Document ID: EPA-R10-OAR-2020-0190-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Idaho: Logan Utah-Idaho Fine Particulate Matter Redesignation to Attainment and Maintenance Plan
Posted Date: 2021-02-17T05:00Z

[Federal Register Volume 86, Number 30 (Wednesday, February 17, 2021)]
[Proposed Rules]
[Pages 9884-9893]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-03031]

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 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 86, No. 30 / Wednesday, February 17, 2021 / 
Proposed Rules  

[[Page 9884]]

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R10-OAR-2020-0190; FRL-10014-37-Region 10]

Air Plan Approval; ID: Logan Utah-Idaho PM2.5 Redesignation to 
Attainment and Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
redesignate the Idaho portion of the Logan, Utah-Idaho fine particulate 
matter (PM2.5) nonattainment area (Logan UT-ID NAA) to 
attainment for the 2006 PM2.5 National Ambient Air Quality 
Standard (NAAQS). EPA is also proposing to approve a maintenance plan 
for the area demonstrating continued compliance with the 2006 
PM2.5 NAAQS through 2031, which the Idaho Department of 
Environmental Quality (IDEQ) submitted along with the redesignation 
request on September 13, 2019, for inclusion into the Idaho State 
Implementation Plan (SIP). Additionally, EPA is proposing to approve 
the 2031 motor vehicle emissions budgets included in Idaho's 
maintenance plan for PM2.5, nitrogen oxides (NOX) 
and volatile organic compounds (VOC). EPA is proposing this action 
pursuant to the Clean Air Act (CAA or the Act).

DATES: Comments must be received on or before March 19, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2020-0190, at https://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. EPA may publish any comment 
received to its public docket. Do not electronically submit any 
information you consider to be Confidential Business Information (CBI) 
or other information the disclosure of which 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. 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, the full EPA public comment 
policy, information about CBI or multimedia submissions, and general 
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Adam Clark, (206) 553-1495, 
clark.adam@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, it is intended to refer to EPA.

Table of Contents

I. Background
II. Requirements for Redesignation to Attainment
III. EPA's Analysis of Idaho's Submittal
    A. Attainment Determination
    B. Applicable Requirements Under Section 110 and Part D of the 
CAA
    1. CAA Section 110 General SIP Requirements
    2. Part D of Title I Requirements
    3. Fully Approved SIP Under CAA Section 110(k)
    C. Improvement in Air Quality Due to Permanent and Enforceable 
Measures
    D. Fully Approved Maintenance Plan
    1. Attainment Inventory
    2. Maintenance Demonstration
    3. Monitoring Network
    4. Verification of Continued Attainment
    5. Contingency Plan
    E. Requirements for Transportation Conformity and Motor Vehicle 
Emissions Budgets (MVEBs)
IV. Proposed Action
V. Statutory and Executive Order Reviews

I. Background

    On October 17, 2006 (71 FR 61144), EPA revised the level of the 24-
hour PM2.5 NAAQS, lowering the primary and secondary 
standards from the 1997 standard of 65 micrograms per cubic meter 
([micro]g/m\3\) to 35 [micro]g/m\3\. On November 13, 2009, EPA 
designated a portion of Franklin County, Idaho in addition to portions 
of Cache County, Utah nonattainment for the 2006 24-hour 
PM2.5 NAAQS (74 FR 58688). This cross-boundary nonattainment 
area is referred to as the Logan, UT-ID PM2.5 NAA.
    The boundaries of the Logan, UT-ID PM2.5 NAA roughly 
conform to the geographic boundaries of the Cache Valley. The Cache 
Valley is an isolated, bowl-shaped valley measuring approximately 60 
kilometers north to south and 20 kilometers east to west and almost 
entirely surrounded by mountain ranges. The Wellsville Mountains lie to 
the west, and on the east lie the Bear River Mountains; both are 
northern branches of the Wasatch Range. This topography can act as a 
barrier to air movement in the Cache Valley during temperature 
inversions, which occur in the winter months and are often the cause of 
elevated concentrations of fine particulates. Additional information 
pertaining to the unique issues associated with the Logan, UT-ID 
PM2.5 NAA and studies completed on inversions can be found 
in the docket for Utah and Idaho in the November 13, 2009, final 
designations action for the 2006 24-Hour PM2.5 NAAQS (74 FR 
58688).
    The nonattainment designation of the Logan UT-ID PM2.5 
NAA required Idaho to prepare and submit an attainment plan to meet 
statutory and regulatory requirements in the Idaho portion of the 
Logan, UT-ID PM2.5 NAA.\1\ IDEQ submitted this attainment 
plan to EPA on December 14, 2012, and supplemented the attainment plan 
on December 24, 2014. The attainment plan addressed specific required 
elements, including but not limited to the following elements: 
Emissions inventory, Reasonably Available Control Measures/Technology 
(RACM/RACT), attainment demonstration, contingency measures, and Motor 
Vehicle Emissions Budgets (MVEBs). EPA approved the baseline emissions 
inventory on July 18, 2014 (79 FR 41904) and the control measures on 
March 25, 2014 (79 FR 16201). EPA approved the control measures in the 
attainment plan as meeting RACM/RACT and disapproved contingency 
measures on January 4, 2017 (82 FR 729). EPA approved the attainment 
demonstration on August 8,

[[Page 9885]]

2017 (82 FR 37025). We also approved a separate, March 20, 2018, Idaho 
SIP revision as meeting applicable part D nonattainment new source 
review (NSR) requirements on August 20, 2018 (83 FR 42033).\2\ Most 
recently, we approved the attainment plan as meeting the Reasonable 
Further Progress (RFP), Quantitative Milestone (QM), and MVEB 
requirements on February 20, 2020 (85 FR 9664).
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    \1\ See part D of title I of the Clean Air Act and EPA's Fine 
Particulate Matter National Ambient Air Quality Standards: State 
Implementation Plan Requirements (72 FR 20586, April 25, 2007).
    \2\ Idaho's submission incorporated by reference EPA's August 
24, 2016 (81 FR 58010) rule changes to 40 CFR 51.165 promulgated 
under CAA subpart 4, part D.
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    On September 8, 2017 (82 FR 42447), EPA granted two, one-year 
extensions, under CAA section 188(d), to the December 31, 2015 Moderate 
attainment date for the 2006 24-hour PM2.5 Logan, UT-ID NAA. 
On October 19, 2018, EPA finalized a determination that the Logan, UT-
ID PM2.5 NAA had attained the 2006 primary and secondary 24-
hour PM2.5 NAAQS (``Determination of Attainment'') by the 
December 31, 2017, attainment date (83 FR 52983). Additionally, EPA 
finalized a determination that the obligation to submit any remaining 
attainment-related SIP revisions arising from classification of the 
Logan, UT-ID NAA as Moderate under subpart 4 of part D (of title I of 
the Act) for the 2006 24-hour PM2.5 NAAQS are not applicable 
for so long as the area continues to attain the 2006 24-hour 
PM2.5 NAAQS. See 40 CFR 51.1015(a) (known as a ``Clean Data 
Determination'' or ``CDD'').

