Document ID: EPA-R01-OAR-2021-0250-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Maine and New Hampshire; 2015 Ozone NAAQS Interstate Transport Requirements
Posted Date: 2021-06-10T04:00Z

[Federal Register Volume 86, Number 110 (Thursday, June 10, 2021)]
[Proposed Rules]
[Pages 30854-30860]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-12079]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R01-OAR-2021-0250; FRL-10024-67-Region 1]

Air Plan Approval; Maine and New Hampshire; 2015 Ozone NAAQS 
Interstate Transport Requirements

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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[[Page 30855]]

SUMMARY: The Clean Air Act (CAA) requires each State Implementation 
Plan (SIP) to contain adequate provisions prohibiting emissions that 
will have certain adverse air quality effects in other states. The 
States of Maine and New Hampshire each made submissions to the 
Environmental Protection Agency (EPA) to address these requirements for 
the 2015 ozone National Ambient Air Quality Standards (NAAQS). EPA is 
proposing to approve the submissions for each state 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 July 12, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R01-
OAR-2021-0250 at https://www.regulations.gov, or via email to 
simcox.alison@epa.gov. For comments submitted at Regulations.gov, 
follow the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e. on the web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit https://www.epa.gov/dockets/commenting-epa-dockets. Publicly 
available docket materials are available at https://www.regulations.gov 
or at the U.S. Environmental Protection Agency, EPA Region 1 Regional 
Office, Air and Radiation Division, 5 Post Office Square--Suite 100, 
Boston, MA. EPA requests that if at all possible, you contact the 
contact listed in the FOR FURTHER INFORMATION CONTACT section to 
schedule your inspection. The Regional Office's official hours of 
business are Monday through Friday, 8:30 a.m. to 4:30 p.m., excluding 
legal holidays and facility closures due to COVID-19.

FOR FURTHER INFORMATION CONTACT: Alison C. Simcox, Air Quality Branch, 
U.S. Environmental Protection Agency, EPA Region 1, 5 Post Office 
Square--Suite 100, (Mail code 05-2), Boston, MA 02109-3912, tel. (617) 
918-1684, email simcox.alison@epa.gov.

SUPPLEMENTARY INFORMATION: 
    Throughout this document whenever ``we,'' ``us,'' or ``our'' is 
used, we mean EPA.

Table of Contents

I. Background
II. Maine Submission
III. New Hampshire Submission
IV. EPA Evaluation of the States' Submittals
V. Proposed Action
VI. Statutory and Executive Order Reviews

I. Background

    On October 1, 2015, 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, SIP submissions meeting the 
applicable requirements of section 110(a)(2).\2\ One of these 
applicable requirements is found in section 110(a)(2)(D)(i)(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. 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 interfere with maintenance of the NAAQS in another 
state (prong 2). EPA and states must give independent significance to 
prong 1 and prong 2 when evaluating downwind air quality problems under 
CAA 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 
section 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 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,\4\ the Cross-State Air 
Pollution Rule Update (CSAPR Update), and, most recently, the Revised 
CSAPR Update for the 2008 ozone NAAQS.5 6
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    \4\ See 76 FR 48208 (August 8, 2011).
    \5\ Wisconsin v. EPA remanded the CSAPR Update to the extent it 
failed to require upwind states to eliminate their significant 
contribution by the next applicable attainment date by which 
downwind states must come into compliance with the NAAQS, as 
established under CAA section 181(a). Wisconsin v. EPA, 938 F.3d 
303, 313 (D.C. Cir. 2019).
    \6\ The Revised Cross-State Air Pollution Rule Update for the 
2008 Ozone NAAQs (86 FR 23054 (April 30, 2021)) was signed by the 
EPA Administrator on March 15, 2021, and responded to the remand of 
the CSAPR Update (81 FR 74504 October 26, 2016)) and the vacatur of 
a separate rule, the CSAPR Close-Out (83 FR 65878 (December 21, 
2018)) by the D.C. Circuit. Wisconsin v. EPA, 938 F.3d 303 (D.C. 
Cir. 2019); New York v. EPA, 781 F. App'x. 4 (D.C. Cir. 2019).
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    Through the development and implementation of CSAPR and other 
regional rulemakings pursuant to the good neighbor provision,\7\ 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: (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 air-
quality and cost 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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    \7\ In addition to the CSAPR rulemakings, 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).
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    EPA has released several documents containing information relevant 
to evaluating interstate transport with

