[Federal Register Volume 84, Number 157 (Wednesday, August 14, 2019)]
[Proposed Rules]
[Pages 40344-40349]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-17406]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R01-OAR-2008-0108; FRL-9998-00-Region 1]


Air Plan Approval; Massachusetts; Transport State Implementation 
Plans for the 1997, 2008, and 2015 Ozone Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve State Implementation Plan (SIP) revisions submitted by the 
State of Massachusetts that address the interstate transport of air 
pollution requirements for Infrastructure SIPs for the 1997, 2008, and 
2015 ozone national ambient air quality standards (NAAQS) (i.e., 
Transport SIPs). The intended effect of this action is to propose 
approval of the Transport SIPs as revisions to the Massachusetts SIP. 
This action is being taken under the Clean Air Act.

DATES: Written comments must be received on or before September 13, 
2019.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R01-
OAR-2008-0108 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, the 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. 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, 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 http://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.

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. The term ``the Commonwealth'' 
refers to the State of Massachusetts.

Table of Contents

I. Background
II. EPA's Evaluation of the State's Submittals
    A. Background and Evaluation of the Transport SIP for the 1997 
Ozone Standard
    B. Background and Evaluation of the Transport SIP for the 2008 
Ozone Standard
    C. Background and Evaluation of the Transport SIP for the 2015 
Ozone Standard
III. Proposed Action
IV. Statutory and Executive Order Reviews

I. Background

    On January 31, 2008, February 9, 2018, and September 27, 2018, the 
Massachusetts Department of Environmental Protection (DEP) submitted 
revisions to its State Implementation Plan (SIP) consisting of 
interstate transport SIPs for the 1997, 2008, and 2015 ozone NAAQS. The 
interstate transport SIPs we are proposing to approve were submitted to 
address the infrastructure requirements of section 110(a)(2)(D)(i)(I) 
of the Clean Air Act (CAA).
    Over the past two decades, EPA has revised the primary ozone 
standard three times. On July 18, 1997, EPA revised the ozone standard 
from 0.120 parts per million (ppm), based on a one-hour average, to 
0.08 ppm, based on a three-year average of the annual fourth-highest 
daily maximum 8-hour average. See 62 FR 38856. On March 12, 2008, EPA 
revised the level of the primary ozone standard from 0.08 ppm to 0.075 
ppm and maintained the form of the standard. See 73 FR 16436. Most 
recently, on October 1, 2015, EPA revised the primary ozone standard by 
lowering the level to 0.070 ppm while maintaining the form of the 
standard. See 80 FR 65292.
    Section 110(a)(1) of the CAA requires states to submit SIPs to 
address a new or revised NAAQS within three years after promulgation of 
a standard, or within a shorter period as EPA may prescribe. Section 
110(a)(2) lists the elements that new SIPs must address, as applicable, 
including section 110(a)(2)(D)(i), which pertains to interstate 
transport of certain emissions.
    The interstate transport SIP provisions require each state to 
submit a SIP that prohibits emissions that have certain adverse effects 
in another state due to interstate transport of air pollution. Section 
110(a)(2)(D)(i) identifies four elements related to the evaluation of 
impacts of interstate transport of air pollutants; in this rulemaking, 
we are addressing the first two elements; the remaining two elements 
will be acted on under separate rulemaking actions. Specifically, the 
portions that we are proposing to approve pertain to section 
110(a)(2)(D)(i)(I): (1) Significant contribution to nonattainment of 
the ozone NAAQS in any other state (commonly called ``prong 1''); and 
(2) interference with maintenance of the ozone NAAQS (commonly called 
``prong 2'') by any other state. These two provisions (or ``prongs'') 
are commonly referred to as the ``good neighbor'' provisions of the 
CAA. The first provision requires that a state's SIP for a new or 
revised NAAQS contain adequate measures to prohibit any source or other 
type of emissions activity in the state from emitting pollutants in 
amounts that ``contribute significantly'' to nonattainment of the NAAQS 
in another state. The second provision requires that a state's SIP 
prohibit any source or other type of emissions activity in the state 
from emitting pollutants in amounts that will ``interfere with 
maintenance'' of the applicable NAAQS in any other state.