II. Requirements for Redesignation to Attainment

    The CAA provides the requirements for redesignating a nonattainment 
area to attainment. Specifically, section 107(d)(3)(E) of the CAA, 42 
U.S.C. 7407(d)(3)(E), allows for redesignation provided that: (1) EPA 
determines that the area has attained the applicable NAAQS; (2) EPA has 
fully approved the applicable implementation plan for the area under 
section 110(k) of the CAA; (3) EPA determines that the improvement in 
air quality is due to permanent and enforceable reductions in emissions 
resulting from implementation of the applicable SIP and applicable 
federal air pollutant control regulations and other permanent and 
enforceable reductions; (4) EPA has fully approved a maintenance plan 
for the area as meeting the requirements of section 175A of the CAA; 
and (5) the state containing such area has met all requirements 
applicable to the area under section 110 and part D of the CAA. In this 
proposed action, EPA will review CAA section 107(d)(3)(E) requirements 
(2) and (5) together as part of our evaluation of Idaho's redesignation 
request.
    EPA has provided guidance on redesignation in the ``General 
Preamble,'' \3\ and has provided further guidance on processing 
redesignation requests in the following documents: (1) ``Procedures for 
Processing Requests to Redesignate Areas to Attainment,'' Memorandum 
from John Calcagni, Director, Air Quality Management Division, 
September 4, 1992 (hereafter the ``Calcagni Memo''); (2) ``State 
Implementation Plan (SIP) Actions Submitted in Response to Clean Air 
Act (CAA) Deadlines,'' Memorandum from John Calcagni, Director, Air 
Quality Management Division, October 28, 1992; and (3) ``Part D New 
Source Review (Part D NSR) Requirements for Areas Requesting 
Redesignation to Attainment,'' Memorandum from Mary D. Nichols, 
Assistant Administrator for Air and Radiation, October 14, 1994. These 
documents are included in the Docket for this proposed action.
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    \3\ See ``State Implementation Plans; General Preamble for the 
Implementation of Title I of the Clean Air Act Amendments of 1990,'' 
57 FR 13498, April 16, 1992.
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III. EPA's Analysis of Idaho's Submittal

    EPA is proposing to redesignate the Franklin County, ID portion of 
the Logan UT-ID NAA to attainment for the 2006 24-hour PM2.5 
NAAQS and proposing to approve into the Idaho SIP the associated 
maintenance plan. EPA's proposed approval of the redesignation request 
and maintenance plan is based upon EPA's determination that the area 
continues to attain the 2006 24-hour PM2.5 NAAQS and that 
all other redesignation criteria have been met for the area. The 
following is a description of how Idaho's September 13, 2019, submittal 
satisfies the requirements of section 107(d)(3)(E) of the CAA for the 
2006 24-hour PM2.5 standard.

A. Attainment Determination

    To redesignate an area from nonattainment to attainment, the CAA 
requires EPA to determine that the area has attained the applicable 
NAAQS (CAA section 107(d)(3)(E)(i)). Whether an area has attained the 
2006 24-hour PM2.5 NAAQS is based upon measured air quality 
levels at each eligible monitoring site with a complete three-year 
period to produce a design value equal to or below 35 [micro]g/m\3\. 
See 40 CFR part 50 and 40 CFR part 50, appendix N. A state must 
demonstrate that an area has attained the 2006 24-hour PM2.5 
NAAQS through submittal of ambient air quality data from an ambient air 
monitoring network representing maximum PM2.5 
concentrations. The data must be quality assured, quality-controlled 
and certified in the EPA's Air Quality System (AQS) and it must show 
that the three-year average of valid PM2.5 98th percentile 
mass concentrations is equal to or below the 2006 24-hour 
PM2.5 NAAQS (35 [micro]g/m\3\), pursuant to 40 CFR 50.13. In 
making this showing, three consecutive years of complete air quality 
data must be used.
    As noted, on October 19, 2018, EPA finalized a Determination of 
Attainment for the Logan, UT-ID PM2.5 NAA based upon 
quality-assured and certified ambient air quality monitoring data for 
the period of 2015-2017 (83 FR 52983). The monitoring data used as the 
basis for the Determination of Attainment under CAA section 188(b)(2) 
is provided in Table 1 of this document.
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    \4\ See 83 FR 52983, October 19, 2018.

                            Table 1--Logan UT-ID Area Design Values From 2018 CDD \4\
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                                                       98th percentile value ([micro]g/m\3\)
             Monitor                AQS site ID  ------------------------------------------------    2015-2017
                                                       2015            2016            2017        design value
----------------------------------------------------------------------------------------------------------------
Smithfield, UT..................       490050007        \a\ 28.9            34.0            36.0          \a\ 33
Franklin, ID....................       160410001            18.8            33.3        \b\ 38.3          \b\ 30
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\a\ This value combines monitor data from the Logan, UT and Smithfield, UT monitors. EPA concurred on
  exceptional events in the October 19, 2018 (83 FR 52983) action and the specified data was excluded.
\b\ This value includes 1-in-3 day monitoring frequency from January 1-August 9, 2017, and daily monitoring
  frequency from August 10-December 31, 2017.

[[Page 9886]]

    EPA has also reviewed the subsequent PM2.5 ambient air 
monitoring data in the Logan UT-ID area for the monitoring design value 
\5\ periods of 2016-2018 and 2017-2019. Consistent with the 
requirements at 40 CFR part 50, Idaho quality assured, quality-
controlled and certified this ambient air monitoring data in the EPA's 
Air Quality System (AQS). This air quality data demonstrates that the 
Logan UT-ID area continues to attain the 2006 24-hour PM2.5 
NAAQS. For the 2016-2018 three-year period, the Smithfield monitor 
recorded a design value of 33 [micro]g/m\3\.\6\ The area's 24-hour 
PM2.5 design values for the 2017-2019 three-year period are 
provided in Table 2 of this document.
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    \5\ As defined in 40 CFR part 50, Appendix N, section (1)(c).
    \6\ See https://www.epa.gov/air-trends/air-quality-design-values#report.
    \7\ The Preston monitor does not have a valid design value for 
the 2017-2019 three-year period because of an incomplete 2017 
quarter 1 which cannot be substituted with quarter 1 data at the 
same monitor in 2018 or 2019 per 40 CFR part 50, Appendix N, section 
4.2(c)(i) because it has below 50% complete data for that quarter.

                              Table 2--Logan UT-ID Current PM2.5 Design Values \7\
----------------------------------------------------------------------------------------------------------------
                                                       98th percentile value ([micro]g/m\3\)       Design value
             Monitor                AQS site ID  ------------------------------------------------     (3-year
                                                       2017            2018            2019          average)
----------------------------------------------------------------------------------------------------------------
Smithfield, UT..................       490050007            36.0            27.9            35.1              33
Preston, ID.....................       160410002        \a\ 17.3            27.2            30.1          \b\ NA
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\a\ The Preston monitor operated at a 1-in-3 day monitoring frequency throughout 2017 and did not begin
  operation until February 24, 2017, making the first quarter incomplete for this monitor with less than 50% of
  data reported.
\b\ Due to the incomplete first quarter in 2017, this design value does not meet validity requirements per 40
  CFR part 50, Appendix N, section 4.2(c)(i).