[[Page 30856]]

respect to the 2015 ozone NAAQS. First, on January 6, 2017, EPA 
published a notice of data availability (NODA) with preliminary 
interstate ozone transport modeling with projected ozone design values 
(DVs) for 2023 using a 2011 base year platform, on which we requested 
public comment.\8\ In the NODA, EPA used the year 2023 as the analytic 
year for this preliminary modeling because that year aligns with the 
expected attainment year for Moderate ozone nonattainment areas for the 
2015 ozone NAAQS.\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, and 
noted that the modeling may be useful for states developing SIPs to 
address good neighbor obligations for the 2008 ozone NAAQS.\10\ On 
March 27, 2018, we issued a memorandum (March 2018 memorandum) noting 
that the same 2023 modeling data released in the 2017 memorandum could 
also be useful for identifying potential downwind air quality problems 
with respect to the 2015 ozone NAAQS at step 1 of the four-step 
interstate transport framework. The March 2018 memorandum also included 
the then newly available contribution modeling results to assist states 
in evaluating their impact on potential downwind air quality problems 
for the 2015 ozone NAAQS under step 2 of the interstate transport 
framework. EPA subsequently issued two more memoranda in August and 
October 2018, providing additional information to states developing 
good neighbor SIP submissions for the 2015 ozone NAAQS concerning, 
respectively, potential contribution thresholds that may be appropriate 
to apply in step 2 of the framework, and considerations for identifying 
downwind areas that may have problems maintaining the standard at step 
1 of the framework.\11\
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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 1733, 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.
    \11\ 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/meme-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
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    On October 30, 2020, in the Notice of Proposed Rulemaking for the 
Revised CSAPR Update, EPA released and accepted public comment on 
updated 2023 modeling that used a 2016 emissions platform developed 
under EPA/Multi-Jurisdictional Organization (MJO)/state collaborative 
project as the primary source for the base year and future year 
emissions data.\12\ On March 15, 2021, EPA signed the final Revised 
CSAPR Update using the same modeling released at proposal.\13\ Although 
Maine and New Hampshire relied on the modeling included in the March 
2018 memo to develop their SIP submissions as EPA had suggested, EPA 
now proposes to primarily rely on the updated and newly available 2016 
base year modeling in evaluating these submissions. By using the 
updated modeling results, EPA is using the most current and technically 
appropriate information as the primary basis for this proposed 
rulemaking. EPA's independent analysis, which also evaluated historical 
monitoring data, recent DVs, and emissions trends, found that such 
information provides additional support and further substantiates the 
results of the 2016 base year modeling as the basis for this proposed 
rulemaking. Section III of this notice and the Air Quality Modeling 
technical support document (TSD) included in the docket for this 
proposal contain additional detail on this modeling.\14\
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    \12\ See 85 FR 68964, 68981. The results of this modeling are 
included in a spreadsheet in the docket for this action. The 
underlying modeling files are available for public review in the 
docket for the Revised CSAPR Update (EPA-HQ-OAR-2020-0272).
    \13\ See 86 FR 23054 at 23075, 23164 (April 30, 2021).
    \14\ See ``Air Quality Modeling Technical Support Document for 
the Revised Cross-State Air Pollution Rule Update,'' 86 FR 23054 
(April 30, 2021), available in the docket for this action. This TSD 
was originally developed to support EPA's action in the Revised 
CSAPR Update, as relating to outstanding good neighbor obligations 
under the 2008 ozone NAAQS. While developed in this separate 
context, the data and modeling outputs, including interpolated 
design values for 2021, may be evaluated with respect to the 2015 
ozone NAAQS and used in support of this proposal.
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    In the CSAPR, CSAPR Update, and the Revised CSAPR Update, EPA used 
a threshold of one percent of the NAAQS to determine whether a given 
upwind state was ``linked'' at step 2 of the interstate transport 
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 EPA, therefore, 
concluded the state would 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, 
considering both air quality and cost considerations, to determine 
what, if any, emissions might be deemed ``significant'' and, thus, must 
be eliminated under the good neighbor provision. EPA is proposing to 
rely on the one percent threshold for the purpose of evaluating Maine 
and New Hampshire's contributions to nonattainment or maintenance of 
the 2015 ozone NAAQS in downwind areas.
    Several D.C. Circuit court decisions address the issue of the 
relevant analytic year for the purposes of evaluating ozone transport 
air-quality problems. On September 13, 2019, the D.C. Circuit issued a 
decision in Wisconsin v. EPA, remanding the CSAPR Update to the extent 
that it failed to require upwind states to eliminate their significant 
contribution by the next applicable attainment date by which downwind 
states must come into compliance with the NAAQS, as established under 
CAA section 181(a). 938 F.3d 303, 313.
    On May 19, 2020, the D.C. Circuit issued a decision in Maryland v. 
EPA that cited the Wisconsin decision in holding that EPA must assess 
the impact of interstate transport on air quality at the next downwind 
attainment date, including Marginal area attainment dates, in 
evaluating the basis for EPA's denial of a petition under CAA section 
126(b). Maryland v. EPA, 958 F.3d 1185, 1203-04 (D.C. Cir. 2020). The 
court noted that ``section 126(b) incorporates the Good Neighbor 
Provision,'' and, therefore, ``EPA must find a violation [of section 
126] if an upwind source will significantly contribute to downwind 
nonattainment at the next downwind attainment deadline. Therefore, the 
agency must evaluate downwind air quality at that deadline, not at some 
later date.'' Id. at 1204 (emphasis added). EPA interprets the court's 
holding in Maryland as requiring the Agency, under the good neighbor 
provision, to assess downwind air quality by the next applicable 
attainment date, including a Marginal area attainment date under CAA 
section

