Document ID: EPA-R10-OAR-2018-0824-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Idaho; 2015 Ozone NAAQS Interstate Transport Requirements
Posted Date: 2020-01-23T05:00Z

[Federal Register Volume 85, Number 15 (Thursday, January 23, 2020)]
[Proposed Rules]
[Pages 3874-3879]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-00888]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R10-OAR-2018-0824; FRL-10004-49-Region 10]

Air Plan Approval; ID; 2015 Ozone NAAQS Interstate Transport 
Requirements

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Clean Air Act (CAA or the Act) requires each State 
Implementation Plan (SIP) to contain adequate provisions prohibiting 
emissions that will have certain adverse air quality effects in other 
states. On September 26, 2018, the State of Idaho made a submission to 
the Environmental Protection Agency (EPA) to address these requirements 
for the 2015 ozone National Ambient Air Quality Standards (NAAQS). The 
EPA is proposing to approve the submission as meeting the requirement 
that each SIP contain adequate provisions to prohibit emissions that 
will significantly contribute to nonattainment or interfere with 
maintenance of the 2015 ozone NAAQS in any other state.

DATES: Written comments must be received on or before February 24, 
2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2018-0824 at https://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. The EPA may publish any 
comment received to its public docket. Do not 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. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e. on the web, cloud, or other 
file sharing system). For additional submission methods, 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: Claudia Vaupel at (206) 553-6121, or 
vaupel.claudia@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, it is intended to refer to the EPA. This 
supplementary information section is arranged as follows:

Table of Contents

I. Background
II. State Submission
III. EPA Evaluation
IV. Proposed Action
V. Statutory and Executive Order Reviews

I. Background

    On October 1, 2015, the EPA promulgated a revision to the ozone 
NAAQS (2015 ozone NAAQS), lowering the level of both the primary and 
secondary standards to 0.070 parts per million (ppm).\1\ Section 
110(a)(1) of the CAA requires states to submit, within 3 years after 
promulgation of a new or revised standard, SIPs meeting the applicable 
requirements of section 110(a)(2).\2\ One of these applicable 
requirements is found in section 110(a)(2)(D)(i), otherwise known as 
the good neighbor provision, which generally requires SIPs to contain 
adequate provisions to prohibit in-state emissions activities from 
having certain adverse air quality effects on other states due to 
interstate transport of pollution. There are four so-called ``prongs'' 
within CAA section 110(a)(2)(D)(i): Section 110(a)(2)(D)(i)(I) contains 
prongs 1 and 2, while section 110(a)(2)(D)(i)(II) includes prongs 3 and 
4. This action addresses the first two prongs under section 
110(a)(2)(D)(i)(I). Under prongs 1 and 2 of the good neighbor 
provision, a SIP for a new or revised NAAQS must contain adequate 
provisions prohibiting any source or other type of emissions activity 
within

[[Page 3875]]