    As Table 2 indicates, the Logan UT-ID PM2.5 NAA has 
continued to attain the 2006 24-hour PM2.5 NAAQS since EPA 
issued its October 19, 2018, Determination of Attainment for the area 
based on the 2015-2017 design values shown in Table 1 of this document. 
We note that the Preston, ID monitor did not produce a valid design 
value for the 2017-2019 period because the monitor did not begin 
operation until February 24, 2017, thus producing an incomplete first 
quarter for that monitoring year. Despite this, EPA finds that it is 
appropriate to conclude that the area has continued to attain the NAAQS 
since the initial 2015-2017 period upon which we based our October 19, 
2018, Determination of Attainment, based on uninterrupted attainment at 
the Smithfield, UT monitor. A review of concurrent monitoring data for 
the Smithfield and Preston monitors provided in Table 2 of this 
document, and discussed in more detail in our Technical Support 
Document (TSD) \8\ included in the docket for this proposed action, 
shows that the Smithfield site typically records higher levels of 
PM2.5 than the Preston site, indicating that Smithfield's 
location is more suitable to demonstrate maximum PM2.5 
concentrations in the Cache Valley. On September 1, 2020, Utah and 
Idaho completed a memorandum of understanding (MOU) to collectively 
meet the monitoring requirements of 40 CFR part 58, Appendix D in the 
Logan UT-ID metropolitan statistical area (MSA), allowing Idaho to rely 
on the Smithfield monitor in Utah as the highest concentration monitor 
in the MSA. As shown, the Smithfield monitor has attained the 2006 24-
hour PM2.5 NAAQS for the 2015-2017, 2016-2018 and 2017-2019 
design value periods. The MOU is included in the docket for this 
proposed action. The TSD also demonstrates that it is very unlikely 
that the Preston monitor's first complete valid design value for the 
2018-2020 period could exceed the 2006 PM2.5 NAAQS based on 
a review of all available data recorded at this monitor.
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    \8\ Please see ``EPA R10 Ambient Monitoring TSD'' in the docket 
for this proposed action (EPA-R10-OAR-2020-0190) on 
www.regulations.gov.
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    EPA's review of the monitoring data for 2016-2018 and 2017-2019 
supports the previous determination that the area has attained the 2006 
24-hour PM2.5 NAAQS and demonstrates that the area continues 
to attain the standard. As discussed further in Section III.D of this 
document, Idaho has committed to continue monitoring ambient 
PM2.5 concentrations in accordance with 40 CFR part 58. 
Thus, EPA is proposing to determine that the Logan UT-ID 
PM2.5 NAA attained the 2006 24-hour PM2.5 NAAQS.

B. Applicable Requirements Under Section 110 and Part D of the CAA

    Section 107(d)(3)(E)(ii) and (v) of the CAA states that for an area 
to be redesignated to attainment, it must be determined that the 
Administrator has fully approved the applicable implementation plan for 
the area under CAA section 110(k) and all the requirements applicable 
to the Area under section 110 of the CAA (general SIP requirements) and 
part D of Title I of the CAA (SIP requirements for nonattainment areas) 
must be met.
1. CAA Section 110 General SIP Requirements
    Section 110(a)(2) of Title I of the CAA delineates the general 
requirements for a SIP, which include enforceable emissions limitations 
and other control measures, means or techniques, provisions for the 
establishment and operation of appropriate devices necessary to collect 
data on ambient air quality, and programs to enforce the limitations. 
The general SIP elements and requirements set forth in CAA section 
110(a)(2) include, but are not limited to the following:
     Submittal of a SIP that has been adopted by the state 
after reasonable public notice and hearing;
     Provisions for establishment and operation of appropriate 
procedures needed to monitor ambient air quality;
     Implementation of a source permit program; provisions for 
the implementation of Part C requirements (PSD);
     Provisions for the implementation of Part D requirements 
for NSR permit programs;
     Provisions for air pollution modeling; and
     Provisions for public and local agency participation in 
planning and emission control rule development.
    CAA section 110(a)(2)(D) requires that SIPs contain certain 
measures to prevent sources in a state from significantly contributing 
to air quality problems in another state. However, CAA section 
110(a)(2)(D) requirements for a state are not linked with a particular 
nonattainment area's designation and classification in that state. EPA 
believes that the requirements linked with a

[[Page 9887]]