[[Page 30857]]

181 for ozone nonattainment.\15\ The Marginal area attainment date for 
the 2015 ozone NAAQS is August 3, 2021.\16\ Historically, EPA has 
considered the full ozone season prior to the attainment as supplying 
an appropriate analytic year for assessing good neighbor obligations. 
While this would be 2020 for an August 2021 attainment date (which 
falls within the 2021 ozone season running from May 1 to September 30), 
in this circumstance, when the 2020 ozone season is wholly in the past, 
it is appropriate to focus on 2021 to address good neighbor obligations 
to the extent possible by the 2021 attainment date. EPA does not 
believe it would be appropriate to select an analytical year that is 
wholly in the past, because the agency interprets the good neighbor 
provision as forward looking. See 86 FR 23054 at 23074; see also 
Wisconsin, 938 F.3d at 322. Consequently, in this proposal EPA will use 
the analytical year of 2021 to evaluate Maine and New Hampshire's good 
neighbor obligations with respect to the 2015 ozone NAAQS.
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    \15\ We note that the court in Maryland did not have occasion to 
evaluate circumstances in which EPA may determine that an upwind 
linkage to a downwind air quality problem exists at steps 1 and 2 of 
the interstate transport framework by a particular attainment date, 
but for reasons of impossibility or profound uncertainty the Agency 
is unable to mandate upwind pollution controls by that date. See 
Wisconsin, 938 F.3d at 320. The D.C. Circuit noted in Wisconsin that 
upon a sufficient showing, these circumstances may warrant 
flexibility in effectuating the purpose of the good neighbor 
provision. Such circumstances are not at issue in the present 
proposal.
    \16\ CAA section 181(a); 40 CFR 51.1303; Additional Air Quality 
Designations for the 2015 Ozone National Ambient Air Quality 
Standards, 83 FR 25776 (June 4, 2018, effective Aug. 3, 2018).
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II. Maine Submission