[[Page 40345]]

II. EPA's Evaluation of the State's Submittals

A. Background and Evaluation of the Transport SIP for the 1997 Ozone 
Standard

    On April 25, 2005, EPA published a final rule that made a finding 
that all 50 states had failed to submit, pursuant to Section 
110(a)(2)(D)(i) of the CAA, interstate transport SIPs for the 1997 
ozone NAAQS. See 70 FR 21147. Subsequently, on August 15, 2006, EPA 
issued a guidance memorandum that provided recommendations to states 
for making submissions to meet the requirements of section 
110(a)(2)(D)(i) for the 1997 8-hour ozone and 1997 fine-particle 
(PM2.5) standards (2006 Guidance).\1\
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    \1\ Memorandum from William T. Harnett entitled ``Guidance for 
State Implementation Plan (SIP) Submissions to Meet Current 
Outstanding Obligations Under Section 110(a)(2)(D)(i) for the 8-hour 
ozone and PM2.5National Ambient Air Quality Standards'' 
(Aug. 15, 2006).
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    The CAA does not specifically mandate how to determine significant 
contribution to nonattainment or interference with maintenance of the 
NAAQS. Therefore, EPA has interpreted these terms in past regulatory 
actions, such as the 1998 nitrogen oxides (NOX) SIP Call, in 
which EPA took action to address emissions of NOX that 
significantly contributed to nonattainment of, or interfered with 
maintenance of, the then-applicable ozone NAAQS. See 63 FR 57356 
(October 27, 1998).
    The NOX SIP Call was the mechanism through which EPA 
evaluated whether NOX emissions from sources in certain 
states had prohibited interstate impacts, and if they did, required the 
states to adopt SIP revisions to eliminate the NOX emissions 
through participation in a regional cap-and-trade program or by other 
means.
    After promulgation of the 1997 8-hour ozone and PM2.5 
NAAQS, EPA recognized that regional transport was a serious concern 
throughout the eastern United States and, therefore, developed the 2005 
Clean Air Interstate Rule (CAIR) to address emissions of sulfur dioxide 
(SO2) and NOX that exacerbate ambient ozone and 
PM2.5 levels in many downwind areas through interstate 
transport. See 70 FR 25162. In CAIR, EPA interpreted the term 
``interfere with maintenance'' as part of the evaluation of whether the 
emissions of sources in certain states had impacts on areas that could 
put them at risk of violating the NAAQS in a modeled future-year unless 
actions were taken by upwind states to reduce SO2 and 
NOX emissions. Through CAIR, EPA required states that had 
such interstate impacts to adopt SIP revisions to eliminate the 
SO2 and NOX emissions, whether through 
participation in a regional cap-and-trade program or by other means. 
Massachusetts was included in CAIR as a state that, under the 1997 
ozone NAAQS, contributed significantly to ozone-season nonattainment in 
another state.
    EPA's 2006 Guidance addressed CAA section 110(a)(2)(D)(i) 
requirements for the 1997 8-hour ozone and PM2.5 NAAQS. For 
those states subject to CAIR, EPA indicated that compliance with CAIR 
would meet the two requirements of section 110(a)(2)(D)(i)(I) for these 
NAAQS.
    In 2008, the U.S. Court of Appeals for the D.C. Circuit found that 
CAIR and the related CAIR federal implementation plans (FIPs) were 
unlawful.\2\ Among other issues, the court held that EPA had not 
correctly addressed the second element of section 110(a)(2)(D)(i)(I) in 
CAIR and noted that ``EPA gave no independent significance to the 
`interfere with maintenance' prong of section 110(a)(2)(D)(i)(I) to 
separately identify upwind sources interfering with downwind 
maintenance.'' \3\ EPA's approach, the court reasoned, would leave 
areas that are ``barely meeting attainment'' with ``no recourse'' to 
address upwind emissions sources.\4\ The court, therefore, concluded 
that a plain-language reading of the statute requires EPA to give 
independent meaning to the ``interfere with maintenance'' requirement 
of section 110(a)(2)(D)(i)(I) and that the approach used by EPA in CAIR 
failed to do so.
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    \2\ See North Carolina v. EPA, 531 F.3d 896 (D.C. Cir. 2008), 
amended on rehearing, 550 F.3d 1176 (2008).
    \3\ 531 F.3d at 909.
    \4\ Id.
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    On August 8, 2011, to address the judicial remand of CAIR, EPA 
adopted a new rule to address interstate transport of air pollution 
pursuant to section 110(a)(2)(D)(i): ``Federal Implementation Plans: 
Interstate Transport of Fine Particulate Matter and Ozone, and 
Correction of SIP Approvals,'' known as the Cross State Air Pollution 
Rule (CSAPR). See 76 FR 48208. As part of CSAPR, EPA reexamined the 
section 110(a)(2)(D)(i)(I) requirements for the 1997 8-hour ozone and 
PM2.5 NAAQS in other states.\5\ In CSAPR, EPA developed an 
approach to predict which areas that would violate the 1997 8-hour 
ozone and PM2.5 NAAQS in the future, and which areas that 
would be close to the level of these NAAQS and, therefore, at risk of 
becoming nonattainment areas. This approach starts by identifying 
geographic areas for which further evaluation is appropriate and 
differentiates between areas where the concern is ``significant 
contribution to nonattainment'' from those where the concern is 
``interference with maintenance.''
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    \5\ The original CSAPR did not address the 2008 8-hour ozone 
NAAQS.
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    Under CSAPR, EPA evaluated data from air-quality monitors over 
three overlapping 3-year periods (i.e., 2003-2005, 2004-2006, and 2005-
2007), as well as data from air-quality modeling to predict which areas 
would violate the 1997 8-hour ozone and PM2.5 NAAQS in 2012, 
and which areas would have difficulty maintaining attainment. If an 
area's projected monitoring data for 2012 indicated that it would 
violate the NAAQS based on the average of these three overlapping 
periods, then this monitor was considered appropriate for comparison 
for purposes of the ``significant contribution to nonattainment'' 
element. However, if an area's projected data indicated that it would 
violate the NAAQS based on a single period, but not over the average of 
the three periods, then this monitor was considered appropriate for 
comparison for purposes of the ``interfere with maintenance'' element.
    EPA's 2006 Guidance did not specifically recommend this approach to 
states. However, in light of the court's decision on CAIR, EPA used 
this approach to evaluate whether Massachusetts had met its ``good 
neighbor'' obligations with respect to the 1997 ozone standard. In this 
guidance, EPA stated that ``EPA believes that the contents of the SIP 
submission required by section 110(a)(2)(D) may vary, depending upon 
the facts and circumstances related to the specific NAAQS. In 
particular, the data and analytical tools available at the time the 
State develops and submits a SIP for a new or revised NAAQS necessarily 
affects the contents of the required submission.''[thinsp]
    On January 31, 2008, Massachusetts submitted a SIP revision to EPA 
addressing the CAA Section 110(a)(2)(D)(i) ``good neighbor'' 
requirements for the 1997 ozone NAAQS. The Commonwealth's submittal 
noted that EPA's 2006 Guidance indicates that states subject to EPA's 
CAIR can meet their CAA Section 110(a)(2)(D)(i) ``good neighbor'' 
obligations with a state-adopted, SIP-approved CAIR regulation. 
Massachusetts submitted a CAIR regulation to EPA on March 30, 2007, and 
EPA approved it into the Massachusetts SIP on December 3, 2007. See 72 
FR 67854. Massachusetts noted