the state from emitting air pollutants in amounts that will 
significantly contribute to nonattainment of the NAAQS in another state 
(prong 1) or from interfering with maintenance of the NAAQS in another 
state (prong 2). Under section 110(a)(2)(D)(i)(I) of the CAA, the EPA 
and states must give independent significance to prong 1 and prong 2 
when evaluating downwind air quality problems under section 
110(a)(2)(D)(i)(I).\3\
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    \1\ National Ambient Air Quality Standards for Ozone, Final 
Rule, 80 FR 65292 (October 26, 2015). Although the level of the 
standard is specified in the units of ppm, ozone concentrations are 
also described in parts per billion (ppb). For example, 0.070 ppm is 
equivalent to 70 ppb.
    \2\ SIP revisions that are intended to meet the applicable 
requirements of section 110(a)(1) and (2) of the CAA are often 
referred to as infrastructure SIPs and the applicable elements under 
110(a)(2) are referred to as infrastructure requirements.
    \3\ See North Carolina v. EPA, 531 F.3d 896, 909-911 (2008).
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    We note that the EPA has addressed the interstate transport 
requirements of CAA section 110(a)(2)(D)(i)(I) with respect to prior 
ozone NAAQS in several regional regulatory actions, including the 
Cross-State Air Pollution Rule (CSAPR), which addressed interstate 
transport with respect to the 1997 ozone NAAQS as well as the 1997 and 
2006 fine particulate matter standards, and the Cross-State Air 
Pollution Rule Update for the 2008 ozone NAAQS (CSAPR Update).\4\ These 
actions only addressed interstate transport in the eastern United 
States \5\ and did not address the 2015 ozone NAAQS.
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    \4\ See 76 FR 48208 (August 8, 2011) (i.e., CSAPR) and 81 FR 
74504 (October 26, 2016) (i.e., CSAPR Update).
    \5\ For purposes of CSAPR and the CSAPR Update action, the 
Western U.S. (or the West) was considered to consist of the 11 
western contiguous states of Arizona, California, Colorado, Idaho, 
Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. 
The Eastern U.S. (or the East) was considered to consist of the 37 
states east of the 11 Western states.
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    Through the development and implementation of CSAPR, the CSAPR 
Update and previous regional rulemakings pursuant to the good neighbor 
provision,\6\ the EPA, working in partnership with states, developed 
the following four-step interstate transport framework to address the 
requirements of the good neighbor provision for the ozone NAAQS: \7\ 
(1) Identify downwind air quality problems; (2) identify upwind states 
that impact those downwind air quality problems sufficiently such that 
they are considered ``linked'' and therefore warrant further review and 
analysis; (3) identify the emissions reductions necessary (if any), 
considering cost and air quality factors, to prevent linked upwind 
states identified in step 2 from contributing significantly to 
nonattainment or interfering with maintenance of the NAAQS at the 
locations of the downwind air quality problems; and (4) adopt permanent 
and enforceable measures needed to achieve those emissions reductions.
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    \6\ Other regional rulemakings addressing ozone transport 
include the NOX SIP Call, 63 FR 57356 (October 27, 1998), 
and the Clean Air Interstate Rule (CAIR), 70 FR 25162 (May 12, 
2005).
    \7\ The four-step interstate framework has also been used to 
address requirements of the good neighbor provision for some 
previous particulate matter and ozone NAAQS, including in the 
Western United States. See, e.g., 83 FR 30380 (June 28, 2018) and 83 
FR 5375, 5376-77 (February 7, 2018).
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    The EPA has released several documents containing information 
relevant to evaluating interstate transport with respect to the 2015 
ozone NAAQS. First, on January 6, 2017, the EPA published a notice of 
data availability (NODA) with preliminary interstate ozone transport 
modeling with projected ozone design values for 2023, on which we 
requested comment.\8\ The year 2023 was used as the analytic year for 
this preliminary modeling because that year aligns with the expected 
attainment year for Moderate ozone nonattainment areas.\9\ On October 
27, 2017, we released a memorandum (2017 memorandum) containing updated 
modeling data for 2023, which incorporated changes made in response to 
comments on the NODA.\10\ Although the 2017 memorandum also released 
