[Federal Register Volume 85, Number 182 (Friday, September 18, 2020)]
[Rules and Regulations]
[Pages 58286-58294]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-18427]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2019-0654; FRL-10014-02-Region 9]


PM10 Maintenance Plan and Redesignation Request; 
Imperial Valley Planning Area; California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is taking final 
action to approve the ``Imperial County 2018 Redesignation Request and 
Maintenance Plan for Particulate Matter Less Than 10 Microns in 
Diameter (PM10) '' (``Imperial PM10 Plan'') as a 
revision to the California state implementation plan (SIP). The 
Imperial PM10 Plan includes, among other elements, a 
demonstration of implementation of best available control measures and 
a maintenance plan that includes an emissions inventory consistent with 
attainment, a maintenance demonstration, contingency provisions, and 
motor vehicle emissions budgets for use in transportation conformity 
determinations. In connection with the approval of the Imperial 
PM10 Plan, the EPA is determining that PM10 
precursors do not contribute significantly to elevated PM10 
levels in the area. The EPA is also approving the State of California's 
request to redesignate the Imperial Valley Planning Area from 
nonattainment to attainment for the PM10 national ambient 
air quality standards. The EPA is taking these actions because the SIP 
revision meets the applicable statutory and regulatory requirements for 
such plans and motor vehicle emissions budgets and because the area 
meets the Clean Air Act requirements for redesignation of nonattainment 
areas to attainment.

DATES: This rule is effective on October 19, 2020.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-R09-OAR-2019-0654. All documents in the docket are 
listed on the http://www.regulations.gov website. Although listed in 
the index, some information may not be publicly available, e.g., 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Certain other material, such as 
copyrighted material, is not placed on the internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available through http://www.regulations.gov. Please 
contact the person identified in the FOR FURTHER INFORMATION CONTACT 
section for additional availability information. If you need assistance 
in a language other than English or if you are a person with 
disabilities who needs a reasonable

[[Page 58287]]

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. By phone at 415-972-3964, or by 
email at [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, the terms ``we,'' 
``us,'' and ``our'' mean the EPA.

Table of Contents

I. Summary of Proposed Rule
II. Public Comments and EPA Responses
III. Final Action
IV. Statutory and Executive Order Reviews

