensus standards in its regulatory activities unless to do so would
be inconsistent with applicable law or otherwise impractical. The EPA
believes that this action is not subject to the requirements of section
12(d) of the NTTAA because application of those requirements would be
inconsistent with the CAA.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen oxides, Reporting and
recordkeeping requirements, Volatile organic compounds.
Dated: September 3, 2026.
Michael Martucci,
Acting Regional Administrator, Region IX.
[FR Doc. 2026-18755 Filed 9-11-26; 8:45 am]
BILLING CODE 6560-50-P
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.