particular nonattainment area's designation and classifications are the 
relevant measures to evaluate in reviewing a redesignation request. The 
transport SIP submittal requirements, where applicable, continue to 
apply to a state regardless of the designation of any one particular 
area in the state. Thus, EPA does not believe that these requirements 
are applicable requirements for purposes of redesignation.
    In addition, EPA believes that the other CAA section 110(a)(2) 
elements not connected with nonattainment plan submissions and not 
linked with an area's attainment status are not applicable requirements 
for purposes of redesignation because the area will still be subject to 
these requirements after it is redesignated. EPA concludes that the CAA 
section 110(a)(2) and part D requirements which are linked with a 
particular area's designation and classification are the relevant 
measures to evaluate in reviewing a redesignation request, and that CAA 
section 110(a)(2) elements not linked to the area's nonattainment 
status are not applicable for purposes of redesignation. This approach 
is consistent with EPA's existing policy on applicability of conformity 
(i.e., for redesignations) and oxygenated fuels requirement. See 
Reading, Pennsylvania, proposed and final rulemakings (61 FR 53174, 
October 10, 1996), (62 FR 24826, May 7, 1997); Cleveland-Akron-Lorain, 
Ohio final rulemaking (61 FR 20458, May 7, 1996); and Tampa, Florida, 
final rulemaking (60 FR 62748, December 7, 1995). See also, the 
discussion on this issue in the Cincinnati, Ohio redesignation (65 FR 
at 37890, June 19, 2000), and in the Pittsburgh-Beaver Valley, 
Pennsylvania redesignation (66 FR at 53099, October 19, 2001).
    EPA has reviewed the Idaho SIP and has concluded that it meets the 
general SIP requirements under Section 110(a)(2) of the CAA to the 
extent they are applicable for the purposes of redesignation. EPA has 
previously approved provisions of Idaho's SIP as demonstrating 
compliance with the CAA section 110(a)(2) requirements for the 2006 
PM2.5 NAAQS (79 FR 40662, July 14, 2014). These requirements 
are, however, statewide requirements that are not linked to the 
PM2.5 nonattainment status of the Logan, UT-ID NAA. 
Therefore, EPA believes that these SIP elements are not applicable 
requirements for purposes of review of this proposed redesignation.
2. Part D of Title I Requirements
    Part D of Title I of the CAA sets forth the basic nonattainment 
plan requirements applicable to all nonattainment areas at subpart 1 
(CAA sections 172-176) and requirements specific to PM10 and 
PM2.5 areas at subpart 4 (CAA section 189). On August 24, 
2016, EPA promulgated the Fine Particulate Matter National Ambient Air 
Quality Standards; State Implementation Plan Requirements rule.\9\ This 
rule implements the requirements of Part D of Title I of the CAA for 
areas designated nonattainment for any PM2.5 NAAQS.
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    \9\ 81 FR 58010, August 24, 2016. Codified at 40 CFR part 51, 
subpart Z.
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    In accordance with 40 CFR 51.1015, upon a determination by EPA that 
a Moderate PM2.5 nonattainment area has attained the 
PM2.5 NAAQS, the requirements for the state to submit an 
attainment demonstration, provisions demonstrating that RACM (including 
RACT for stationary sources) shall be implemented no later than 4 years 
following the date of designation of the area, RFP plan, QMs and QM 
reports, and contingency measures for the area shall be suspended until 
such time as: (1) The area is redesignated to attainment, after which 
such requirements are permanently discharged; or, (2) EPA determines 
that the area has re-violated the PM2.5 NAAQS.
    Those states containing Moderate PM2.5 NAAs were 
required to submit a SIP by December 31, 2014, which demonstrated 
attainment of the PM2.5 NAAQS by December 31, 2015.\10\ 
Pursuant to CAA section 188(d) and 40 CFR 51.1005(a), on September 8, 
2017, EPA extended the attainment date for the Logan UT-ID NAA from 
December 31, 2015 to December 31, 2017 (82 FR 42447). As stated in the 
``Background'' section, EPA has approved several attainment plan 
elements for the Idaho portion of the Logan UT-ID area. Specifically, 
EPA approved the following elements of Idaho's attainment plan: 
Baseline emissions inventory (July 18, 2014, 79 FR 41904); control 
measures (March 25, 2014, 79 FR 16201); RACM/RACT (January 4, 2017, 82 
FR 729); attainment demonstration (August 8, 2017, 82 FR 37025); 
nonattainment NSR (August 20, 2018, 83 FR 42033), and RFP, QM and MVEB 
(February 20, 2020, 85 FR 9664).
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    \10\ See Section 188(c)(1) of the CAA, 42 U.S.C. 7513(c)(1), 40 
CFR 51.1004(a)(1). See also Identification of Nonattainment 
Classification and Deadlines for Submission of State Implementation 
Plan (SIP) Provisions for the 1997 Fine Particle (PM2.5) 
National Ambient Air Quality Standard (NAAQS) and 2006 
PM2.5 NAAQS (June 2, 2014), 79 FR 31566, 31567-68.
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    Pursuant to 40 CFR 51.1015(a), on October 19, 2018, EPA completed a 
CDD for the Logan, UT-ID Moderate PM2.5 NAA. (83 FR 52983). 
The CDD suspended the obligation for Idaho to make submissions to meet 
certain CAA requirements related to attainment of the NAAQS, including 
the CAA section 172(c)(9) requirement to adopt contingency measures.
    Determinations of attainment do not relieve states from submitting 
and EPA from approving certain Part D planning requirements for the 
2006 PM2.5 NAAQS. CAA section 172(c)(3) requires submission 
and approval of a comprehensive, accurate and current inventory of 
actual emissions. For purposes of the PM2.5 NAAQS, this 
emissions inventory should address not only direct emissions of 
PM2.5, but also emissions of all precursors to 
PM2.5 formation, i.e., SO2, NOX, VOC, 
and ammonia. As previously discussed, EPA determined that Idaho met the 
CAA section 172(c)(3) comprehensive emissions inventory requirement in 
a final rulemaking on July 18, 2014 (79 FR 41904).
    CAA section 172(c)(4) requires the identification and 
quantification of allowable emissions for major new and modified 
stationary sources in an area, and CAA section 172(c)(5) and requires 
source permits for the construction and operation of new and modified 
major stationary sources anywhere in the nonattainment area. EPA first 
approved the requirements of the part D NSR permit program for Idaho 
under subpart 1 on November 26, 2010 (75 FR 72719). Subsequently, on 
March 20, 2018, Idaho submitted rule revisions to meet additional part 
D NSR requirements promulgated by the EPA under subpart 4 (81 FR 58010, 
August 24, 2016). We approved Idaho's submission on August 20, 2018 (83 
FR 42033).
    Once the Logan, UT-ID PM2.5 NAA is redesignated to 
attainment, the prevention of significant deterioration (PSD) 
requirements of part C of the Act will apply. Idaho's PSD regulations 
are codified in the Idaho Administrative Procedures Act (IDAPA) at 
58.01.01.200-228 (permit to construct) and governed by IDAPA 
58.01.01.205 (permit requirements for new major facilities or major 
modifications in attainment or unclassifiable areas). We most recently 
approved revisions to Idaho's PSD program on August 20, 2018 (83 FR 
42033), May 12, 2017 (82 FR 22083) and August 12, 2016 (81 FR 53290). 
EPA finds that Idaho's PSD provisions meet all applicable Federal 
requirements for any area designated unclassifiable or attainment, and 
these provisions will become fully effective in the Idaho portion of 
the Logan, UT-ID

[[Page 9888]]

PM2.5 NAA upon redesignation of the area to attainment.
    CAA section 172(c)(7) requires the SIP to meet the applicable 
provisions of CAA section 110(a)(2). As noted above, we find that the 
Idaho SIP meets the CAA section 110(a)(2) applicable requirements for 
purposes of redesignation.
    For purposes of redesignation to attainment for the 2006 24-hour 
PM2.5 NAAQS, EPA proposes to find that Idaho has met all the 
applicable SIP requirements under part D of Title I of the CAA.
3. Fully Approved SIP Under CAA Section 110(k)
    As discussed in Sections III.B.1 and III.B.2 of this document, for 
purposes of redesignation to attainment for the 2006 24-hour 
PM2.5 NAAQS, EPA has fully approved all applicable 
requirements of Idaho's SIP for the Idaho portion of the Logan UT-ID 
area in accordance with CAA section 110(k). Therefore, EPA has fully 
approved all applicable requirements of the applicable implementation 
plan in accordance with CAA section 110(k).

C. Improvement in Air Quality Due to Permanent and Enforceable Measures

    CAA section 107(d)(3)(E)(iii) of the CAA provides that for an area 
to be redesignated to attainment, the Administrator must determine that 
the improvement in air quality is due to permanent and enforceable 
reductions in emissions resulting from implementation of the applicable 
implementation plan, implementation of applicable Federal air pollutant 
control regulations, and other permanent and enforceable reductions.
    On December 14, 2012, IDEQ submitted an attainment plan that 
addressed attainment planning requirements for the Idaho portion of the 
Logan UT-ID PM2.5 NAA. On December 24, 2014, the IDEQ 
submitted a supplement to the 2012 attainment plan that included 
additional analysis. Idaho's December 14, 2012, attainment plan 
submittal included residential wood combustion (RWC) ordinances, road-
sanding agreements, and a wood stove change-out program to reduce 
emissions of PM2.5 in the Idaho portion of the Logan UT-ID 
PM2.5 NAA. Each of these programs is discussed in detail 
within this section. EPA approved the RWC ordinances and road sanding 
agreements into the Idaho SIP on March 25, 2014 (79 FR 16201), making 
them federally enforceable. EPA approved Idaho's evaluation of, and 
imposition of, RACM and RACT level controls on appropriate sources on 
January 4, 2017 (82 FR 729). This approval included approving the RWC 
ordinances and wood stove change-out program as meeting the RACM 
requirement.
    The RWC ordinances approved as RACM on January 4, 2017, apply 
within Franklin County and all six Idaho cities on the Idaho side of 
the Logan UT-ID PM2.5 NAA (Franklin, Preston, Weston, 
Dayton, Clifton, and Oxford). EPA determined in its approvals that 
these RWC ordinances achieved permanent and enforceable emissions 
reductions. Key elements in the current RWC ordinances include 
mandatory burn bans issued when PM2.5 has reached or is 
forecasted to reach 75 on the Air Quality Index (AQI), which 
corresponds to a PM2.5 concentration of 23.3 [mu]g/m\3\ and 
aligns with the RWC ordinances applicable within Cache County on the 
Utah side of the Logan UT-ID PM2.5 NAA. All RWC ordinances 
effective in Franklin County prohibit both open burning and the use of 
specified devices when an air quality alert is issued. The ordinances 
also prohibit the installation of non-EPA-certified devices. Each of 
the adopted ordinances bans open burning of any kind during burn ban 
days, bans the sale or installation of non-EPA certified devices in new 
or existing buildings, and prohibits the construction of any building 
for which a solid fuel burning device is the sole source of heat. In 
its December 14, 2012, attainment plan submittal, Idaho estimated that 
maximum reductions for this measure are 0.06 tons per day (tpd) direct 
PM2.5, 0.009 tpd nitrogen oxides (NOX), and 0.078 
tpd volatile organic compounds (VOC).
    In our March 25, 2014 action, EPA also approved road sanding 
agreements between IDEQ, Franklin County Road and Bridge, and the Idaho 
Transportation Department (IDT) to reduce the contribution of primary 
PM2.5 from reentrained dust on paved roads. According to 
records submitted to Idaho and summarized in the submission, IDT used 
salt in 2014 (409 tons), 2015 (340 tons), and 2016 (109 tons) and did 
not use sand. Franklin County Road and Bridge historically used a 10:1 
ratio of sand and salt; however, in the Idaho attainment plan, Franklin 
County committed to use a 4:1 ratio of sand and salt when anti-skid 
treatment is required. Franklin County also agreed to apply brine when 
temperatures are above 22 [deg]F, a measure that further reduces the 
amount of sand required by approximately 50%. The City of Preston now 
uses a 2:1 ratio of sand and salt at an average of 700 tons total per 
year. In its SIP, IDEQ estimates that these road sanding commitments 
would lead to 0.10 tpd reduction in direct PM2.5 annually.
    Finally, in its attainment plan, IDEQ quantified the emission 
reduction benefits from three woodstove change-out programs on the 
Idaho side of the Logan UT-ID area. These programs were conducted in 
2006-2007, 2011-2012, and 2013-2014. Accordingly, Idaho demonstrated in 
the submission that a total of 209 uncertified RWC devices have been 
changed-out since 2006. In addition, 39 stoves were removed and 
destroyed through Idaho's Alternative Energy Device tax deduction 
program. In total, 256 wood stoves have been changed out on the Idaho 
side of the Logan UT-ID NAA since 2006. As described in the 
supplemental 2014 attainment plan SIP submittal (applying the 
appropriate temporal profile to convert to tons per day), Idaho stated 
these change-outs have led to permanent reductions of 0.05 tpd direct 
PM2.5, 0.003 tpd NOX, and 0.13 tpd VOC.\11\ These 
woodstove change-out programs achieved permanent and enforceable 
emissions reductions because the RWC ordinances banned the sale or 
installation of non-EPA certified devices in new or existing buildings 
in Franklin County jurisdictions.
---------------------------------------------------------------------------