[[Page 40346]]

that it doubted that the CAIR rule would be adequate to ensure all 
areas in the Eastern U.S. would meet the 1997 ozone NAAQS by the 
required attainment dates, and, therefore, supplemented its submittal 
with information about additional controls measures it had adopted, or 
planned to adopt, that stemmed from a planning effort overseen by the 
Ozone Transport Commission (OTC).
    Although Massachusetts was identified as a state that contributed 
significantly to ozone nonattainment in another state, and, therefore, 
was required under CAIR to reduce ozone-season NOX 
emissions, EPA's August 2011 CSAPR rule reached a different conclusion 
based on an updated analysis of air-quality and emissions data. See 76 
FR 48299. Specifically, Table V.D-7 of the CSAPR rule indicates that 
Massachusetts' largest downwind contribution to nonattainment for ozone 
was 0.0 ppb, and its largest downwind contribution to maintenance for 
ozone was 0.6 ppb. Id. at 48245. These levels are below the 1 percent 
of the standard (0.8 ppb) that EPA established as the contribution 
threshold for the 1997 ozone NAAQS. Accordingly, EPA concluded in CSAPR 
that Massachusetts does not significantly contribute to nonattainment 
or interfere with maintenance of the 1997 ozone NAAQS. Id. at 48236 
(explaining that states whose contributions are below the threshold do 
not violate the Good Neighbor provision). In light of the analysis of 
ozone transport contained in the CSAPR rule, the final determination 
pertaining to Massachusetts in that action, and the Commonwealth's 
continued adoption of VOC and NOX control strategies as 
noted in their January 31, 2008, Transport SIP submittal, we are 
proposing to find that Massachusetts has met its CAA Section 
110(a)(2)(D)(i)(I) ``good neighbor'' SIP obligation for the 1997 ozone 
NAAQS.