data for a 2023 modeling year, we specifically stated that the modeling 
may be useful for states developing SIPs to address remaining good 
neighbor obligations for the 2008 ozone NAAQS but did not address the 
2015 ozone NAAQS. And, on March 27, 2018, we issued a memorandum (March 
2018 memorandum) indicating the same 2023 modeling data released in the 
2017 memorandum would also be useful for evaluating potential downwind 
air quality problems with respect to the 2015 ozone NAAQS (step 1 of 
the four-step framework).
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    \8\ See Notice of Availability of the Environmental Protection 
Agency's Preliminary Interstate Ozone Transport Modeling Data for 
the 2015 Ozone National Ambient Air Quality Standard (NAAQS), 82 FR 
1733 (January 6, 2017).
    \9\ 82 FR 1735 (January 6, 2017).
    \10\ See Information on the Interstate Transport State 
Implementation Plan Submissions for the 2008 Ozone National Ambient 
Air Quality Standards under Clean Air Act Section 
110(a)(2)(D)(i)(I), October 27, 2017, available in the docket for 
this action or at https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
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    The March 2018 memorandum included newly available contribution 
modeling results to assist states in evaluating their impact on 
potential downwind air quality problems (step 2 of the four-step 
framework) in their efforts to develop good neighbor SIPs for the 2015 
ozone NAAQS to address their interstate transport obligations.\11\ The 
EPA subsequently issued two more memoranda in August and October 2018, 
providing guidance to states developing good neighbor SIPs for the 2015 
ozone NAAQS concerning, respectively, potential contribution thresholds 
that may be appropriate to apply in step 2 and considerations for 
identifying downwind areas that may have problems maintaining the 
standard (under prong 2 of the good neighbor provision) at step 1 of 
the framework.\12\
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    \11\ See Information on the Interstate Transport State 
Implementation Plan Submissions for the 2015 Ozone National Ambient 
Air Quality Standards under Clean Air Act Section 
110(a)(2)(D)(i)(I), March 27, 2018, available in the docket for this 
action or at https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
    \12\ See Analysis of Contribution Thresholds for Use in Clean 
Air Act Section 110(a)(2)(D)(i)(I) Interstate Transport State 
Implementation Plan Submissions for the 2015 Ozone National Ambient 
Air Quality Standards, August 31, 2018 (``August 2018 memorandum''), 
and Considerations for Identifying Maintenance Receptors for Use in 
Clean Air Act Section 110(a)(2)(D)(i)(I) Interstate Transport State 
Implementation Plan Submissions for the 2015 Ozone National Ambient 
Air Quality Standards, October 19, 2018, available in the docket for 
this action or at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
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    The March 2018 memorandum describes the process and results of the 
updated photochemical and source-apportionment modeling used to project 
ambient ozone concentrations for the year 2023 and the state-by-state 
impacts on those concentrations. The March 2018 memorandum also 
explains that the selection of the 2023 analytic year aligns with the 
2015 ozone NAAQS attainment year for Moderate nonattainment areas. As 
described in more detail in the 2017 and March 2018 memoranda, the EPA 
used the Comprehensive Air Quality Model with Extensions (CAMx version 
6.40) to model average and maximum design values in 2023 to identify 
potential nonattainment and maintenance receptors (i.e., monitoring 
sites that are projected to have problems attaining or maintaining the 
2015 ozone NAAQS). The March 2018 memorandum presents design values 
calculated in two ways: First, following the EPA's historic ``3 x 3'' 
approach \13\ to evaluating all sites, and second, following a modified 
approach for coastal monitoring sites in which ``overwater'' modeling 
data were not included in the calculation of future year design values 
(referred to as the ``no water'' approach).
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    \13\ See March 2018 memorandum, p. 4
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    For purposes of identifying potential nonattainment and maintenance 
receptors in 2023, the EPA applied the same approach used in the CSAPR 
Update, wherein the EPA considered a combination of monitoring data and 
modeling projections to identify