    On February 6, 2020, Maine submitted a SIP revision addressing the 
CAA section 110(a)(2)(D)(i)(I) interstate transport requirements for 
the 2015 ozone NAAQS.
    Maine 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 Maine in the year 2023. These results 
indicate Maine's greatest impact on any potential downwind 
nonattainment or maintenance receptor would be 0.01 ppb in Suffolk 
County, New York (monitoring site 361030002). Maine compared this value 
to a screening threshold of 0.70 ppb, representing one percent of the 
2015 ozone NAAQS. Because Maine's impacts to receptors in downwind 
states are projected to be less than 0.70 ppb in 2023, Maine concluded 
that emissions from sources within the state will not significantly 
contribute to nonattainment or interfere with maintenance of the 2015 
ozone NAAQS in any other state.

III. New Hampshire Submission

    On September 5, 2018, New Hampshire submitted a SIP revision 
addressing the CAA section 110(a)(2)(D)(i)(I) interstate transport 
requirements for the 2015 ozone NAAQS. This ``good neighbor SIP'' was 
included as an enclosure in the state's infrastructure SIP for the same 
NAAQS.
    New Hampshire 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 New Hampshire in the year 2023. These results 
indicate New Hampshire's greatest impact on any potential downwind 
nonattainment or maintenance receptor would be 0.06 ppb in Queens 
County, New York (monitoring site 360810124). New Hampshire compared 
this value to a screening threshold of 0.70 ppb, representing one 
percent of the 2015 ozone NAAQS. Because New Hampshire's impacts to 
receptors in downwind states are projected to be less than 0.70 ppb in 
2023,\17\ New Hampshire concluded that emissions from sources within 
the state will not significantly contribute to nonattainment or 
interfere with maintenance of the 2015 ozone NAAQS in any other state.
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    \17\ New Hampshire incorrectly stated in its September 2018 good 
neighbor SIP submission that the state's highest projected 
contribution for 2023 to any downwind nonattainment or maintenance 
receptor is 6 ppb; the modeled value should be 0.06 ppb as correctly 
shown in Table 1 of the submission. New Hampshire also incorrectly 
stated in their submission that 7 ppb, rather than 0.70 ppb, is 1% 
of the NAAQS.
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    New Hampshire's September 2018 good neighbor SIP submission also 
lists New Hampshire's regulations for controlling emissions of ozone 
precursors as well as its regional emissions-control strategies. These 
include Env-A 619, Prevention of Significant Deterioration (PSD), and 
Env-A 618, Nonattainment New Source Review (NNSR) (82 FR 24057; May 25, 
2017); and Env-A 2300, Mitigation of Regional Haze (77 FR 50602; August 
22, 2012).