B. Background and Evaluation of the Transport SIP for the 2008 Ozone 
Standard

    On March 12, 2008, EPA revised the primary and secondary ozone 
standards from 0.08 parts per million (ppm) to 0.075 ppm. See 73 FR 
16436. As discussed above, upon promulgation of a new or revised NAAQS, 
states have three years to submit the SIP revision under section 
110(a)(2) of the Act, including ``good neighbor'' SIPs. The CAA gives 
EPA a backstop role to issue federal implementation plans (FIPs), as 
appropriate, for states that do not have ``good neighbor'' provisions, 
or other required provisions, approved in their SIP.
    To meet this backstop role for the 2008 ozone NAAQS, EPA updated 
the CSAPR ozone-season program by issuing a final rule on October 26, 
2016, known as the CSAPR Update. See 81 FR 74504. The CSAPR Update 
addressed the summertime (May-September) transport of ozone in the 
eastern United States that crosses state lines to help downwind states 
meet and maintain the 2008 ozone NAAQS.\6\ The CSAPR Update used the 
same framework that was used by EPA in developing CSAPR.\7\ Prior to 
this, on July 13, 2015, EPA published a rule finding that 24 states, 
including Massachusetts, failed to make complete submissions addressing 
the requirements of section 110(a)(2)(D)(i)(I) regarding the 2008 ozone 
NAAQS. See 80 FR 39961.
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    \6\ In the CSAPR Update, EPA issued FIPs to address CAA section 
110(a)(2)(D)(i) obligations for 22 eastern states but determined 
that no FIP was needed for Massachusetts.
    \7\ Key elements of the four-step interstate transport framework 
have been upheld by the Supreme Court in EPA v. EME Homer City 
Generation, L.P., 134 S. Ct. 1584 (2014).
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    Through several previous rulemakings,\8\ EPA, working in 
partnership with states, established a four-step interstate-transport 
framework to address the requirements of the ``good neighbor'' 
provision for the ozone NAAQS.\9\ The four steps are: Step 1--Identify 
downwind receptors that are expected to have problems attaining or 
maintaining the NAAQS; step 2--determine which upwind states contribute 
enough to these identified downwind air quality problems to warrant 
further review and analysis; step 3--identify the emissions reductions 
necessary to prevent an identified upwind state from contributing 
significantly to those downwind air quality problems; and step 4--adopt 
permanent and enforceable measures needed to achieve those emissions 
reductions.
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    \8\ NOX SIP Call. 63 FR 57356 (October 27, 1998); 
Clean Air Interstate Rule (CAIR). 70 FR 25162 (May 12, 2005); Cross-
State Air Pollution Rule (CSAPR). 75 FR 48208 (August 8, 2011); and 
CSAPR Update. 81 FR 74504 (October 26, 2016).
    \9\ The four-step interstate framework has also been used to 
address requirements of the good neighbor provision for some 
previous particulate matter (PM) NAAQS.
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    To apply the first and second steps of the four-step interstate-
transport framework to the 2008 ozone NAAQS, EPA evaluated modeling 
projections for air-quality monitoring sites in 2017 and considered 
current (at the time) ozone monitoring data at these sites to identify 
receptors \10\ anticipated to have problems attaining or maintaining 
the 2008 ozone NAAQS. Next, EPA used air-quality modeling to assess 
contributions from upwind states to these downwind receptors and 
evaluated the contributions relative to a screening threshold of one 
percent (1%) of the NAAQS. States with contributions that equaled or 
exceeded the 1% threshold were identified as warranting further 
analysis for ``significant contribution to nonattainment'' or 
``interference with maintenance'' of the NAAQS. In the CSAPR Update, 
EPA found that Massachusetts did not contribute at or above the 1% 
threshold to any downwind nonattainment or maintenance receptor. See 81 
FR 74506. Therefore, EPA did not issue FIP requirements for sources in 
Massachusetts as part of CSAPR Update. See id. at 74553.
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    \10\ Within the CSAPR framework, the term ``receptor'' indicates 
a monitoring site. Under CSAPR Update, nonattainment receptors are 
downwind monitoring sites that are projected to have an average 
design value that exceed the NAAQS and that have a current monitored 
design value above the NAAQS, while maintenance receptors are 
downwind monitoring sites that are projected to have maximum design 
values that exceed the NAAQS.
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    On June 6, 2014, Massachusetts submitted most of its infrastructure 
SIP for the 2008 ozone NAAQS to EPA. On December 21, 2016, EPA fully 
approved most, and conditionally approved some portions, of that 
submittal. See 81 FR 93627. However, that submittal did not include the 
``good neighbor'' provisions of section 110(a)(2)(D)(i)(I). On February 
9, 2018, Massachusetts submitted a SIP revision to address this unmet 
SIP obligation for the 2008 ozone NAAQS. In today's action, we are 
proposing to approve that submittal.
    In its February 2018, submittal, the Commonwealth noted that the 
CSAPR Update states that the largest modeled contribution of emissions 
from Massachusetts to nonattainment and maintenances receptors are well 
below the threshold of 1% of the NAAQS. Massachusetts also pointed to 
the declining trend in ozone-precursor emissions that has occurred in 
the Commonwealth to support its view that Massachusetts is unlikely to 
cause future problems to downwind attainment or maintenance receptors. 
Moreover, we note that, in the CSAPR Update, EPA already ``determined 
that emissions from [Massachusetts] do not significantly contribute to 
nonattainment or interfere with maintenance of the 2008 ozone NAAQS in 
downwind states'' and that EPA ``need not require further emission 
reductions from sources in [Massachusetts] to address the good