[[Page 3876]]

monitoring sites that are projected to have problems attaining or 
maintaining the NAAQS. Specifically, the EPA identified nonattainment 
receptors as those monitoring sites with measured values \14\ exceeding 
the NAAQS that also have projected (i.e., in 2023) average design 
values exceeding the NAAQS. The EPA identified maintenance receptors as 
those monitoring sites with projected maximum design values exceeding 
the NAAQS. This included sites with measured values below the NAAQS but 
with projected average and maximum design values exceeding the NAAQS, 
and monitoring sites with projected average design values below the 
NAAQS but with projected maximum design values exceeding the NAAQS. The 
EPA included the design values and monitoring data for all monitoring 
sites projected to be potential nonattainment or maintenance receptors 
based on the updated 2023 modeling in Attachment B to the March 2018 
memorandum.
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    \14\ The EPA used 2016 ozone design values, based on 2014-2016 
measured data, which were the most current data at the time of the 
analysis. See attachment B of the March 2018 memorandum, p. B-1.
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    After identifying potential downwind nonattainment and maintenance 
receptors, the EPA next performed nationwide, state-level ozone source-
apportionment modeling to estimate the expected impact from each state 
to each nonattainment and maintenance receptor.\15\ The EPA included 
contribution information resulting from the source-apportionment 
modeling in Attachment C to the March 2018 memorandum. For more 
specific information on the modeling and analysis, please see the 2017 
and March 2018 memoranda, the NODA for the preliminary interstate 
transport assessment, and the supporting technical documents included 
in the docket for this action.
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    \15\ As discussed in the March 2018 memorandum, the EPA 
performed source-apportionment model runs for a modeling domain that 
covers the 48 contiguous United States and the District of Columbia, 
and adjacent portions of Canada and Mexico.
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    In the CSAPR and the CSAPR Update, the EPA used a threshold of one 
percent of the NAAQS to determine whether a given upwind state was 
``linked'' at step 2 of the four-step framework and would therefore 
contribute to downwind nonattainment and maintenance sites identified 
in step 1. If a state's impact did not equal or exceed the one percent 
threshold, the upwind state was not ``linked'' to a downwind air 
quality problem, and the EPA therefore concluded the state will not 
significantly contribute to nonattainment or interfere with maintenance 
of the NAAQS in the downwind states. However, if a state's impact 
equaled or exceeded the one percent threshold, the state's emissions 
were further evaluated in step 3, taking into account both air quality 
and cost considerations, to determine what, if any, emissions 
reductions might be necessary to address the good neighbor provision.
    As noted previously, on August 31, 2018, the EPA issued a 
memorandum (the August 2018 memorandum) providing guidance concerning 
potential contribution thresholds that may be appropriate to apply with 
respect to the 2015 ozone NAAQS in step 2. Consistent with the process 
for selecting the one percent threshold in CSAPR and the CSAPR Update, 
the memorandum included analytical information regarding the degree to 
which potential air quality thresholds would capture the collective 
amount of upwind contribution from upwind states to downwind receptors 
for the 2015 ozone NAAQS. The August 2018 memorandum indicated that, 
based on the EPA's analysis of its most recent modeling data, the 
amount of upwind collective contribution captured using a 1 ppb 
threshold is generally comparable, overall, to the amount captured 
using a threshold equivalent to one percent of the 2015 ozone NAAQS. 
Accordingly, the EPA indicated that it may be reasonable and 
appropriate for states to use a 1 ppb contribution threshold, as an 
alternative to the one percent threshold, at step 2 of the four-step 
framework in developing their SIP revisions addressing the good 
neighbor provision for the 2015 ozone NAAQS.\16\
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    \16\ See August 2018 memorandum, p. 4.
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    While the March 2018 memorandum presented information regarding the 
EPA's latest analysis of ozone transport following the approaches the 
EPA has taken in prior regional rulemaking actions, the EPA has not 
made any final determinations regarding how states should identify 
downwind receptors with respect to the 2015 ozone NAAQS at step 1 of 
the four-step framework. Rather, the EPA noted that states have 
flexibility in developing their own SIPs to follow different analytical 
approaches than the EPA's, so long as their chosen approach has an 
adequate technical justification and is consistent with the 
requirements of the CAA.