I. Summary of Proposed Rule

    On April 2, 2020 (85 FR 18509), under section 110(k) of the Clean 
Air Act (CAA or ``Act''), the EPA proposed to approve the Imperial 
PM10 Plan submitted by the California Air Resources Board 
(CARB) by letter dated February 6, 2019, as a revision to the 
California SIP.\1\ In addition, under CAA section 107(d)(3)(D), we 
proposed to approve CARB's request to redesignate the Imperial Valley 
Planning Area to attainment for the PM10 national ambient 
air quality standards (NAAQS). We did so based on our conclusion that 
the area has met, or will meet as part of this action, all the criteria 
for redesignation under CAA section 107(d)(3)(E).
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    \1\ CARB submitted the Imperial PM10 Plan 
electronically on February 13, 2019, as an attachment to a letter 
dated February 6, 2019.
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    In our proposed rule, we provided background information on the 
NAAQS for particulate matter with an aerodynamic diameter less than or 
equal to a nominal ten micrometers (PM10); \2\ the area 
designations and related SIP revision requirements under the CAA; the 
Exceptional Events Rule (EER) codified at 40 CFR 50.1, 40 CFR 50.14 and 
40 CFR 51.930; and the PM10 planning for the Imperial Valley 
Planning Area.\3\ In short, in 1987, we established a NAAQS for 
PM10 of 150 micrograms per cubic meter ([micro]g/m\3\), 24-
hour average. Under the CAA Amendments of 1990 and based on monitoring 
data collected in the 1980s, a portion of Imperial County,\4\ referred 
to as the Imperial Valley Planning Area or Imperial Valley 
nonattainment area,\5\ was designated as a nonattainment area for the 
PM10 NAAQS. We classified the Imperial Valley Planning Area 
as a Moderate, and later, as a Serious nonattainment area for the 
PM10 NAAQS.\6\
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    \2\ Particulate matter is the generic term for a broad class of 
chemically and physically diverse substances that exist as discrete 
particles (liquid droplets or solids) over a wide range of sizes. 
Particles originate from a variety of anthropogenic stationary and 
mobile sources as well as from natural sources. Particles may be 
emitted directly or form in the atmosphere by transformations of 
gaseous emissions such as sulfur dioxide (SO2), oxides of 
nitrogen (NOX), volatile organic compounds (VOC), and 
ammonia (NH3). The chemical and physical properties of 
particulate matter vary greatly with time, region, meteorology, and 
source category. SO2, NOX, VOC, and 
NH3 are referred to as PM10 precursors. In 
this final rule, we are taking final action to find that precursors 
do not contribute significantly to elevated ambient PM10 
concentrations in the Imperial Valley Planning Area.
    \3\ 85 FR 18509, 18510-18512.
    \4\ Imperial County encompasses approximately 4,500 square miles 
in southeastern California. It is home to approximately 190,600 
people, and its principal industries are farming and retail trade. 
It is bordered by Riverside County to the north, Arizona to the 
east, Mexico to the south, and San Diego County and coastal 
mountains to the west. The Salton Sea straddles the boundary between 
Riverside and Imperial counties with most of the lake located in the 
northwest portion of Imperial County.
    \5\ The Imperial Valley Planning Area encompasses the western 
and central parts of the County and includes the Imperial Valley. 
The Imperial Valley runs north-south through the central part of the 
County. Most of the County's population and industries exist within 
this relatively narrow land area, which extends about one-fourth the 
width of the County.
    \6\ 69 FR 48972 (August 11, 2004).
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    In response to the nonattainment designation, CARB and the Imperial 
County Air Pollution Control District (ICAPCD or ``District'') adopted 
control measures, including the District's Regulation VIII (``Fugitive 
Dust Rules''), and air quality plans to attain the PM10 
NAAQS in the area. Regulation VIII has been strengthened through 
various amendments over the years since the area was designated 
nonattainment and is approved as part of the Imperial County portion of 
the California SIP. The District then developed the Imperial 
PM10 Plan in light of ambient PM10 data that 
showed that, with concurrences by the EPA on flagged exceptional events 
under the EER, the area had attained the standard.
    For our proposed rule, we reviewed CARB's request for redesignation 
for compliance with the criteria for redesignation in CAA section 
107(d)(3)(E) and determined that the Imperial Valley Planning Area met 
the criteria for redesignation from nonattainment to attainment for the 
PM10 NAAQS. First, in our proposed rule, based on complete, 
quality-assured and certified data for the 2014-2018 period, we found 
that the Imperial Valley Planning Area attained the PM10 
NAAQS in 2016 and has continued to attain since that time.\7\ Our 
proposed determination of attainment reflects concurrences by the EPA 
on a number of exceedances that had been flagged as exceptional events 
by CARB and the District.
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    \7\ 85 FR 18509, 18513-18515.
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    Second, in our proposed rule, we found that, with approval of 
certain SIP elements for which we proposed approval, the Imperial 
Valley Planning Area will have a fully approved applicable SIP under 
section 110(k) that meets all applicable requirements under section 110 
and part D for the purposes of redesignation.\8\ In connection with our 
determination that all applicable requirements under section 110 and 
part D were satisfied, we proposed to find, based on CARB's ambient 
PM2.5 mass and speciation analysis, that PM10 
precursors do not significantly contribute to elevated PM10 
concentrations in the Imperial Valley Planning Area and will not do so 
over the course of the initial 10-year maintenance plan. We also 
proposed to approve the best available control measures (BACM) 
demonstration included in the Imperial PM10 Plan as meeting 
the requirements of CAA section 189(b)(1)(B) based on our prior 
approval of the District's Regulation VIII fugitive dust rules and our 
conclusion that the Regulation VIII rules cover all significant 
PM10 source categories in the Imperial PM10 
nonattainment area.\9\
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    \8\ Id. at 18515-18519.
    \9\ Id. at 18517-18518.
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    Third, based on our previous approval of the District's Regulation 
VIII fugitive dust rules as part of the Imperial County portion of the 
California SIP, we proposed to find that the improvement in air quality 
in the Imperial Valley Planning Area is due to permanent and 
enforceable emissions reductions.\10\ Fourth, we proposed to approve 
the Imperial PM10 Plan as satisfying the requirements for 
maintenance plans under CAA section 175A.\11\ In so doing, we proposed 
to approve the plan's attainment year (2016) emissions inventory as 
meeting the emissions inventory requirements under CAA section 
172(c)(3), the plan's maintenance demonstration showing attainment 
through 2030, the District's commitments to verify continued 
attainment, and the contingency plan.
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    \10\ Id. at 18519-18520.
    \11\ Id. at 18520-18526.
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    Lastly, we proposed to approve the motor vehicle emissions budgets 
(MVEBs or ``budgets'') in the Imperial PM10 Plan for direct 
PM10 for 2016 and 2030 for transportation conformity 
purposes because they meet all applicable criteria for such budgets 
including the adequacy criteria under 40 CFR 93.118(e). The MVEBs are 
shown in table 1, below. In our

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proposed rule, we explained that the applicable source categories 
included in the budgets include vehicle emissions (including exhaust, 
brake wear, and tire wear) and entrained dust from vehicle travel over 
paved and unpaved roads. With respect to unpaved road dust, we 
explained that the budgets include only those emissions generated by 
vehicle travel over city- and county-owned unpaved roads, not canal 
roads, farm roads or those owned by the U.S. Bureau of Land Management 
or the U.S. Forest Service. In addition, we mistakenly noted that the 
budgets reflect vehicle miles traveled (VMT) throughout the entire 
County, including the portion of the County that lies outside of the 
PM10 nonattainment area; however, we now understand that the 
budgets reflect the VMT only within the Imperial Valley Planning Area, 
not the entire county.\12\
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    \12\ For this final rule, we have confirmed with CARB and the 
Southern California Association of Governments (SCAG) that the 
budgets are based on VMT estimates for the Imperial Valley Planning 
Area, not the entire County. See email correspondence from Nesamani 
Kalandiyur, Manager, Transportation Analysis Section, CARB, to 
Karina O'Connor, Air Planning Office, EPA Region IX, August 7, 2020.

  Table 1--Transportation Conformity Budgets for the PM10 NAAQS in the
 Imperial Valley Planning Area--PM10 Tons Per Day (tpd), Annual Average
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                 Source                        2016            2030
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Tire Wear, Brake Wear and Exhaust.......             0.4             0.5
Paved Road Dust.........................             1.2             1.5
Unpaved City-County Road Dust...........            18.4            16.8
Total...................................            20.0            18.8
Motor Vehicle Emission Budget \ a\......              20              19
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\a\ Rounded up to the nearest integer.
Source: Imperial PM10 Plan, Table 4-5.

    Please see our April 2, 2020 proposed rule for a detailed 
discussion of the background for this action and the rationale for our 
proposed approval of the Imperial PM10 Plan and for granting 
California's request for redesignation of the Imperial Valley Planning 
Area to attainment.