    \11\ 2014 attainment plan SIP submittal, Section 4.1.
---------------------------------------------------------------------------

    IDEQ also noted that Utah adopted permanent and enforceable control 
measures into its SIP that have reduced PM2.5 and precursor 
emissions and led to the improvement in air quality in the Logan UT-ID 
PM2.5 NAA. IDEQ specifically referenced area source rules 
(2015 reductions of 122 lbs/day NOX, 679 lbs/day 
PM2.5, 3,665 lbs/day VOC) and a vehicle and inspection and 
maintenance program (2015 reductions of 0.214 tons/day for 
NOX and 0.212 tons/day for VOC) in the Utah portion of the 
Logan UT-ID NAA.\12\ IDEQ also referenced Federal measures, including 
the ``Tier 3 Motor Vehicle Emission and Fuel Standards Rule'' (79 FR 
23414), as permanent and enforceable reductions leading to improvement 
in air quality, and ultimately to attainment, in the Logan UT-ID 
PM2.5 NAA.
---------------------------------------------------------------------------

    \12\ See Idaho's September 13, 2019 submittal at Section 5.2.
---------------------------------------------------------------------------

    Based on the foregoing evaluation of these control measures, EPA 
proposes to determine that the improvement in air quality is reasonably 
attributable to permanent and enforceable reductions in emissions 
resulting from implementation of the applicable implementation plan, 
implementation of applicable Federal air pollutant control regulations, 
and other permanent and enforceable reductions.

[[Page 9889]]

D. Fully Approved Maintenance Plan

    CAA section 107(d)(3)(E)(iv) requires that, for a NAA to be 
redesignated to attainment, EPA must fully approve a maintenance plan 
which meets the requirements of CAA section 175A. The plan must 
demonstrate continued attainment of the relevant NAAQS in the area for 
at least 10 years after our approval of the redesignation. Eight years 
after our approval of a redesignation, the State must submit a revised 
maintenance plan demonstrating attainment for the 10 years following 
the initial 10-year period. The maintenance plan must also contain a 
contingency plan to ensure prompt correction of any violation of the 
NAAQS. See CAA sections 175A(b) and (d). The Calcagni Memo provides 
additional guidance on the content of a maintenance plan, stating that 
a maintenance plan should include the following elements: (1) An 
attainment emissions inventory; (2) a maintenance demonstration showing 
attainment for 10 years following redesignation; (3) a commitment to 
maintain the existing monitoring network; (4) verification of continued 
attainment; and (5) a contingency plan to prevent or correct future 
violations of the NAAQS. The following paragraphs describe how each of 
these elements is addressed in Idaho's maintenance plan.
1. Attainment Inventory
    As discussed in the General Preamble (see 57 FR 13498, April 16, 
1992) and the Calcagni Memo, PM2.5 maintenance plans should 
include an attainment emission inventory to identify the level of 
emissions in the area which is sufficient to maintain the NAAQS.
    The maintenance plan attainment year inventory should include the 
emissions during the time period associated with the monitoring data 
showing attainment.\13\ For the Logan, UT-ID PM2.5 NAA, IDEQ 
determined attainment using air quality data from 2015, 2016, and 2017, 
the design value period relied upon for the EPA's Determination of 
Attainment (83 FR 52983, October 19, 2018). The State therefore used 
2017 to calculate its base year attainment inventory, which aligned 
with the 2017 National Emissions Inventory (NEI) data available for 
point, area, on-road mobile, and nonroad mobile sources. IDEQ then 
projected the 2017 base year inventory to both a ``horizon year'' (a 
future year at least 10 years from the approval date of the maintenance 
plan) of 2031 and an interim year of 2026.
---------------------------------------------------------------------------

    \13\ See Calcagni Memo at 8.
---------------------------------------------------------------------------

    The NEI is compiled at the county level, so the State first 
calculated the 2017 emissions inventories for Franklin County, and then 
apportioned these county-wide inventories to the portion of Franklin 
County included in the Logan, UT-ID NAA.\14\ IDEQ projected mobile 
source emissions using the latest version of EPA's Motor Vehicle 
Emissions Simulator (MOVES) model (MOVES2014b). IDEQ used apportioned 
2017 NEI data for the on-road mobile source emissions, and used 
MOVES2014b model defaults for the nonroad portion of the model, because 
the State has not yet developed input files for that version of the 
model.\15\ To best represent emissions that occur on days when the 
ambient concentrations of PM2.5 are of concern, the MOVES 
meteorological inputs were based on an average episodic day 
representing conditions present during wintertime stagnation events 
leading to high levels of ambient PM2.5 in the Logan UT-ID 
PM2.5 NAA.\16\ IDEQ ran MOVES2014b to calculate on-road and 
nonroad mobile source emissions on an average episodic winter day for 
Franklin County for January 2017, 2026 and 2031. Area source emissions 
were apportioned from 2017 NEI data for individual categories, which 
were projected for the 2026 and 2031 inventories based on an average 
annual growth rate. No point sources were listed in the base year or 
projected future inventories. More detailed descriptions of the 2017 
base year inventory and the 2026 and 2031 projected inventories can be 
found in section 4 and Appendix A of Idaho's September 13, 2019 
submittal, in the docket for this action.
---------------------------------------------------------------------------

    \14\ See Appendix A of Idaho's September 13, 2019 submittal for 
the apportionment methodology.
    \15\ With the exception of paved road dust emissions, which IDEQ 
calculated using AP-42 guidance.
    \16\ An episodic day was defined as any day from November 
through March during which the daily average PM2.5 
concentration in Franklin County was above 35 [mu]g/m3. A total of 
62 days were identified that met these criteria at the Logan-Cache 
Airport weather station from 2013 through 2017. The hourly 
meteorological data from these 62 days were then averaged to create 
the final average episodic day inputs.
---------------------------------------------------------------------------

    For each of these source categories, the pollutants that were 
inventoried include: PM2.5, sulfur dioxide (SO2), 
NOX, VOC, and ammonia (NH3). Summary of emission 
figures from 2017 base year and the projected inventories are provided 
in Table 3 of this document.