II. State Submission

    On September 26, 2018, Idaho submitted a SIP revision addressing 
the CAA section 110(a)(2)(D)(i)(I) interstate transport requirements 
for the 2015 ozone NAAQS. Idaho's submission included a review of the 
state's ozone monitoring data and an analysis of ozone precursor 
emissions contributions and trends (nitrogen oxides and volatile 
organic compounds). Idaho's submission also reviewed programs and 
regulations that reduce ozone precursor emissions in the state. Idaho 
relied on the results of EPA's modeling for the 2015 ozone NAAQS, 
contained in the March 2018 memorandum, to identify downwind 
nonattainment and maintenance receptors that may be impacted by 
emissions from sources in Idaho. Based on Idaho's review of EPA's 
methodology, emissions reductions, and modeling assumptions, Idaho 
determined that EPA's future year projections were appropriate for 
purposes of evaluating Idaho's impact on attainment and maintenance of 
the 2015 ozone NAAQS in other states. Thus, Idaho concurred with the 
EPA's photochemical modeling results that indicate Idaho's greatest 
impact on any potential downwind nonattainment or maintenance receptor 
would be 0.19 ppb. Idaho compared these values to a screening threshold 
of 0.70 ppb, representing one percent of the 2015 ozone NAAQS, and 
concluded that because Idaho's impacts to neighboring states are 
projected to be less than 0.70 ppb, emissions from Idaho sources will 
not significantly contribute to nonattainment or interfere with 
maintenance of the 2015 ozone NAAQS in any other state.
    Idaho also evaluated potential ozone transport to the Fort Hall 
Reservation, located in southeast Idaho. The EPA approved the Shoshone-
Bannock Tribes of the Fort Hall Reservation to be treated as an 
affected downwind state for CAA sections 110(a)(2)(D) and 126. The 
nearest ozone monitor to the Fort Hall Reservation is in Butte County, 
Idaho, in the Idaho Falls area (Site ID 160230101), approximately 85 km 
northeast of the Fort Hall Reservation. Idaho noted that the ozone 
concentrations at the Idaho Falls monitor have been below the 2015 
ozone NAAQS. Idaho's submission also included findings from its 2017 
photochemical modeling study of an 81-day episode during summer 2013, 
with unusually high ozone concentrations throughout Idaho, including 
the Fort Hall Reservation. Idaho concluded that Idaho emissions do not 
contribute significantly to nonattainment or interfere with maintenance 
on the Fort Hall Reservation.

III. EPA Evaluation

    The EPA is proposing to rely on the 2023 modeling data identifying 
downwind receptors and upwind state

[[Page 3877]]