II. Public Comments and EPA Responses

    Our April 2, 2020 proposed rule provided a 30-day public comment 
period that closed on May 4, 2020. During this period, we received 
comments from a private citizen and from the Torres Martinez Desert 
Cahuilla Indian Tribe (``Torres Martinez Tribe'' or ``Tribe''). A 
summary of the comments and our responses follow.
    Comment 1: The private citizen commenter contends that air 
pollution and particulate matter in the Imperial Valley will continue 
to increase as the shoreline of the Salton Sea continues to recede due 
to reduced water inflows. The commenter asserts that increased exposure 
of the lakebed will allow toxic particulate matter from the lakebed to 
become airborne, resulting in adverse public health impacts and adverse 
effects on farmland and crops downwind of the Salton Sea. The commenter 
urges the EPA to include ambitious restoration requirements for the 
Salton Sea as part of this action.
    Response 1: The commenter correctly notes that the Salton Sea will 
continue to recede, exposing an increasing amount of the lakebed. The 
EPA agrees that this creates the potential for increases in airborne 
particulate matter from the lakebed that can potentially have adverse 
impacts on human health and the environment, including on crops.
    The Imperial PM10 Plan addresses the potential for 
increased emissions from the Salton Sea. The Plan includes a 
description of the efforts underway to evaluate and proactively control 
this emerging source in Chapter 5, ``Salton Sea Considerations,'' in 
Appendix I, ``Salton Sea Management Program Phase 1: 10-Year Plan 
(March 2017),'' and in Appendix J, ``Salton Sea Air Quality Mitigation 
Program (July 2016).'' \13\
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    \13\ The District summarizes the approach to controlling dust 
from the lakebed as follows:
    The Salton Sea will continue to shrink, especially as drainage 
flows from local agricultural use are significantly reduced in 2017 
and beyond. Stabilizing the parts of the playa expected to be 
emissive as they are exposed will minimize dust. The State's Salton 
Sea Management Program (SSMP) and Phase I Plan and [the Imperial 
Irrigation District's] Salton Sea Air Quality Management Program (SS 
AQM Program) are designed to proactively provide reasonable controls 
as the playa is exposed. 2016 Amendments to ICAPCD Rule 804 allow 
establishment of alternate BACM on exposed playa that is not 
stabilized; this provides an adopted contingency mechanism for any 
emissive playa that is not stabilized as it is exposed. Imperial 
PM10 Plan, 5-1.
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    As we noted in our proposed rule, these efforts include the State's 
establishment in 2015 of the Salton Sea Task Force, which has developed 
a 10-year plan that endeavors to expedite wildlife habitat construction 
and to suppress dust from playa that will be exposed in the future. The 
Imperial Irrigation District's Salton Sea Air Quality Mitigation 
Program, which applies in addition to other programs and requirements, 
represents another of these efforts. It includes three components: a 
monitoring program and development of an emissions inventory; a dust 
control strategy that includes the development and testing of dust 
control measures; and the implementation of an annual proactive dust 
control plan that includes performance modeling.
    The District also notes that state law and water transfer permits 
include requirements to control PM10 emissions from exposed 
lakebed, and that District Rule 804, which requires the control of 
fugitive dust from open areas, also applies to the playa. In our notice 
of proposed rulemaking, we explained that Rule 804 provides that all 
persons who own or otherwise have jurisdiction over an open area are 
required to choose from a list of best available control measures to 
achieve a stabilized surface and to limit visible dust emissions to 20 
percent opacity. All EPA-approved District rules, including Rule 804, 
are enforceable by the EPA and by citizens.\14\ Of note, in June 2020, 
the District issued notices of violations to the Imperial Irrigation 
District and the U.S Fish and Wildlife Service for alleged violations 
of dust controls required by District rules. While the specific 
restoration projects at the Salton Sea are not a part of the Imperial 
PM10 Plan, enforcement of District Regulation VIII fugitive 
dust rules, particularly Rule 804, provide a mechanism to ensure that 
such projects include and implement reasonable dust controls that will 
reduce airborne dust emissions, including any toxic

[[Page 58289]]