IV. EPA Evaluation of the States' Submittals

    Maine and New Hampshire's SIP submissions both rely on analysis of 
the year 2023 to show that each state does not significantly contribute 
to nonattainment or interfere with maintenance of the 2015 ozone NAAQS 
in any other state. However, given the holdings in Wisconsin and 
Maryland, analysis of that year is no longer sufficient where the next 
attainment date for the 2015 ozone NAAQS is in 2021.\18\ Nonetheless, 
the analysis EPA conducted for the 2021 analytical year corroborates 
the conclusion reached in each state's submission.
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    \18\ We recognize that Maine, New Hampshire, and other states 
may have been influenced by EPA's 2018 guidance memos (issued prior 
to the Wisconsin and Maryland decisions) in making good neighbor 
submissions that relied on EPA's modeling of 2023. When there are 
intervening changes in relevant law or legal interpretation of CAA 
requirements, states are generally free to withdraw, supplement, 
and/or re-submit their SIP submissions with new analysis (in 
compliance with CAA procedures for SIP submissions). While neither 
Maine nor New Hampshire has done this, as explained in this section, 
the independent analysis EPA has conducted at its discretion 
confirms that the states' submissions in this instance are 
ultimately approvable.
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    As stated in Section I of this notice, in consideration of the 
holdings in Wisconsin and Maryland, EPA's analysis relies on 2021 as 
the relevant attainment year for evaluating a State's good neighbor 
obligations with respect to the 2015 ozone NAAQS using the four-step 
interstate transport framework. In step 1, we identify locations where 
the Agency expects there to be nonattainment or maintenance receptors 
for the 2015 8-hour ozone NAAQS in the 2021 analytic future year. Where 
EPA's analysis shows that an area or site does not fall under the 
definition of a nonattainment or maintenance receptor in 2021, that 
site is excluded from further analysis under EPA's four step interstate 
transport framework.\19\ For areas that are identified as a 
nonattainment or maintenance receptor in 2021, we proceed to the next 
step of our four-step framework by identifying the upwind state's 
contribution to those receptors.
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    \19\ While EPA has focused its analysis in this notice on the 
year 2021, modeling data in the record for years 2023 and 2028 
confirm that no new linkages to downwind receptors are projected for 
these states in later years. This is not surprising as it is 
consistent with an overall, long-term downward trend in emissions 
from these states.
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    EPA's approach to identifying ozone nonattainment and maintenance 
receptors in this action is consistent with the approach used in 
previous transport rulemakings. EPA's approach gives independent 
consideration to both the ``contribute significantly to nonattainment'' 
and the ``interfere with maintenance'' prongs of section 
110(a)(2)(D)(i)(I), consistent with the

[[Page 30858]]