[[Page 40347]]

neighbor provision as to the 2008 ozone NAAQS.'' 81 FR at 74506.
    In light of the above, we propose that Massachusetts has met its 
CAA Section 110(a)(2)(D)(i)(I) ``good neighbor'' SIP obligation for the 
2008 ozone NAAQS.

C. Background and Evaluation of the Massachusetts Transport SIP for the 
2015 Ozone Standard

    EPA has released several documents relevant to evaluating 
interstate transport with respect to the 2015 ozone NAAQS. First, on 
January 6, 2017, EPA published a notice of data availability (NODA) for 
preliminary interstate ozone-transport modeling with projected ozone 
design values for 2023.\11\ The year 2023 aligns with the expected 
attainment year for Moderate ozone nonattainment areas under the 2015 
ozone standard. On October 27, 2017, EPA issued a memorandum (2017 
memorandum) containing updated modeling data for 2023, with changes 
made in response to comments on the NODA.\12\ The 2017 memorandum also 
included data for the 2023 modeling year. Although it stated that the 
modeling may be useful for states for developing SIPs addressing ``good 
neighbor'' obligations for the 2008 ozone NAAQS, the 2017 memorandum 
did not address the 2015 ozone NAAQS.
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    \11\ 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).
    \12\ 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) 
(Oct. 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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    On March 27, 2018, EPA issued a memorandum (March 2018 memorandum) 
indicating that the same 2023 modeling data released in the 2017 
memorandum may also be useful for evaluating potential downwind air-
quality problems with respect to the 2015 ozone NAAQS (step 1 of the 
four-step framework).\13\ The March 2018 memorandum included 
contribution-modeling results to help states evaluate their impact on 
potential downwind air-quality problems (step 2 of the four-step 
framework). In August and October 2018, EPA issued two more memoranda 
that provided guidance for developing ``good neighbor'' SIPs for the 
2015 ozone NAAQS regarding (1) potential contribution thresholds that 
may be appropriate to apply in step 2 and (2) considerations for 
identifying downwind areas that may have problems maintaining the 
standard (i.e., prong 2) at step 1 of the framework.\14\
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    \13\ 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) 
(Mar. 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.
    \14\ 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 (Aug. 31, 2018) (``August 2018 memorandum''); 
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 (Oct. 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 described the updated photochemical and 
source-apportionment modeling used to project ambient ozone 
concentrations for 2023 and the state-by-state impacts on those 
concentrations. As described in the 2017 and March 2018 memoranda, 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 for the 2015 ozone 
NAAQS. The March 2018 memorandum presented design values calculated in 
two ways: (1) Following the EPA's historic ``3 x 3'' approach \15\ to 
evaluating all sites, and (2) following a modified approach for coastal 
monitoring sites in which ``overwater'' modeling data were not included 
in the calculation of future-year design values (known as the ``no 
water approach'').
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    \15\ See March 2018 memorandum, p. 4.
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    For identifying potential nonattainment and maintenance receptors 
in 2023, EPA applied the same approach as that used in the CSAPR 
Update. Specifically, EPA identified nonattainment receptors as those 
monitors with both measured values \16\ and projected 2023 average 
design values exceeding the NAAQS. The EPA identified maintenance 
receptors as those monitors with projected maximum design values 
exceeding the NAAQS. This included monitoring sites with measured 
values below the NAAQS, but with projected average and maximum design 
values above the NAAQS, and monitoring sites with projected average 
design values below the NAAQS, but with projected maximum design values 
above the NAAQS. Data for all monitoring sites projected to be 
nonattainment or maintenance receptors based on the updated 2023 
modeling is included in Attachment B of the March 2018 memorandum.
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    \16\ 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, EPA performed nationwide, state-level ozone source-
apportionment modeling to estimate the expected impact from each state 
to each nonattainment and maintenance receptor.\17\ For more 
information, 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 today's action.
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    \17\ 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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    As noted previously, on August 31, 2018, EPA issued a memorandum 
(the August 2018 memorandum) providing guidance concerning 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 1% 
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 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 1% of the 2015 ozone NAAQS. Accordingly, EPA indicated 
that it may be reasonable and appropriate for states to use a 1 ppb 
contribution threshold, as an alternative to the 1% threshold, at step 
2 of the four-step framework in developing their SIP revisions 
addressing the good neighbor provision for the 2015 ozone NAAQS.\18\
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    \18\ See August 2018 memorandum, p. 4.
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    Although the March 2018 memorandum presented information regarding 
EPA's latest analysis of ozone transport, 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, EPA noted that, in developing their SIPs, states 
have flexibility to