               Table 3--Idaho Portion of the Logan, UT-ID PM2.5 NAA; Actual Emissions From 2017 and Projected Emissions for 2026 and 2031
                                                        [Pounds per average episodic winter day]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               PM2.5        PM2.5
                   Year                            Source category          condensable   filterable      NOX          SO2          VOC          NH3
--------------------------------------------------------------------------------------------------------------------------------------------------------
2017......................................  Area.........................          9.72        208.8        338.8         28.3      1,626.5        868.6
2017......................................  Mobile.......................  ............        127.3        957.7          1.9        901.2         13.8
2017......................................  Nonroad......................  ............         42.5        286.6          0.8      1,189.1          0.7
                                                                          ------------------------------------------------------------------------------
2017......................................     Total.....................          9.72        378.5        1,583           31      3,716.8        883.1
2026......................................  Area.........................          9.88        222.4        363.5         28.6      2,061.1        872.1
2026......................................  Mobile.......................  ............        109.4        421.8          2.0        533.1         12.5
2026......................................  Nonroad......................  ............         31.2        302.8          0.8        776.4          0.7
                                                                          ------------------------------------------------------------------------------
2026......................................     Total.....................          9.88          363       1088.1         31.4      3,370.6        885.3
2031......................................  Area.........................          9.97          230        377.2         28.8      2,302.6          874
2031......................................  Mobile.......................  ............        110.5        297.3            2        396.3         13.2
2031......................................  Nonroad......................  ............         29.8        306.7          0.8        732.5          0.7
                                                                          ------------------------------------------------------------------------------
2031......................................     Total.....................          9.97        370.4        981.2         31.6      3,431.4        887.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
    Projected change (%)..................  .............................           2.5         -2.2          -38            2        -7.70          0.5
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 9890]]

    Following our review, we have determined that IDEQ prepared an 
adequate attainment inventory for the Idaho portion of the Logan, UT-ID 
PM2.5 NAA.
    In the September 13, 2019 submission, Idaho also provided inventory 
information for the Utah portion of the Logan, UT-ID NAA. Idaho derived 
this inventory from the Utah Division of Air Quality (Utah DAQ), which 
performed a photochemical grid modeling analysis using the 
``Comprehensive Air Quality Model with Extensions'' (v. 6.3, http://www.camx.com/) modeling system for the nonattainment area for Utah's 
attainment, interim, and projected years. Utah used linear projections 
to estimate future years to 2035. Utah DAQ's modeling domain included 
all three of the nonattainment areas in UT and extended into southern 
Idaho to include the Idaho portion of the Logan UT-ID PM2.5 
NAA. The methodology for the mobile, nonroad and area source emissions 
inventories can be found in the Utah DAQ PM2.5 Emissions 
Inventory Preparation Plan (Utah DAQ 2019), in the docket for this 
action. IDEQ interpolated the Utah DAQ projections to 2031 using the 
average annual growth rate for area, mobile, and nonroad sources to 
match the 2031 horizon year for Idaho's redesignation request. The 
actual and projected emissions in the Utah portion of the Logan UT-ID 
PM2.5 NAA are provided in Table 4 of this document. Table 5 
of this document provides Idaho's projected emissions inventories for 
the entire Logan UT-ID PM2.5 NAA, which is the combination 
of the values in Tables 3 and 4 of this document.

                Table 4--Utah Portion of the Logan, UT-ID PM2.5 NAA; Actual Emissions From 2017 and Projected Emissions for 2026 and 2031
                                                        [Pounds per average episodic winter day].
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               PM2.5        PM2.5
                   Year                            Source category          condensable   filterable      NOX          SO2          VOC          NH3
--------------------------------------------------------------------------------------------------------------------------------------------------------
2017......................................  Area.........................          1.83     1,198.17        1,840           60        7,600       26,960
2017......................................  Mobile.......................  ............          460        7,520           40        4,920          200
2017......................................  Nonroad......................  ............          200        1,580  ...........        4,380  ...........
                                                                          ------------------------------------------------------------------------------
2017......................................     Total.....................          1.83     1,858.17       10,940          100       16,900       27,160
2026......................................  Area.........................          2.09     1,277.91        1,400           60        7,760       26,540
2026......................................  Mobile.......................  ............          260        3,040           20        2,780          180
2026......................................  Nonroad......................  ............          120        1,180  ...........        2,540  ...........
                                                                          ------------------------------------------------------------------------------
2026......................................     Total.....................          2.09     1,657.91        5,620           80       13,080       26,720
2031......................................  Area.........................          2.29     1,311.04     1,411.11           60     8,215.56    26,362.22
2031......................................  Mobile.......................  ............       326.67     3,306.67           20     3,357.78       191.11
2031......................................  Nonroad......................  ............       108.89     1,157.78  ...........     2,284.44  ...........
                                                                          ------------------------------------------------------------------------------
2031......................................     Total.....................          2.29      1,746.6     5,875.56           80    13,857.78    26,553.33
--------------------------------------------------------------------------------------------------------------------------------------------------------
    Projected change (%)..................  .............................          25.2         -6.0        -46.3          -20        -18.0        -0.02
--------------------------------------------------------------------------------------------------------------------------------------------------------

                      Table 5--Entire Logan, UT-ID PM2.5 NAA; Actual Emissions From 2017 and Projected Emissions for 2026 and 2031
                                                                 [Pounds per winter day]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               PM2.5        PM2.5
                   Year                            Source category          condensable   filterable      NOX          SO2          VOC          NH3
--------------------------------------------------------------------------------------------------------------------------------------------------------
2017......................................  Area.........................         11.55     1,406.94     2,178.76        88.27     9,226.45    27,828.63
2017......................................  Mobile.......................  ............        587.3      8,477.7        41.94     5,821.24       213.76
2017......................................  Nonroad......................  ............       242.48     1,866.57         0.76     5,569.08         0.66
                                                                          ------------------------------------------------------------------------------
2017......................................     Total.....................         11.55     2,236.72    12,523.03       130.97    20,616.77    28,043.05
2026......................................  Area.........................         11.98     1,500.33     1,763.48        88.58     9,821.12    27,412.08
2026......................................  Mobile.......................  ............       369.36     3,461.84           22     3,313.12       192.55
2026......................................  Nonroad......................  ............       151.19     1,482.79         0.77      3,316.4         0.66
                                                                          ------------------------------------------------------------------------------
2026......................................     Total.....................         11.98     2,020.88     6,708.11       111.35    16,450.64    27,605.29
2031......................................  Area.........................         12.26     1,541.06     1,788.33        88.75    10,518.17    27,236.22
2031......................................  Mobile.......................  ............       437.21     3,603.94        22.05     3,754.04       204.32
2031......................................  Nonroad......................  ............       138.73     1,464.52          .78     3,016.94         0.67
                                                                          ------------------------------------------------------------------------------
2031......................................     Total.....................         12.26        2,117     6,856.79       111.58    17,289.15    27,441.21
--------------------------------------------------------------------------------------------------------------------------------------------------------
    Projected change (%)..................  .............................           6.1         -5.4        -45.2        -14.8        -16.1         -2.1
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based our review of the emissions inventories Idaho provided in its 
September 13, 2019 submittal, shown in Tables 3 through 5 of this 
document, we propose to find that Idaho prepared an adequate attainment 
inventory for the Logan, UT-ID PM2.5 NAA.\17\
---------------------------------------------------------------------------

    \17\ ``Emissions Inventory Guidance for Implementation of Ozone 
and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' May 2017.