constituents in those emissions, and related downwind impacts.
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    \14\ See CAA sections 113 and 304.
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    Comment 2: The Torres Martinez Tribe does not support the proposed 
redesignation and is very concerned about existing elevated levels of 
PM10 in the region and the likely increase in 
PM10 emissions from the lowering of the Salton Sea. The 
Tribe finds the effort to redesignate Imperial County attainment for 
the PM10 NAAQS to be completely contrary to the Imperial 
County Board of Supervisors' unanimous vote to declare a Local State of 
Emergency at the Salton Sea. The Tribe further notes that local media 
has reported that Imperial County's Public Health Officer has expressed 
concerns about public health due to dust storms, citing the high and 
increasing asthma rates.
    Response 2: With respect to existing elevated levels of 
PM10, in our proposed rule, we reviewed the ambient 
PM10 data for years 2014 through 2018 collected by CARB and 
the District at the various monitoring sites in the Imperial Valley 
Planning Area and found that the area has attained the PM10 
NAAQS. The data from 2014 through 2018 included a number of exceedances 
of the PM10 NAAQS that were flagged by CARB and the District 
as exceptional events due to high winds. As noted in the proposed rule, 
we reviewed the exceptional events documentation provided by CARB and 
the District for compliance with the EER and concurred that 91 
exceedance days qualify for exclusion under the EER. Under the EER, 
exceedances flagged as exceptional events for which the EPA issues 
concurrences are excluded from determinations made in connection with 
area redesignations.\15\ Thus, while we acknowledge the occurrence of 
elevated PM10 concentrations in the Imperial Valley Planning 
Area, we have determined that, once exceptional events are excluded, as 
provided for under the EER, the area attained the PM10 NAAQS 
in 2016 and continued to attain the standard in 2017 and 2018. We have 
also reviewed the ambient PM10 data for 2019 and the first 
half of 2020 and find that they are consistent with continued 
attainment of the PM10 NAAQS in the Imperial Valley Planning 
Area.
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    \15\ 40 CFR 50.14(a)(1)(i)(A) and (b)(1).
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    With respect to the potential for increases in airborne 
PM10 that could result from the increased exposure of the 
lakebed around the Salton Sea, we share the Tribe's concern. As we 
describe in response to Comment 1, there are mechanisms in place and 
efforts underway to proactively address this emerging issue. Should 
these efforts fall short, the District, the EPA, and citizens are able 
to enforce the District's EPA-approved rules, including Rule 804, which 
requires that persons who own or otherwise have jurisdiction over an 
open area, including the exposed lakebed, achieve a stabilized surface 
and limit opacity to 20 percent.
    Lastly, we acknowledge the Imperial County Board of Supervisors' 
proclamation of a local emergency for air pollution at the Salton Sea 
but do not view the proclamation as irreconcilable with the 
redesignation request also adopted by the Imperial County Board of 
Supervisors (as members of the Imperial County Air Pollution Control 
Board of Directors).\16\ In our proposed rule, we noted that the 
proclamation was based primarily on ambient PM10 
concentration data collected at two nonregulatory monitors located 
immediately west of the Salton Sea at Salton City and Naval Test Base 
that showed exceedances of the PM10 NAAQS. Nonregulatory 
monitors are those that have not been determined to meet the applicable 
requirements in 40 CFR part 50, 53 and 58, which include detailed 
sampling, siting, and quality assurance requirements. The data from 
nonregulatory monitors are not considered in determining whether an 
area attained or failed to attain the NAAQS, but the data are 
appropriate for other purposes. In this case, under the Salton Sea Air 
Quality Mitigation Program, the nonregulatory data are used to produce 
the annual emissions inventories, assemble dust control plans, and 
evaluate the performances of the dust control plans.\17\
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    \16\ The proclamation was transmitted to the State via a letter 
dated November 4, 2019, from Tony Rouhotas, Jr., County Executive 
Officer, to Gavin Newsom, Governor of the State of California.
    \17\ Imperial PM10 Plan, 5-5.
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    The State of California's initial response to Imperial County's 
proclamation is contained in a letter dated January 6, 2020, from Wade 
Crowfoot, Secretary for Natural Resources and Jared Blumenfeld, 
Secretary for Environmental Protection (referred to herein collectively 
as the ``State''), which is included in the docket for this rulemaking. 
The letter from the State acknowledges the urgent public health problem 
posed by the Salton Sea and outlines the significant work underway \18\ 
to address the concerns voiced by the County supervisors. The letter 
also notes that ``a study funded by the National Institute of Health is 
currently underway to determine the health effects of childhood 
exposure to particulate matter and inform public health action in the 
Imperial Valley.'' \19\ Thus, rather than viewing the proclamation of 
local emergency as contrary to the redesignation request, we find the 
County's proclamation and the State's response to be further evidence 
that the emerging playa at the Salton Sea will be appropriately 
controlled to reduce dust impacts as anticipated in the maintenance 
demonstration of the Imperial PM10 Plan.\20\
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    \18\ Among other things, the State agencies cite progress on 
agreements that will allow for a 3,770 acre species conservation 
habitat project to move forward, the acceleration of dust 
suppression projects that will help ensure the exposed lakebed does 
not worsen air quality, and the development of a Dust Suppression 
Action Plan.
    \19\ More information about the study, ``The Salton Sea and 
Children's Health: Assessing Imperial Valley Respiratory Health and 
the Environment,'' is available at https://www.niehs.nih.gov/research/supported/translational/peph/prog/rta/cfg/usc/index.cfm.
    \20\ 85 FR 18509, at 18522-18523.
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    Finally, we note that, in support of the redesignation request, the 
Imperial PM10 Plan includes a maintenance plan and related 
contingency provisions to address future violations of the 
PM10 NAAQS that are recorded at any of the regulatory 
monitoring sites after redesignation of the area to attainment. In 
accordance with the contingency provisions in the Imperial 
PM10 Plan, if the EPA determines that contingency provisions 
have been triggered by a violation of the PM10 NAAQS in the 
Imperial Valley Planning Area, the District would have 18 months from 
the EPA notification date to evaluate the cause of the exceedance and 
to take the appropriate action.\21\ Such action could include 
strengthening the fugitive dust rules in District Regulation VIII as 
necessary to address windblown dust off the playa if such dust is found 
to be the cause of the violation. The contingency provisions in the 
Imperial PM10 Plan thereby provide support for the ongoing 
effort to address the dust issues associated with emerging playa around 
the Salton Sea.
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    \21\ The contingency plan is contained in Section 4.4 of the 
Imperial PM10 Plan. The contingency plan is considered to 
be an enforceable part of the SIP.
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    Comment 3: The Tribe asserts that the redesignation proposal will 
potentially allow or make it easier for new sources of PM10 
to begin emitting in the area.
    Response 3: The District is responsible for the regulation of 
stationary sources and its rules govern the issuance of air permits. 
While no PM10 controls in the SIP would be relaxed or 
suspended upon redesignation of the area to attainment, federal 
permitting requirements for new or modified major stationary sources 
would shift from the District's federal nonattainment new source review

