[Federal Register Volume 85, Number 15 (Thursday, January 23, 2020)]
[Proposed Rules]
[Pages 3874-3879]
[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<PHONE_NUMBER>, or
<EMAIL_ADDRESS>
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

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

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

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

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

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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