---------------------------------------------------------------------------

[[Page 9891]]

2. Maintenance Demonstration
    CAA section 175A requires a state seeking redesignation to 
attainment to submit a SIP revision to provide for the maintenance of 
the NAAQS in the area ``for at least 10 years after the 
redesignation.'' A state can make this demonstration by either showing 
that future emissions of a pollutant or its precursors will not exceed 
the level of the attainment inventory, or by modeling to show that the 
future mix of sources and emissions rates will not cause a violation of 
the NAAQS. See Calcagni Memo, pages 9-10. Idaho elected to demonstrate 
maintenance of the 2006 PM2.5 NAAQS for at least ten years 
following redesignation using the attainment inventory method.
    IDEQ developed projected inventories, provided in Tables 3 through 
5 of this document, to show that the Logan UT-ID area will remain in 
attainment through the year 2031. These projected inventories, covering 
an interim year of 2026 and a horizon year of 2031, show that future 
emissions of NOX, SO2, VOCs, ammonia, and direct 
PM2.5 throughout the NAA will remain at or below the 2017 
attainment-level emissions for the 2006 24-hour PM2.5 NAAQS. 
As these inventories show, emissions from NOX, 
SO2, VOCs and NH3 are projected to decrease 
between 2017 and 2031 (Table 5 of this document). The emissions of 
direct filterable PM2.5 are projected to decline by 5.4% by 
2031 (Table 5 of this document).
    Although emissions from condensable PM2.5 increase by 
6.1% by 2031, Idaho adequately demonstrated that this increase will not 
prevent maintenance of the NAAQS through 2031. The condensable fraction 
of PM2.5 is 0.6% of the total PM2.5-Primary 
levels projected for 2031. As depicted in Table 5 of this document, the 
total condensable PM2.5 emissions are projected to increase 
by 0.71 pounds per winter day between 2017 and 2031, while total 
filterable PM2.5 emissions are projected to decrease by 
119.72 pounds per winter day over the same time period. Overall, total 
PM2.5 (sum of filterable and condensable PM2.5) 
is projected to decrease by 5.3% from 2017 to 2031.
    EPA has reviewed the documentation provided by Idaho for developing 
the 2026 and 2031 emissions inventories for the Logan UT-ID 
PM2.5 NAA. Based on our review, EPA finds that the emissions 
inventories were prepared in accordance with EPA requirements. These 
inventories indicate a decrease in PM2.5 and precursor 
emissions throughout the maintenance period, therefore EPA is proposing 
to determine that the projected emissions inventories in the Idaho 
maintenance plan sufficiently demonstrate that the Logan UT-ID 
PM2.5 NAA will continue to maintain the 2006 24-hour 
PM2.5 standard throughout the maintenance period.
3. Monitoring Network
    Once a NAA has been redesignated to attainment, the state must 
continue to operate an appropriate air quality monitoring network, in 
accordance with 40 CFR part 58, to verify the attainment status of the 
area.\18\ The maintenance plan should contain provisions for continued 
operation of air quality monitors that will provide such verification. 
In the maintenance plan, IDEQ noted that it currently operates a 
regulatory monitor (the Preston monitor) in the Idaho portion of the 
Logan, UT-ID PM2.5 NAA, and committed to continue operating 
a regulatory monitoring network in Franklin County in order to verify 
continued attainment of the PM2.5 NAAQS and track the 
progress of the maintenance plan. IDEQ also stated that it will work 
with EPA each year through the air monitoring network review process 
(per 40 CFR part 58) to determine the adequacy of the monitoring 
network.\19\ EPA proposes to determine that the maintenance plan 
contains adequate provisions for continued operation of an air quality 
monitoring network to verify maintenance of the 2006 PM2.5 
NAAQS.
---------------------------------------------------------------------------

    \18\ As stated, Utah and Idaho signed an MOU to collectively 
meet the monitoring requirements of 40 CFR part 58, Appendix D in 
the Logan UT-ID MSA on September 1, 2020.
    \19\ See EPA's November 9, 2020 approval of Idaho's 2020 Annual 
Monitoring Network Plan, in the docket for this action.
---------------------------------------------------------------------------

4. Verification of Continued Attainment
    As stated in Section III.D.3 of this document, in its maintenance 
plan, Idaho commits to continue to operate a regulatory monitoring 
network in order to verify continued attainment of the PM2.5 
NAAQS in the Idaho portion of the Logan UT-ID area. Idaho is also 
required to periodically update the emissions inventory for Franklin 
County in accordance with the Annual Air Emissions Reporting 
Requirements Rule (AERR) during the maintenance plan period. This 
includes developing annual inventories for major point sources and a 
comprehensive periodic inventory covering all source categories every 
three years.
5. Contingency Plan
    CAA section 175A(d) requires that a maintenance plan also include 
contingency provisions, as necessary, to promptly correct any violation 
of the NAAQS that occurs after redesignation of the area to attainment. 
For the purposes of CAA section 175A, a state is not required to have 
fully adopted contingency measures that will take effect without 
further action by the state in order for the maintenance plan to be 
approved. However, the contingency plan is an enforceable part of the 
SIP and should ensure that contingency measures are adopted 
expeditiously once they are triggered. The plan should discuss the 
measures to be adopted and a schedule and procedure for adoption and 
implementation. The contingency plan must require that the state will 
implement all measures contained in the Part D nonattainment plan for 
the area prior to redesignation. The state should also identify the 
specific indicators, or triggers, which will be used to determine when 
the contingency plan will be implemented.
    Idaho's maintenance plan outlines the procedures for the adoption 
and implementation of contingency measures to further reduce emissions 
should a violation occur. Idaho's contingency measures include a 
warning level response and an action level response. An initial warning 
level response is triggered for the 2006 24-hour PM2.5 NAAQS 
when the 98th percentile 24-hour PM2.5 concentration for a 
single calendar year reaches 35.5 [micro]g/m\3\ or greater within the 
area. An action level response will be prompted by any one of the 
following: (1) A two year average of the 98th percentile reaches 35.5 
[micro]g/m\3\ or greater within the area; or (2) a violation of the 
standard occurs in the area (i.e. a three-year average of the 98th 
percentile reaches 35.5 [micro]g/m\3\ or greater).
    Regardless of which level of response is triggered, the State will 
evaluate all appropriate data including air quality data, evaluation of 
wood smoke programs and information on wildfires or winter power 
outages to determine the cause of the exceedance. IDEQ will perform 
this evaluation within six months of the end of the year in which the 
NAAQS is exceeded or violated. Should a warning level response be 
triggered, and IDEQ determines that additional emissions reductions are 
necessary, the State will adopt and implement contingency measures as 
expeditiously as possible and no later than 18 months from the 
determination of a single year exceedance based on quality assured 
data. Should an action