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(NNSR) program to its prevention of significant deterioration (PSD) 
program.
    NNSR requires the application of the highest level of control 
(lowest achievable emissions rate or LAER) to sources that have the 
potential to emit 70 tons of PM10 per year and the 
offsetting of new emissions.\22\ PSD requires best available control 
technology and a demonstration that the source (or major modification) 
will not cause significant deterioration of air quality or interfere 
with attainment or maintenance of the NAAQS for sources that emit more 
than 100 tons per year for certain listed source categories, or 250 
tons per year for unlisted categories.\23\ Upon redesignation to 
attainment, new PM10 major sources and major modifications 
with significant PM10 emissions at major sources will be 
required to obtain a PSD permit or address PM10 emissions in 
their existing PSD permit. Sources with potential emissions below the 
major threshold are subject to the District's minor new source review 
program. Under federal minor NSR SIP requirements, compliance with SIP 
rules and a determination that the new or modified source will not 
interfere with attainment or maintenance of the NAAQS is required.\24\ 
Thus, although new or modified stationary sources emitting 
PM10 emissions greater than the applicable NNSR thresholds 
would no longer be subject to the LAER or offset requirements once the 
area is redesignated, the minor source and PSD programs would ensure 
that permits would include conditions intended to assure compliance 
with applicable District rules, such as Regulation VIII, and would only 
be issued if the applicant demonstrates that the new or modified source 
would not cause a violation of the NAAQS.
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    \22\ CAA sections 172(c)(3), 173, 189(a)(1)(A) and 189(b)(3). 
District Rule 207 (``New and Modified Stationary Source Review'') is 
the District's rule implementing federal NNSR requirements. We 
approved District Rule 207 as meeting the NNSR requirements for 
PM10 at 82 FR 41895 (September 5, 2017).
    \23\ 40 CFR 52.21(b)(1), (j) and (k) (July 1, 2012 CFR version). 
District Rule 904 (``Prevention of Significant Deterioration (PSD) 
Permit Program'') is the District's rule incorporating the PSD 
requirements in 40 CFR 52.21. We approved Rule 904 at 77 FR 73316 
(December 10, 2012).
    \24\ 40 CFR 51.160(a). The District's minor source program is 
also contained in District Rule 207. District Rule 207, section 
(D.1.c) requires authorities to construct for all new or modified 
stationary sources to include conditions necessary to assure 
compliance with District rules, such as the fugitive dust rules in 
Regulation VIII, and section (F.) sets forth the air quality impact 
analysis requirements for new or modified stationary sources, 
including a demonstration that a new or modified source would not 
cause or worsen a NAAQS violation.
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    Comment 4: The Tribe believes flawed or inadequate analyses were 
utilized in the proposed redesignation. First, the Tribe is concerned 
that CARB and Imperial County APCD certified their monitoring data as 
complete and accurate, despite some monitors being incorrectly 
configured or operated in such a way that they couldn't accurately 
measure concentrations of PM10 greater than 985 or 995 
[mu]g/m\3\, which are known to be present in the region. Consequently, 
the Tribe contends that the data are biased low. The Tribe notes that 
the dataset includes numerous hourly PM10 values of 985 or 
995 [mu]g/m\3\, which are the maximum concentrations that samplers were 
configured to record. According to the Tribe, the actual, accurate 
measurements are most likely higher than the concentration values 
submitted to the EPA and certified as accurate.
    The Tribe asserts that this inaccuracy (bias low) in the highest 
and most important measurements of the dataset affects the analysis in 
two ways. First, for days where the NAAQS was exceeded and monitors 
recorded values of 985 or 995 [mu]g/m\3\, accurate information about 
the spatial distribution of PM10 measurements across the 
region was not available for the exceptional events analysis, and this 
lack of accurate data to access the spatial distribution of 
PM10 across the region limits the exceptional events 
analysis and conclusions. Second, days that did not appear to have 
exceeded the NAAQS but had high winds and one or more hourly values of 
985 or 995 [mu]g/m\3\, likely would have exceeded if the actual 
concentrations had been accurately recorded. The Tribe believes that 
days such as these should have been included in the exceptional events 
analysis.
    The Tribe asserts that CARB and the District knowingly operated 
these monitors and reported low biased concentrations for the over-
range hours, although the sampler manufacturer provided a variety of 
options for obtaining the correctly calculated hourly values. These 
options included changing the sampler range to allow measurements in 
the range known to occur in the region as well as manually retrieving 
the over-range values from a file contained in the sampler's memory. 
The Tribe notes that, during this period, the Torres Martinez 
PM10 monitoring program (using the same type of monitor) was 
able to operate their PM10 sampler, following manufacture's 
guidance, to accurately measure values greater than 995 [mu]g/m\3\.
    Response 4: Attainment of the PM10 NAAQS is determined 
by measuring PM10 in ambient air using either a Federal 
Reference Method (FRM) or a Federal Equivalent Method (FEM) in 
accordance with 40 CFR part 53. During the data years associated with 
this action (2014-2018), both CARB and ICAPCD operated Met One Beta 
Attenuation Monitor (BAM) 1020 p.m.10 monitors, which are 
designated as FEM monitors (EQPM-0798-122), at monitoring sites in the 
Imperial PM10 nonattainment area. Data from these monitors 
form part of the data record used in this action. The method is further 
described in the EPA List of Designated Reference and Equivalent 
Methods.
    Historically, the maximum concentration that this monitor could 
measure was a function of two instrument settings: The offset, which 
sets the minimum concentration measured by the instrument, and the 
range, which sets the full-scale range of the concentration measurement 
system. The standard range setting for the BAM 1020 is 1,000 [micro]g/
m\3\ with a default offset of -15 [micro]g/m\3\. For this reason, the 
maximum full-scale concentration that can be measured using the 
standard range and default offset is 985 [micro]g/m\3\. There are also 
several optional range settings, up to 10,000 [micro]g/m\3\. The FEM 
designation does not list specifications for the selection of the range 
and offset values to be used by the instrument but states that the 
``[i]nstrument must be operated in accordance with the appropriate 
instrument manual.'' \25\
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    \25\ EPA, Center for Environmental Measurements & Modeling, Air 
Methods & Characterization Division (MD-D205-03), List of Designated 
Reference and Equivalent Methods, June 15, 2020.
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    The BAM 1020 instrument manual has been revised many times since 
its initial FEM designation, including several revisions during the 
2014 to 2018 time period. An early revision of the BAM 1020 instrument 
manual relevant to the earliest data used in this action (revision K, 
released in October 2012) and a more recent revision (revision U, 
released in November 2017) both include information concerning the 
standard and optional ranges.\26\ The 1,000 [micro]g/m\3\ setting is 
consistently described as the standard range setting. Both versions of 
the manual state that the range may be set higher; however, increasing 
the range setting reduces the