D.C. Circuit's direction in North Carolina.\20\
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    \20\ 531 F.3d at 910-911 (holding that EPA must give 
``independent significance'' to each prong of CAA section 
110(a)(2)(D)(i)(I)).
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    For the purpose of this proposal, EPA identifies nonattainment 
receptors as those monitoring sites that are projected to have average 
design values that exceed the NAAQS and that are also measuring 
nonattainment based on the most recent monitored design values. This 
approach is consistent with prior transport rulemakings, such as CSAPR 
Update, where EPA defined nonattainment receptors as those areas that 
both currently monitor nonattainment and that EPA projects will be in 
nonattainment in the future analytic year.\21\
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    \21\ See 81 FR 74504 (October 26, 2016). Revised CSAPR Update 
also used this approach. See 86 FR 23054 (April 30, 2021). This same 
concept, relying on both current monitoring data and modeling to 
define nonattainment receptor, was also applied in CAIR. See 70 FR 
25241 (January 14, 2005). See also North Carolina, 531 F.3d at 913-
914 (affirming as reasonable EPA's approach to defining 
nonattainment in CAIR).
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    In addition, in this proposal, EPA identifies a receptor to be a 
``maintenance'' receptor for purposes of defining interference with 
maintenance, consistent with the method used in the CSAPR and upheld by 
the D.C. Circuit in EME Homer City Generation, L.P. v. EPA, 795 F.3d 
118, 136 (D.C. Cir. 2015).\22\ Specifically, monitoring sites with a 
projected maximum design value in 2021 that exceeds the NAAQS are 
considered maintenance receptors. EPA's method of defining these 
receptors takes into account both measured data and reasonable 
projections based on modeling analysis.
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    \22\ See 76 FR 48208 (August 8, 2011). CSAPR Update and Revised 
CSAPR Update also used this approach. See 81 FR 74504 (October 26, 
2016) and See 86 FR 23054 (April 30, 2021).
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    Recognizing that nonattainment receptors are also, by definition, 
maintenance receptors, EPA often uses the term ``maintenance-only'' to 
refer to receptors that are not also nonattainment receptors. 
Consistent with the methodology described above, monitoring sites with 
a projected maximum design value that exceeds the NAAQS, but with a 
projected average design value that is below the NAAQS, are identified 
as maintenance-only receptors. In addition, those sites that are 
currently measuring ozone concentrations below the level of the 
applicable NAAQS, but are projected to be nonattainment based on the 
average design value and that, by definition, are projected to have a 
maximum design value above the standard are also identified as 
maintenance-only receptors.
    To evaluate future air quality in steps 1 and 2 of the interstate 
transport framework, EPA is using the 2016 and 2023 base case emissions 
developed under EPA/MJO/state collaborative emissions modeling platform 
project as the primary source for base year and 2023 future year 
emissions data for this proposal.\23\ Because this platform does not 
include emissions for 2021, EPA developed an interpolation technique 
based on modeling for 2023 and measured ozone data to determine ozone 
concentrations for 2021. To estimate average and maximum design values 
for 2021, EPA first performed air quality modeling for 2016 and 2023 to 
obtain design values in 2023. The 2023 design values were then coupled 
with the corresponding 2016 measured design values to estimate design 
values in 2021. Details on the modeling, including the interpolation 
methodology, can be found in the Air Quality Modeling TSD, found in the 
docket of this proposal.
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    \23\ See 86 FR 23054 (April 30, 2021). The results of this 
modeling are included in a spreadsheet in the docket for this 
action. The underlying modeling files are available for public 
access in the docket for the Revised CSAPR Update (EPA-HQ-OAR-2020-
0272).
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    To quantify the contribution of emissions from specific upwind 
states on 2021 8-hour design values for the identified downwind 
nonattainment and maintenance receptors, EPA first performed 
nationwide, state-level ozone source apportionment modeling for 2023. 
The source apportionment modeling provided contributions to ozone from 
precursor emissions of anthropogenic nitrogen oxides (NOX) 
and volatile organic compounds (VOCs) in each state, individually. The 
modeled contributions were then applied in a relative sense to the 2021 
average design value to estimate the contributions in 2021 from each 
state to each receptor. Details on the source apportionment modeling 
and the methods for determining contributions in 2021 are in the Air 
Quality Modeling TSD in the docket.
    The 2021 design values and contributions were examined to determine 
if Maine and New Hampshire, considered separately, contribute at or 
above the threshold of one percent of the 2015 ozone NAAQS (0.70 ppb) 
to any downwind nonattainment or maintenance receptor. The data \24\ 
indicate that the highest contribution in 2021 from Maine to a downwind 
nonattainment or maintenance receptor is 0.01 ppb to a maintenance 
receptor in Fairfield County, Connecticut (monitoring site 90013007), 
and, from New Hampshire, is 0.10 ppb to the same downwind receptor. The 
data also show modeled ozone contributions from Maine and New Hampshire 
to the design values of a larger set of monitoring sites (independent 
of attainment status) and indicate that the highest projected 
contribution in 2021 from Maine to any of these sites is 0.12 ppb to 
monitors in Putnam and Westchester Counties in New York (monitoring 
sites 360790005 and 361192004; #307 and #314 on the Design Values and 
Contributions spreadsheet), and, from New Hampshire, is 1.46 ppb to the 
monitor in Knox County, Maine (monitoring site 230130004; #226 on the 
Design Values and Contributions spreadsheet). While New Hampshire's 
modeled contribution to the Knox County monitor exceeds one percent of 
the 2015 ozone NAAQS, EPA's analysis at step 1 does not identify the 
Knox County monitor as a downwind area that may have problems 
maintaining the 2015 ozone NAAQS. The Knox County monitor's projected 
design value in 2021 is 57.4 ppb.
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    \24\ The data are given in the ``Air Quality Modeling Technical 
Support Document for the Revised Cross-State Air Pollution Rule 
Update'' and ``Ozone Design Values and Contributions Revised CSAPR 
Update.xlsx,'' which are included in the docket for this action.
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    EPA also analyzed emissions trends for ozone precursors in Maine 
and New Hampshire to support the findings from the air quality 
analysis. In evaluating emissions trends, we first reviewed the 
information submitted by each state and then reviewed additional 
information available to the Agency. We focused on state-wide emissions 
of nitrogen oxides and volatile organic compounds.25 26 
Emissions from mobile sources, electric generating units (``EGUs''), 
industrial facilities, gasoline vapors, and chemical solvents are some 
of the major anthropogenic sources of ozone precursors. This evaluation 
looks at both past emissions trends, as well as projected trends.
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    \25\ This is because ground-level ozone is not emitted directly 
into the air but is formed by chemical reactions between ozone 
precursors, chiefly NOX and non-methane VOCs, in the 
presence of sunlight.
    \26\ 81 FR 74504, 74513-14.
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    As shown in Table 1, for Maine, between 2016 and 2023, annual total 
NOX and VOC emissions are projected to decline by 38 percent 
and 20 percent, respectively. For New Hampshire, between 2016 and 2023, 
annual total NOX and VOC emissions are projected to decline 
by 36 percent and 15 percent, respectively. The projected reductions 
are a result of the implementation of existing control programs that 
will continue to decrease NOX and VOC emissions in Maine and 
New