contributions, as released in the March 2018 memorandum, to evaluate 
Idaho's good neighbor obligation with respect to the 2015 ozone NAAQS. 
On September 13, 2019, the D.C. Circuit issued its decision in 
Wisconsin v. EPA addressing legal challenges to the CSAPR Update, in 
which the EPA partially addressed certain upwind states' good neighbor 
obligations for the 2008 ozone NAAQS. 938 F.3d 303. While the court 
generally upheld the rule as to most of the challenges raised in the 
litigation, the court remanded the CSAPR Update to the extent it failed 
to require upwind states to eliminate their significant contributions 
in accordance with the attainment dates found in CAA section 181 by 
which downwind states must come into compliance with the NAAQS. Id. at 
313. In light of the court's decision, the EPA is providing further 
explanation regarding why it proposes to find that it is appropriate 
and consistent with the statute--as well as the legal precedent--to use 
the 2023 analytic year for assessing good neighbor obligations for the 
2015 ozone NAAQS.
    The EPA believes that 2023 is an appropriate year for analysis of 
good neighbor obligations for the 2015 ozone NAAQS because the 2023 
ozone season is the last relevant ozone season during which achieved 
emissions reductions in linked upwind states could assist downwind 
states with meeting the August 2, 2024 Moderate area attainment date 
for the 2015 ozone NAAQS. The EPA recognizes that the attainment date 
for nonattainment areas classified as Marginal for the 2015 ozone NAAQS 
is August 2, 2021, which currently applies in several downwind 
nonattainment areas evaluated in the EPA's modeling.\17\ However, as 
explained below, the EPA does not believe that either the statute or 
applicable case law requires the evaluation of good neighbor 
obligations in a future year aligned with the attainment date for 
nonattainment areas classified as Marginal.
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    \17\ The Marginal area attainment date is not applicable for 
nonattainment areas already classified as Moderate or higher, such 
as the New York Metropolitan Area. For the status of all 
nonattainment areas under the 2015 ozone NAAQS, see U.S. EPA, 8-Hour 
Ozone (2015) Designated Area/State Information, https://www3.epa.gov/airquality/greenbook/jbtc.html (last updated September 
30, 2019).
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    The good neighbor provision instructs the EPA and states to apply 
its requirements ``consistent with the provisions of'' title I of the 
CAA. CAA section 110(a)(2)(D)(i); see also North Carolina v. EPA, 531 
F.3d 896, 911-12 (D.C. Cir. 2008). This consistency instruction follows 
the requirement that plans ``contain adequate provisions prohibiting'' 
certain emissions in the good neighbor provision. As the D.C. Circuit 
held in North Carolina, and more recently in Wisconsin, the good 
neighbor provision must be applied in a manner consistent with the 
designation and planning requirements in title I that apply in downwind 
states and, in particular, the timeframe within which downwind states 
are required to implement specific emissions control measures in 
nonattainment areas and submit plans demonstrating how those areas will 
attain, relative to the applicable attainment dates. See North 
Carolina, 896 F.3d at 912 (holding that the good neighbor provision's 
reference to title I requires consideration of both procedural and 
substantive provisions in title I); Wisconsin, 938 F.3d at 313-18.
    While the EPA recognizes, as the court held in North Carolina and 
Wisconsin, that upwind emissions-reduction obligations therefore must 
generally be aligned with downwind receptors' attainment dates, unique 
features of the statutory requirements associated with the Marginal 
area planning requirements and attainment date under CAA section 182 
lead the EPA to conclude that it is more reasonable and appropriate to 
require the alignment of upwind good neighbor obligations with later 
attainment dates applicable for Moderate or higher classifications. 
Under the Clean Air Act, states with areas designated nonattainment are 
generally required to submit, as part of their SIP, an ``attainment 
demonstration'' that shows, usually through air quality modeling, how 
an area will attain the NAAQS by the applicable attainment date. See 
CAA section 172(c)(1).\18\ Such plans must also include, among other 
things, the adoption of all ``reasonably available'' control measures 
on existing sources, a demonstration of ``reasonable further progress'' 
toward attainment, and contingency measures, which are specific 
controls that will take effect if the area fails to attain by its 
attainment date or fails to make reasonable further progress toward 
attainment. See, e.g., CAA section 172(c)(1); 172(c)(2); 172(c)(9). 
Ozone nonattainment areas classified as Marginal are excepted from 
these general requirements under the CAA--unlike other areas designated 
nonattainment under the Act (including for other NAAQS pollutants), 
Marginal ozone nonattainment areas are specifically exempted from 
submitting an attainment demonstration and are not required to 
implement any specific emissions controls at existing sources in order 
to meet the planning requirements applicable to such areas. See CAA 
section 182(a) (``The requirements of this subsection shall apply in 
lieu of any requirement that the State submit a demonstration that the 
applicable implementation plan provides for attainment of the ozone 
standard by the applicable attainment date in any Marginal Area.'') 
\19\ Marginal ozone nonattainment areas are also exempted from 
demonstrating reasonable further progress towards attainment and 
submitting contingency measures. See CAA section 182(a) (does not 
include a reasonable further progress requirement and specifically 
notes that ``Section [172(c)(9)] of this title (relating to contingency 
measures) shall not apply to Marginal Areas'').
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    \18\ Part D of title I of the Clean Air Act provides the plan 
requirements for all nonattainment areas. Subpart 1, which includes 
section 172(c), applies to all nonattainment areas. Congress 
provided in subparts 2-5 additional requirements specific to the 
various NAAQS pollutants that nonattainment areas must meet.
    \19\ States with Marginal nonattainment areas are required to 
implement new source review permitting for new and modified sources, 
but the purpose of those requirements is to ensure that potential 
emissions increases do not interfere with progress towards 
attainment, as opposed to reducing existing emissions. Moreover, the 
EPA acknowledges that states within ozone transport regions must 
implement certain emission control measures at existing sources in 
accordance with CAA section 184, but those requirements apply 
regardless of the applicable area designation or classification.
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    Existing regulations--either local, state, or federal--are 
typically a part of the reason why ``additional'' local controls are 
not needed to bring Marginal nonattainment areas into attainment. As 
described in the EPA's record for its final rule defining area 
classifications for the 2015 ozone NAAQS and establishing associated 
attainment dates, history has shown that the majority of areas 
classified as Marginal for prior ozone standards attained the 
respective standards by the Marginal area attainment date (i.e., 
without being re-classified to a Moderate designation). 83 FR 10376 
(March 9, 2018). As part of a historical lookback, the EPA calculated 
that by the relevant attainment date for areas classified as Marginal, 
85 percent of such areas attained the 1979 1-hour ozone NAAQS, and 64 
percent attained the 2008 ozone NAAQS. See Response to Comments, 
section A.2.4.\20\ Based on these historical data, the EPA expects that 
many areas classified as Marginal for the 2015 ozone NAAQS will also 
attain by the relevant attainment date as