[[Page 58291]]

digital resolution at lower concentrations. The manuals caution against 
setting the range higher than the standard range unless necessary, due 
to this loss of resolution.
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    \26\ These manuals were selected as appropriate references for 
instrument operation based on their coverage and applicability to 
the 2014-2018 data record. The FEM designation does not require that 
agencies must use only the most recent version of the manual, and 
agencies typically require time to implement updated manual releases 
into their operational and quality assurance procedures.
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    After evaluation and consideration of these factors, including the 
potential loss of resolution at lower concentrations, CARB and ICAPCD 
chose to transition from the standard range to one of the other 
optional ranges. The CARB-operated Calexico (AQS ID: 06-025-0005) 
monitors' upper range was increased to 5,000 [micro]g/m\3\ on December 
5, 2017. The ICAPCD-operated Brawley (AQS ID: 06-025-0007), El Centro 
(AQS ID: 06-025-1003), Niland (AQS ID: 06-025-4004), and Westmorland 
(AQS ID: 06-025-4003) monitors' upper ranges were increased to measure 
concentrations to 10,000 ug/m\3\ on August 30, 2018, March 16, 2018, 
January 28, 2019, and December 27, 2018, respectively. While hourly 
data collected prior to these dates is subject to the limitations of 
the standard range setting, during that period the instrument was 
operated consistent with the method designation, the instrument manual, 
and relevant EPA regulations (40 CFR parts 50, 53, and 58); and the EPA 
therefore considers this data valid and appropriate for use in 
comparison to the NAAQS.
    The EPA disagrees with the Tribe's assertion that on days where the 
NAAQS was exceeded and at least one monitor reported an hourly 
concentration at the maximum value allowed by the range setting, the 
inaccuracy of this value limits the exceptional events conclusions and 
analysis. The EPA reviews the information and analyses in an air 
agency's exceptional events demonstration package using a weight of 
evidence approach. The EPA considers a variety of evidence when 
evaluating whether the exceptional event criteria were met, and weighs 
the available evidence based on its relevance, degree of certainty, 
persuasiveness, and other considerations appropriate to the individual 
pollutant, as well as the nature and type of event. As further 
described in the response to the following comment, the EPA considered 
many types of analyses in its consideration of the exceptional event 
demonstrations concurred on in this action, several of which are 
independent of the hourly data reported by the instrument. Concerns 
that the highest hourly concentrations reported by the instrument may 
have been artificially low for some events do not undermine the weight 
of evidence showing that there was a clear causal relationship between 
the monitored exceedances and the associated high wind dust events.
    The EPA also disagrees with the Tribe's assertion that days that 
did not exceed the NAAQS but at least one monitor reported an hourly 
concentration at the maximum value allowed by the range setting should 
have been reviewed as exceptional events. As described above, the EPA 
considers the reported data valid and appropriate for use in comparison 
to the NAAQS. The days referenced by the Tribe are therefore not 
eligible for treatment as exceptional events because they do not 
contribute to an exceedance or violation of any NAAQS.
    Finally, data collected after all instruments were re-ranged 
continue to be consistent with attainment of the NAAQS in the Imperial 
Valley Planning Area. Based on certified 2019 data available in the Air 
Quality System (AQS), only two exceedance days were recorded in 2019: 
May 16, 2019 at Brawley and May 21, 2019 at Brawley, Niland and 
Westmorland. Preliminary 2020 data available in AQS and AirNow Tech 
indicate that no PM10 exceedances were measured in the 
Imperial Valley Planning Area through June 30, 2020. While the lower 
number of exceedances may be the result of multiple factors, including 
changes in weather, more recent data continue to be consistent with the 
EPA's finalization of this action.
    Comment 5: The Tribe is concerned that some exceptional events 
analyses did not consider that the non-homogenous pattern of spatial 
impacts across the region could indicate that the exceedances were not 
due to transport from areas with sustained winds speeds of greater than 
25 miles per hour (mph), but instead were due to poorly controlled 
local emissions in areas that were not experiencing sustained wind 
speeds of greater than 25 mph and therefore would not qualify for 
exclusion. The Tribe notes that some of the exceptional events days 
excluded from the data set showed dramatic variations in measured 
PM10 between nearby sites. The exceptional events analysis 
made the case that the exceedance was due to transport of emissions 
from an outside area that experienced sustained winds greater than 25 
mph. According to the Tribe, one would expect transported emissions to 
affect nearby monitoring sites in a somewhat homogenous fashion, which 
did not occur in some cases, suggesting that these exceedances were 
primarily caused by poorly controlled local emissions where there were 
not sustained winds greater than 25 mph.
    Response 5: Exceptional events demonstrations for high wind dust 
events must show that there exists a clear causal relationship between 
the specific high wind dust event and the monitored exceedance at each 
monitor, i.e., the demonstrations must address this criteria for each 
individual monitor that measured an exceedance caused by the particular 
event. Contrary to the commenter's statement, spatial homogeneity of 
high PM10 concentrations is not always expected with a high 
wind dust event and a homogenous increase in PM10 
concentrations is not a necessary factor to demonstrate a clear causal 
relationship between a high wind dust event and observed exceedances. 
The EPA evaluated other analyses and evidence provided in the 
demonstrations and related addenda and concluded that the weight of the 
evidence established a clear causal relationship between each specific 
high wind dust event and each individual concurred exceedance. These 
analyses in the demonstrations typically included information such as: 
Historical PM10 monitoring data; time-series graphs and 
tables of PM10 concentrations, wind speeds, wind gusts, and 
wind directions; hourly PM10 concentrations; National 
Oceanic and Atmospheric Administration (NOAA) Hybrid Single Particle 
Lagrangian Integrated Trajectory Model (HYSPLIT) back trajectories 
showing potential source regions; upwind wind speed and directions; and 
National Weather Service (NWS) reports and advisories.
    The Tribe specifically expressed concern that spatial non-
homogenous exceedances were a result of local sources of emissions with 
wind speeds less than 25 mph rather than transport from areas with 
sustained winds greater than 25 mph. For these exceedances, the EPA 
believes that the clear casual analyses demonstrated that the 
exceedances were caused by high wind dust exceptional events. In 
instances where the high winds that generated dust emissions were 
measured outside of the Imperial Valley Planning Area, NOAA HYSPLIT 
trajectories included in the demonstrations were consistent with 
transport from those outside areas. This, along with other supporting 
documentation and analyses in the demonstration, indicates that a clear 
causal relationship existed between the specific high wind dust event 
and the monitored exceedances.
    Further, the EPA believes that the demonstrations addressed the 
potential influence of poorly controlled local