[[Page 30859]]

Hampshire, as indicated by EPA's most recent 2021 and 2023 projected 
emissions.
    As shown in Table 2, onroad and nonroad mobile source emissions 
collectively comprise a large portion of each state's total 
anthropogenic NOX and VOC. For example, in 2019, 
NOX emissions from mobile sources in Maine comprised 52 
percent of total NOX emissions and 48 percent of total VOC 
emissions. In New Hampshire for that same year, NOX 
emissions from mobile sources comprised 54 percent of total 
NOX emissions and 45 percent of total VOC emissions.
    The large decrease in NOX emissions between 2016 
emissions and projected 2023 emissions in each state is primarily 
driven by reductions in emissions from onroad and nonroad mobile 
sources. EPA projects that both VOC and NOX emissions will 
continue declining out to 2023 as newer vehicles and engines that are 
subject to the most recent, stringent mobile source standards replace 
older vehicles and engines.\27\
---------------------------------------------------------------------------

    \27\ Tier 3 Motor Vehicle Emission and Fuel Standards (79 FR 
23414, April 28, 2014); Mobile Source Air Toxics Rule (MSAT2) (72 FR 
8428, February 26, 2007), Heavy-Duty Engine and Vehicle Standards 
and Highway Diesel Fuel Sulfur Control Requirements (66 FR 5002, 
January 18, 2001); Clean Air Nonroad Diesel Rule (69 FR 38957, June 
29, 2004); Locomotive and Marine Rule (73 FR 25098, May 6, 2008); 
Marine Spark-Ignition and Small Spark-Ignition Engine Rule (73 FR 
59034, October 8, 2008); New Marine Compression-Ignition Engines at 
or Above 30 Liters per Cylinder Rule (75 FR 22895, April 30, 2010); 
and Aircraft and Aircraft Engine Emissions Standards (77 FR 36342, 
June 18, 2012).
---------------------------------------------------------------------------

    In summary, there is no evidence to suggest that the overall 
emissions trend demonstrated in Table 1 in either state will suddenly 
reverse or spike in 2021 compared to historical emissions levels or 
those projected for 2023. Further, there is no evidence that the 
projected ozone precursor emissions trends out to 2023 and beyond would 
not continue to show a decline in emissions. In addition, EPA's normal 
practice is to include in our modeling only changes in NOX 
or VOC emissions that result from final regulatory actions. Any 
potential changes in NOX or VOC emissions that may result 
from possible future or proposed regulatory actions are speculative.
    This downward trend in emissions in Maine and New Hampshire adds 
support to the air quality analyses presented above for each state, and 
indicates that the contributions from emissions from sources in Maine 
and New Hampshire to ozone receptors in downwind states will continue 
to decline and, for each state, remain below one percent of the NAAQS.
---------------------------------------------------------------------------

    \28\ The annual emissions data for the years 2011 through 2019 
were obtained from EPA's National Emissions Inventory website: 
https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data. Note that emissions from miscellaneous 
sources are not included in the state totals. The emissions for 2021 
and 2023 are based on the 2016 emissions modeling platform. See 
``2005 thru 2019 + 2021_2023_2028 Annual State Tier1 Emissions'' and 
the Emissions Modeling TSD in the docket for this action.