[[Page 9892]]

level response be triggered, implementation of necessary control 
measures will take place as expeditiously as possible, but in no event 
later than 18 months after IDEQ determines, based on quality-assured 
ambient data, that an action level trigger has been exceeded.
    Idaho has identified the following potential contingency measures 
for the maintenance plan:
     Measures to address emissions from residential wood 
combustion, including the potential implementation of a burn ban in the 
maintenance area at a lower threshold than currently in place in the 
ordinances for the six cities in the Idaho portion of the Logan UT-ID 
PM2.5 NAA. The current ordinances trigger a burn ban when 
the Air Quality Index (AQI) level reaches 75.
     Additional measures to address other PM2.5 
sources identified in the emissions inventory such as on-road and 
nonroad vehicles, industrial sources, and dust.
    Based on our analysis of Idaho's submittal, we propose to find that 
the contingency measure provisions provided in Idaho's Logan, UT-ID 
PM2.5 maintenance plan are sufficient and meet the 
requirements of CAA section 175A(d).

E. Requirements for Transportation Conformity and Motor Vehicle 
Emissions Budgets (MVEBs).

    Transportation conformity is required by CAA section 176(c). EPA's 
conformity rule at 40 CFR part 93, subpart A requires that 
transportation plans, programs, and projects conform to SIPs and 
establishes the criteria and procedures for determining whether or not 
they conform. Conformity to a SIP means that transportation activities 
will not produce new air quality violations, worsen existing 
violations, or delay timely attainment of the NAAQS. Thus, EPA's 
conformity rule requires a demonstration that emissions from a 
Metropolitan Planning Organization's (MPO's) Regional Transportation 
Plan and Transportation Improvement Program, involving Federal Highway 
Administration (FHWA) or Federal Transit Administration (FTA) funding 
or approval, are consistent with the MVEB(s) contained in a control 
strategy SIP revision or maintenance plan (40 CFR 93.101, 93.118, and 
93.124). A MVEB is the level of mobile source emissions of a pollutant 
relied upon in the attainment or maintenance demonstration to attain or 
maintain compliance with the NAAQS in the nonattainment or maintenance 
area.
    A PM2.5 maintenance plan should identify MVEBs for 
direct PM2.5, NOX and all other PM2.5 
precursors from on-road mobile source emissions that are determined to 
significantly contribute to PM2.5 levels in the area.\20\ To 
determine which precursor pollutants are required to have an MVEB, IDEQ 
reviewed PM2.5 speciation at the Franklin monitor. Based on 
PM2.5 speciation data and the local emissions inventory 
composition for each pollutant, IDEQ determined that in addition to 
NOX and direct PM2.5, the maintenance plan should 
also include an MVEB for VOCs because they are important precursors to 
secondary formation PM2.5. The State excluded direct 
PM2.5 emissions from paved road dust from the MVEBs in 
accordance with 40 CFR 93.102(b)(3), as these emissions made up only 1% 
of total wintertime contributions at the Franklin monitor. Vehicle 
emissions of SO2 and NH3 were also found to 
contribute minimally to PM2.5 in the area and therefore the 
maintenance plan does not include MVEBs for these precursors in 
accordance with 40 CFR 93.102(b)(2)(v). See Section 6 of Idaho's 
maintenance plan, in the docket for this action, for further analysis 
of the pollutants and precursors and the decisions on whether or not 
MVEBs were required for the individual pollutants and precursors.
---------------------------------------------------------------------------

    \20\ See 40 CFR 93.102(b)(2)(iv)-(v) and (b)(3).
---------------------------------------------------------------------------

    The MVEBs for 2031 are identical to the on-road mobile source 
emissions inventory provided for direct PM2.5, 
NOX and VOCs in Table 1 (in Section II.D.1 of this document) 
of this proposed action for that year, except that the 2031 direct 
PM2.5 budget does not include paved road dust. As stated in 
that section, IDEQ used EPA's MOVES2014b model to develop vehicle 
emissions estimates for 2031, which were recalculated into tons per day 
(from lbs per day) for the 2031 MVEBs.
    Based on its analysis, IDEQ set the mobile source emissions budgets 
for 2031 provided in Table 6 of this proposed action, as part of the 
September 13, 2019 maintenance plan submission. The previously approved 
2017 MVEBs (see 85 FR 9664, February 20, 2020), are included in Table 
6. According to EPA's conformity rule, the emissions budget acts as a 
ceiling on emissions in the year for which it is defined or until a SIP 
revision modifies the budget.\21\
---------------------------------------------------------------------------

    \21\ See 40 CFR 93.118.

                 Table 6--2017 and 2031 MVEBs for the Idaho Portion of the Logan UT-ID PM2.5 NAA
----------------------------------------------------------------------------------------------------------------
                                                                       Motor vehicle emissions budget (tpd)
                                                                 -----------------------------------------------
                              Year                                 Direct PM2.5
                                                                                        NOX             VOC
----------------------------------------------------------------------------------------------------------------
2017............................................................            .029            .544            .467
2031............................................................            .009            .149            .198
----------------------------------------------------------------------------------------------------------------

    We propose to find that Idaho has evaluated the appropriate 
pollutants and precursors and appropriately established MVEBs for 
direct PM2.5, NOX and VOCs. Idaho used the most 
up-to-date model (MOVES2014b) available at the time of submission in 
order to appropriately calculate these budgets.\22\ The MVEBs are based 
on the control measures in the maintenance plan and consistent with 
maintaining the 2006 24-hour PM2.5 NAAQS. Based on our 
review of Idaho's 2031 MVEBs, we are proposing to approve the budgets.
---------------------------------------------------------------------------

    \22\ See document titled ``EPA R10 MVEB and MOVES TSD'' in the 
docket for this proposed action (EPA-R10-OAR-2020-0190) on 
www.regulations.gov.
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IV. Proposed Action

    EPA is proposing to redesignate the Idaho portion of the Logan UT-
ID PM2.5 NAA, and proposing to approve the associated 
maintenance plan for the area. If this proposal is finalized, the 
designation status of the Idaho portion of the Logan, UT-ID 
PM2.5 NAA under 40 CFR part 81 will be revised to attainment 
upon the effective date of that final action.

V. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan under section

[[Page 9893]]

107(d)(3)(E) are actions that affect the status of a geographical area 
and do not impose any additional regulatory requirements on sources 
beyond those imposed by state law. A 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 CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 
CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to 
approve state choices, provided that they meet the criteria of the CAA. 
Accordingly, this action merely approves state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
already imposed by state law. For that reason, 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);
     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 CAA; and
     Does not provide 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 SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, this rule does not have tribal implications as specified by 
Executive Order 13175 (65 FR 67249, November 9, 2000), because 
redesignation is an action that affects the status of a geographical 
area and does not impose any new regulatory requirements on tribes, 
impact any existing sources of air pollution on tribal lands, nor 
impair the maintenance of ozone national ambient air quality standards 
in tribal lands.

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Lead, Nitrogen dioxide, Ozone, 
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: February 9, 2021.
Michelle L. Pirzadeh,
Acting Regional Administrator, Region 10.
[FR Doc. 2021-03031 Filed 2-16-21; 8:45 am]
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