[[Page 58292]]

sources in showing that the events were not reasonably controllable. 
High wind dust demonstrations must address this criterion by showing 
that reasonable measures to control the influence of event-related 
emissions on air quality were implemented at the time of the event. 
This includes an assessment of relevant natural and anthropogenic 
sources that may be causing or contributing to the monitored 
exceedances, including the contribution from local sources; 
identification of the relevant SIP or other enforceable control 
measures in place for these sources and the implementation status of 
these controls; and evidence of effective implementation and 
enforcement of the identified enforceable control measures.\27\ In 
addressing the not reasonably controllable or preventable criterion, 
deference is given to measures in a SIP approved 5 years or less prior 
to the event and addresses the event-related pollutant and all relevant 
sources.\28\
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    \27\ EPA, Office of Air Quality Planning and Standards, Guidance 
on the Preparation of Demonstrations in Support of Requests to 
Exclude Ambient Air Quality Data Influenced by High Wind Dust Events 
Under the 2016 Exceptional Events Rule, EPA-457/B-19-001, April 
2019, page 11.
    \28\ 40 CFR 50.14(b)(8)(v).
---------------------------------------------------------------------------

    For concurred events between 2014 and 2017, the EPA had approved 
the PM10 SIP for the Imperial County PM10 
nonattainment area within the previous 5 years; it is therefore 
presumed that there were reasonable controls for local sources in place 
at the time of the event. For concurred 2018 events where the 
applicable SIP's approval date was more than 5 years from the event, 
the demonstrations provided additional information indicating that 
there were reasonable controls for local sources in place at the time 
of the event, and the EPA further assessed controls in the addendum to 
the relevant Technical Support Documents (TSDs). Finally, the 
demonstrations also provided evidence of effective implementation and 
enforcement of the relevant controls. As further outlined in the EPA 
TSDs, the EPA therefore concluded that the not reasonably controllable 
or preventable criterion was met for all concurred events.

III. Final Action

    Under CAA section 110(k)(3), for the reasons set forth in this 
final rule and in our proposed rule, the EPA is approving the Imperial 
PM10 Plan submitted by CARB by letter dated February 6, 
2019, as a revision to the California SIP. In so doing, the EPA is 
approving the BACM demonstration and attainment inventory included as 
part of the Imperial PM10 Plan as meeting the requirements 
of CAA sections 189(b)(1)(B) and 172(c)(3), respectively. We are 
approving the maintenance demonstration and contingency provisions as 
meeting all applicable requirements for maintenance plans and related 
contingency provisions in CAA section 175A. The EPA is also approving 
the motor vehicle emissions budgets for 2016 and 2030 (shown in Table 
1, above) because we find they meet all applicable criteria for such 
budgets including the adequacy criteria under 40 CFR 93.118(e) and is 
determining that the submitted 2016 and 2030 budgets included in the 
Imperial PM10 Plan (20 tpd and 19 tpd, respectively) are 
adequate for transportation conformity purposes.\29\
---------------------------------------------------------------------------

    \29\ Pursuant to 40 CFR 93.118(f)(2)(iii), the EPA's adequacy 
determination is effective upon publication of this final rule in 
the Federal Register.
---------------------------------------------------------------------------