                                                 Table 1--Annual Emissions of NOX and VOC From Anthropogenic Sources in Maine and New Hampshire
                                                                                      [Tons per year] \28\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  2011       2012       2013       2014       2015       2016       2017       2018       2019    Projected 2021  Projected 2023
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ME NOx.......................................................     59,773     57,292     54,812     52,332     51,871     49,148     49,889     48,440     46,542          33,996          30,536
ME VOC.......................................................     64,079     61,860     59,641     57,422     54,686     49,630     48,284     47,024     45,665          41,197          39,562
NH NOx.......................................................     36,554     37,065     37,577     38,086     35,025     30,775     28,530     27,408     25,680          21,822          19,579
NH VOC.......................................................     45,859     44,159     42,459     40,731     38,275     34,234     33,026     31,928     31,193          29,640          28,872
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

                                              Table 2--Annual Emissions of NOX and VOC From Onroad and Nonroad Vehicles in Maine and New Hampshire
                                                                                         [Tons per year]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  2011       2012       2013       2014       2015       2016       2017       2018       2019    Projected 2021  Projected 2023
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ME...........................................................     41,601     38,861     36,122     33,382     31,465     27,286     26,570     25,714     24,005          17,841          16,214
NOx..........................................................
ME VOC.......................................................     40,376     38,091     35,805     33,519     30,884     25,929     24,683     23,423     22,064          18,037          16,499
NH NOx.......................................................     26,038     24,979     23,921     22,862     20,835     17,619     16,408     15,022     13,970          10,776           9,878
NH VOC.......................................................     25,314     24,184     23,054     21,924     20,027     16,544     15,895     14,796     14,062          11,947          11,277
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Thus, EPA's air quality and emissions analyses indicate that 
emissions from Maine or from New Hampshire, with each state considered 
individually, will not significantly contribute to nonattainment or 
interfere with maintenance of the 2015 ozone NAAQS in any other state 
in 2021.

V. Proposed Action

    As discussed in Sections II and III, Maine and New Hampshire have 
each concluded that emissions from sources in their individual state 
will not contribute to nonattainment or interfere with maintenance of 
the 2015 ozone NAAQS in any other state. Each state submission reached 
this conclusion by relying on information for the analytic year 2023. 
As discussed above, the Wisconsin and Maryland decisions of the D.C. 
Circuit have made clear that the good neighbor analysis for the 2015 
ozone NAAQS must focus on the next attainment date, and that date is 
the Marginal area attainment date in 2021. Therefore, EPA conducted 
additional analysis to determine whether each state's conclusions would 
remain valid in 2021 rather than 2023. EPA's evaluation of measured and 
monitored data, including interpolating values to generate a reasonable 
expectation of air quality and contribution values in 2021, as 
discussed in Section IV, is consistent with conclusions made by Maine 
and New Hampshire that, with each state considered separately, 
emissions from sources in each state will not contribute to 
nonattainment or interference with maintenance of the 2015 ozone NAAQS 
in any other state. Because our analysis corroborates each state's 
conclusion that emissions from within its state do not contribute to 
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in 
another state, we propose to approve the Maine and New Hampshire 
submissions as meeting CAA section 110(a)(2)(D)(i)(I).
    EPA is soliciting public comments on this notice. These comments 
will be considered before taking final action. Interested parties may 
participate in the

[[Page 30860]]

Federal rulemaking procedure by submitting written comments to this 
proposed rule by following the instructions listed in the ADDRESSES 
section of this Federal Register.

VI. 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, 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);
     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 Clean Air Act; 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, the 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, Carbon monoxide, 
Incorporation by reference, Intergovernmental relations, Lead, Nitrogen 
dioxide, Ozone, Particulate matter, Reporting and recordkeeping 
requirements, Sulfur oxides, Volatile organic compounds.

    Dated: June 3, 2021.
Deborah Szaro,
Acting Regional Administrator, EPA Region 1.
[FR Doc. 2021-12079 Filed 6-9-21; 8:45 am]
BILLING CODE 6560-50-P