[[Page 3878]]

a result of emissions reductions that are already expected to occur 
through implementation of existing local, state, and federal emissions 
reduction programs. To the extent states have concerns about meeting 
their attainment date for a Marginal area, the CAA under section 
181(b)(3) provides authority for them to voluntarily request a higher 
classification for individual areas, if needed.
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    \20\ Available at https://www.regulations.gov/document?D=EPA-HQ-OAR-2016-0202-0122.
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    Areas that are classified as Moderate typically have more 
pronounced air quality problems than Marginal areas or have been unable 
to attain the NAAQS under the minimal requirements that apply to 
Marginal areas. See CAA sections 181(a)(1) (classifying areas based on 
the degree of nonattainment relative to the NAAQS) and (b)(2) 
(providing for reclassification to the next highest designation upon 
failure to attain the standard by the attainment date). Thus, unlike 
Marginal areas, the statute explicitly requires a state with an ozone 
nonattainment area classified as Moderate or higher to develop an 
attainment plan demonstrating how the state will address the more 
significant air quality problem, which generally requires the 
application of various control measures to existing sources of 
emissions located in the nonattainment area. See generally CAA sections 
172(c) and 182(b)-(e).
    Given that downwind states are not required to demonstrate 
attainment by the attainment date or impose additional controls on 
existing sources in a Marginal nonattainment area, the EPA believes 
that it would be inconsistent to interpret the good neighbor provision 
as requiring the EPA to evaluate the necessity for upwind state 
emissions reductions based on air quality modeled in a future year 
aligned with the Marginal area attainment date. Rather, the EPA 
believes it is more appropriate and consistent with the nonattainment 
planning provisions in title I to evaluate downwind air quality and 
upwind state contributions, and, therefore, the necessity for upwind 
state emissions reductions, in a year aligned with an area 
classification in connection with which downwind states are also 
required to demonstrate attainment and implement controls on existing 
sources--i.e., with the Moderate area attainment date, rather than the 
Marginal area date. With respect to the 2015 ozone NAAQS, the Moderate 
area attainment date will be in the summer of 2024, and the last full 
year of monitored ozone-season data that will inform attainment 
demonstrations is, therefore, 2023.
    The EPA's interpretation of the good neighbor requirements in 
relation to the Marginal area attainment date is consistent with the 
Wisconsin opinion. For the reasons explained below, the court's holding 
does not contradict the EPA's view that 2023 is an appropriate analytic 
year in evaluating good neighbor SIPs for the 2015 ozone NAAQS. The 
court in Wisconsin was concerned that allowing upwind emission 
reductions to be implemented after the applicable attainment date would 
require downwind states to obtain more emissions reductions than the 
Act requires of them, to make up for the absence of sufficient 
emissions reductions from upwind states. See 938 F.3d at 316. As 
discussed previously, however, this equitable concern only arises for 
nonattainment areas classified as Moderate or higher for which downwind 
states are required by the CAA to develop attainment plans securing 
reductions from existing sources and demonstrating how such areas will 
attain by the attainment date. See, e.g., CAA section 182(b)(1) & (2) 
(establishing ``reasonable further progress'' and ``reasonably 
available control technology'' requirements for Moderate nonattainment 
areas). Ozone nonattainment areas classified as Marginal are not 
required to meet these same planning requirements, and thus the 
equitable concerns raised by the Wisconsin court do not arise with 
respect to downwind areas subject to the Marginal area attainment date.
    The distinction between planning obligations for Marginal 
nonattainment areas and higher classifications was not before the court 
in Wisconsin. Rather, the court was considering whether the EPA, in 
implementing its obligation to promulgate federal implementation plans 
under CAA section 110(c), was required to fully resolve good neighbor 
obligations by the 2018 Moderate area attainment date for the 2008 
ozone NAAQS. See 938 F.3d at 312-13. Although the court noted that 
petitioners had not ``forfeited'' an argument with respect to the 
Marginal area attainment date, see id. at 314, the court did not 
address whether its holding with respect to the 2018 Moderate area date 
would have applied with equal force to the Marginal area attainment 
date because that date had already passed. Thus, the court did not have 
the opportunity to consider these differential planning obligations in 
reaching its decision regarding the EPA's obligations relative to the 
then-applicable 2018 Moderate area attainment date because such 
considerations were not applicable to the case before the court.\21\ 
For the reasons discussed here, the equitable concerns supporting the 
Wisconsin court's holding as to upwind state obligations relative to 
the Moderate area attainment date also support the EPA's interpretation 
of the good neighbor provision relative to the Marginal area attainment 
date. Thus, the EPA proposes to conclude that its reliance on an 
evaluation of air quality in the 2023 analytical year for purposes of 
assessing good neighbor obligations with respect to the 2015 ozone 
NAAQS is based on a reasonable interpretation of the CAA and legal 
precedent.
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    \21\ The D.C. Circuit, in a short judgment, subsequently vacated 
and remanded the EPA's action purporting to fully resolve good 
neighbor obligations for certain states for the 2008 ozone NAAQS, 
referred to as the CSAPR Close-Out, 83 FR 65878 (December 21, 2018). 
New York v. EPA, No. 19-1019 (October 1, 2019). That result 
necessarily followed from the Wisconsin decision, because as the EPA 
conceded, the Close-Out ``relied upon the same statutory 
interpretation of the Good Neighbor Provision'' rejected in 
Wisconsin. Id. slip op. at 3. In the Close-Out, the EPA had analyzed 
the year 2023, which was two years after the Serious area attainment 
date for the 2008 ozone NAAQS and not aligned with any attainment 
date for that NAAQS. Id. at 2. In New York, as in Wisconsin, the 
court was not faced with addressing specific issues associated with 
the unique planning requirements associated with the Marginal area 
attainment date.
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    As previously discussed, the March 2018 memorandum identifies 
potential downwind nonattainment and maintenance receptors, using the 
definitions applied in the CSAPR Update and using both the ``3 x 3'' 
and the ``no water'' approaches to calculating future year design 
values. The March 2018 memorandum identifies 57 potential nonattainment 
and maintenance receptors in the West in Arizona (2), California (49), 
and Colorado (6).\22\ The March 2018 memorandum also provides 
contribution data regarding the impact of other states on the potential 
receptors. For purposes of evaluating Idaho's 2015 ozone NAAQS 
interstate transport SIP submission, we propose that, at least where a 
state's impacts are less than one percent to downwind nonattainment and 
maintenance sites, it is reasonable to conclude that the state's impact 
will not significantly contribute to nonattainment or interfere with

[[Page 3879]]