    In addition, under CAA section 107(d)(3)(D), we are approving 
CARB's request to redesignate the Imperial PM10 Planning 
Area from nonattainment to attainment for the PM10 NAAQS. We 
are doing so based on our conclusion that the area has met, or will 
meet as part of this action, all the criteria for redesignation under 
CAA section 107(d)(3)(E). More specifically, we find the following: 
That the Imperial PM10 nonattainment area has attained the 
PM10 standard based on quality-assured, certified, and 
complete PM10 data; \30\ that relevant portions of the 
California SIP are, or will be as part of this action, fully approved; 
that the improvement in air quality is due to permanent and enforceable 
reductions in emissions; that California has met all requirements 
applicable to the Imperial PM10 nonattainment area with 
respect to section 110 and part D of the CAA given our approvals of the 
BACM demonstration and the attainment inventory in the Imperial 
PM10 Plan, as finalized herein; and that the Imperial 
PM10 nonattainment area will have a fully approved 
maintenance plan meeting the requirements of CAA section 175A, as 
finalized herein. In connection with the above approvals and 
determinations, and as authorized under CAA section 189(e), we are 
determining that PM10 precursors do not contribute 
significantly to PM10 exceedances in the Imperial 
PM10 nonattainment area.
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    \30\ The proposed determination of attainment in the proposed 
rule was based on quality-assured, certified, and complete data 
(2014-2018) available at that time. Since publication of the 
proposed rule, CARB and ICAPCD have certified year 2019 data, and we 
find that the data collected in 2019 are consistent with continued 
attainment of the PM10 NAAQS in the Imperial Valley 
Planning Area. In addition, we have reviewed preliminary data 
collected from January through June 2020 and find that they too are 
consistent with continued attainment.
---------------------------------------------------------------------------

IV. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan under section 107(d)(3)(E) 
are actions that affect the status of a geographic area and do not 
impose any additional regulatory requirements on sources beyond those 
imposed by state law. Redesignation to attainment does not in and of 
itself create any new requirements, but rather results in the 
applicability of requirements contained in the CAA for areas that have 
been redesignated to attainment. Moreover, 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 action merely approves a State plan and redesignation 
request as meeting federal requirements and do not impose additional 
requirements beyond those imposed by state law. For these reasons, this 
action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);

[[Page 58293]]

     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide the EPA with the discretionary authority 
to address, as appropriate, disproportionate human health or 
environmental effects, using practicable and legally permissible 
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the State plan the EPA is approving does not apply on 
any Indian reservation land or in any other area where the EPA or an 
Indian tribe has demonstrated that a tribe has jurisdiction. In those 
areas of Indian country, the rule, as it relates to the maintenance 
plan, does not have tribal implications and will not impose substantial 
direct costs on tribal governments or preempt tribal law as specified 
by Executive Order 13175 (65 FR 67249, November 9, 2000). However, the 
redesignation does apply to Indian country within the nonattainment 
area. In those areas of Indian country, the redesignation action will 
not result in the relaxation of measures and programs currently in 
place to protect air quality and will not impose substantial direct 
costs on tribal governments or preempt tribal law as specified by 
Executive Order 13175 (65 FR 67249, November 9, 2000). The EPA invited 
the Torres Martinez Desert Cahuilla Indians and the Quechan Tribe of 
the Fort Yuma Indian Reservation, who have lands within the Imperial 
PM10 nonattainment area, to consult on this action. The 
Torres Martinez Desert Cahuilla Indians accepted our invitation, and 
consultation was conducted on December 8, 2019 and on January 6, 2020.
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. The EPA will submit a report containing this action and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by November 17, 2020. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review nor does it extend the time within which a petition for 
judicial review may be filed, and shall not postpone the effectiveness 
of such rule or action. This action may not be challenged later in 
proceedings to enforce its requirements. (See section 307(b)(2).)

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Particulate 
matter, Reporting and recordkeeping requirements, Sulfur oxides, 
Volatile organic compounds.

40 CFR Part 81

    Environmental protection, Air pollution control, National parks, 
Wilderness areas.

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

    Dated: August 17, 2020.
John Busterud,
Regional Administrator, Region IX.
    Chapter I, title 40 of the Code of Federal Regulations is amended 
as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

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

Subpart F--California

0
2. Section 52.220 is amended by adding paragraph (c)(541) to read as 
follows:


Sec.  52.220  Identification of plan--in part.

* * * * *
    (c) * * *
    (541) The following plan was submitted on February 13, 2019 by the 
Governor's designee as an attachment to a letter dated February 6, 
2019.
    (i) [Reserved]
    (ii) Additional materials. (A) Imperial County Air Pollution 
Control District.
    (1) Imperial County 2018 Redesignation Request and Maintenance Plan 
for Particulate Matter Less Than 10 Microns in Diameter, adopted 
October 23, 2018, excluding appendix B (``Executed Settlement 
Agreement'') and appendix F (``Regulation VIII Fugitive Dust Rules'').
    (2) [Reserved]

PART 81--DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES

0
3. The authority citation for part 81 continues to read as follows:

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

Subpart C--Section 107 Attainment Status Designations

0
4. Section 81.305 is amended in the table entitled ``California--PM-
10,'' by revising the entries for ``Imperial County'' and ``Imperial 
Valley planning area: That portion of Imperial County that is defined 
as follows:'' to read as follows:


Sec.  81.305  California.

* * * * *

                                                California--PM-10
----------------------------------------------------------------------------------------------------------------
                                                         Designation                      Classification
              Designated area              ---------------------------------------------------------------------
                                                 Date               Type               Date            Type
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Imperial County:
    Imperial Valley planning area: That         10/19/2020  Attainment..........  ..............  ..............
     portion of Imperial County that is
     defined as follows:.

[[Page 58294]]

 
        Commencing at the southwest corner  ..............  ....................  ..............  ..............
         of Imperial County and extending
         north along the Imperial-San
         Diego County line to the
         northwest corner of Imperial
         County; then east along the
         Imperial-Riverside County line to
         the point of intersection of the
         eastern boundary line of
         Hydrologic Unit #18100200; then
         southeasterly along the eastern
         boundary line of Hydrologic Unit
         #18100200 to the Imperial County-
         Mexico Border; then west along
         the Imperial County-Mexico Border
         to the point of the beginning..
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *
[FR Doc. 2020-18427 Filed 9-16-20; 4:15 pm]
BILLING CODE 6560-50-P