maintenance of the NAAQS in any other state. This is consistent with 
our prior action on Idaho's SIP with respect to the 2008 ozone NAAQS 
\23\ and with the EPA's approach to both the 1997 and 2008 ozone NAAQS 
in CSAPR and the CSAPR Update. The EPA notes, nonetheless, that 
consistent with the August 2018 memorandum, it may be reasonable and 
appropriate for states to use a 1 ppb contribution threshold, as an 
alternative to a one percent threshold, at step 2 of the four-step 
framework in developing their SIP revisions addressing the good 
neighbor provision for the 2015 ozone NAAQS. However, for the reasons 
discussed below, it is unnecessary for the EPA to determine whether it 
may be appropriate to apply a 1 ppb threshold for purposes of this 
action.
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    \22\ The number of receptors in the identified western states is 
57, irrespective of whether the ``3 x 3'' or ``no water'' approach 
is used. Further, although the EPA has indicated that states may 
have flexibilities to apply a different analytic approach to 
evaluating interstate transport, including identifying downwind air 
quality problems, because the EPA is also concluding in this 
proposed action that Idaho will have an insignificant impact on any 
potential receptors identified in its analysis, Idaho need not 
definitively determine whether the identified monitoring sites 
should be treated as receptors for the 2015 ozone standard.
    \23\ 80 FR 78981 (December 18, 2015).
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    The EPA's updated 2023 modeling discussed in the March 2018 
memorandum indicates that Idaho's largest impact on any potential 
downwind nonattainment and maintenance receptor in any other Western 
state is 0.18 ppb and 0.19 ppb, respectively.\24\ These values are less 
than 0.70 ppb (one percent of the 2015 ozone NAAQS),\25\ and as a 
result, demonstrate that emissions from Idaho are not linked to any 
2023 downwind potential nonattainment and maintenance receptors 
identified in the March 2018 memorandum. The projected impacts from 
Idaho to potential receptors in the East is even lower. Accordingly, we 
propose to conclude that emissions from Idaho will not contribute to 
any potential receptors, and thus, the state will not significantly 
contribute to nonattainment or interfere with maintenance of the NAAQS 
in any other state.
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    \24\ The EPA's analysis indicates that Idaho will have a 0.18 
ppb impact at the potential nonattainment receptor in Douglas, 
Colorado (Site ID 80350004), which has a 2023 projected average 
design value of 71.1 ppb, a 2023 projected maximum design value of 
73.2 ppb, and had a 2014-2016 design value of 77 ppb. The EPA's 
analysis further indicates that Idaho will have a 0.19 ppb impact at 
a potential maintenance receptor in Arapahoe, Colorado (Site ID 
80050002), which has which has a projected 2023 average design value 
of 69.3 ppb, and a 2023 projected maximum design value of 71.3 ppb. 
See the March 2018 memorandum, attachment C.
    \25\ Because none of Idaho's impacts equal or exceed 0.70 ppb, 
they necessarily also do not equal or exceed the 1 ppb contribution 
threshold discussed in the August 2018 memorandum.
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    The EPA has also assessed Idaho's analysis of potential transport 
to the Fort Hall Reservation in southeast Idaho. As discussed 
previously, the EPA's modeling did not identify receptors in Idaho. 
Additionally, the ozone monitoring sites in Idaho are projected to 
remain below the current standard in 2023. The Idaho Falls area 
monitoring site (Site ID 160230101), which is nearest to the Fort Hall 
Reservation, had a 2014-2016 design value of 60 ppb and the EPA's 
modeling projects a 2023 maximum design value of 60.2 ppb and a 2023 
average design value of 59.6 ppb, both below the 70 ppb standard. The 
Boise area monitoring site with the highest 2023 projected ozone 
concentrations (Site ID 160010017) had a 2014-2016 design value of 67 
ppb and the EPA's modeling projects a 2023 maximum design value of 59.8 
ppb and a 2023 average design value of 59.4 ppb.\26\ We therefore 
propose to find that emissions from Idaho will not significantly 
contribute to nonattainment or interfere with maintenance of the 2015 
ozone NAAQS at the Fort Hall Reservation.
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    \26\ In attachment A of the 2017 memorandum, the EPA provided 
the projected ozone design values at individual monitoring sites 
nationwide. The data for the Idaho monitors is presented on page A-
10.
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IV. Proposed Action

    As discussed in section II of this preamble, Idaho concluded that 
emissions from sources in the state will not significantly contribute 
to nonattainment or interfere with maintenance of the 2015 ozone NAAQS 
in any other state. The EPA's evaluation of Idaho's submission, 
discussed in section III of this preamble, confirms this finding. We 
are proposing to approve the Idaho submission as meeting CAA section 
110(a)(2)(D)(i)(I) requirements for the 2015 ozone NAAQS. The EPA is 
requesting comments on the proposed approval.

V. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, the EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. 
Accordingly, this proposed action merely approves state law as meeting 
Federal requirements and does not impose additional requirements beyond 
those imposed by state law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     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 it does not involve technical standards; 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).
    The proposed SIP would not be approved to apply on any Indian 
reservation land or in any other area where the EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction. In those areas of 
Indian country, the proposed rule does not have tribal implications and 
will not impose substantial direct costs on tribal governments or 
preempt tribal law as specified by Executive Order 13175 (65 FR 67249, 
November 9, 2000).

List of Subjects in 40 CFR Part 52

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

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

    Dated: January 6, 2020.
Chris Hladick,
Regional Administrator, Region 10.
[FR Doc. 2020-00888 Filed 1-22-20; 8:45 am]
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