[[Page 40348]]

follow different analytical approaches than EPA if their chosen 
approach has adequate technical justification and is consistent with 
the requirements of the CAA.
    On September 27, 2018, Massachusetts submitted a SIP revision 
addressing the infrastructure SIP requirements of section 110(a)(2), 
including the section 110(a)(2)(D)(i)(I) interstate transport 
requirements for the 2015 ozone NAAQS.\19\ Massachusetts relied on the 
results of EPA's modeling for the 2015 ozone NAAQS (in the March 2018 
memorandum) to identify downwind nonattainment and maintenance 
receptors that may be impacted by emissions from sources in the 
Commonwealth. Based on Massachusetts' review of EPA's modeling 
assumptions, model performance evaluation, and the modifications made 
in response to public comments, the Commonwealth determined that EPA's 
future-year projections were appropriate for purposes of evaluating 
Massachusetts' impact on attainment and maintenance of the 2015 ozone 
NAAQS in other states. Thus, the Commonwealth concurred with EPA's 
photochemical modeling results that indicate Massachusetts' greatest 
impact on any potential downwind nonattainment or maintenance receptor 
would be 0.24 ppb.
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    \19\ As noted earlier, in this action, EPA is only addressing 
the requirements of section 110(a)(2)(D)(i)(I). EPA will address the 
remaining infrastructure requirements for the 2015 ozone NAAQS in a 
separate rulemaking(s).
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    Massachusetts compared these values to a screening threshold of 
0.70 ppb, representing 1% of the 2015 ozone NAAQS, and concluded that 
because none of the Commonwealth's impacts exceed this threshold, 
emissions from Massachusetts sources will not significantly contribute 
to nonattainment or interfere with maintenance of the 2015 ozone NAAQS 
in any other state.
    The March 2018 memorandum also provided contribution data regarding 
the impact of other states on the potential receptors. To evaluate the 
Commonwealth's 2015 ozone NAAQS interstate-transport SIP submission, 
EPA used the 1% threshold to conclude that the state's impact will not 
significantly contribute to nonattainment or interfere with maintenance 
of the NAAQS in any other state. EPA notes that, consistent with the 
August 2018 memorandum, it may be reasonable for states to use a 1-ppb 
contribution threshold as an alternative to a 1% threshold at step 2 of 
the four-step framework. However, for the reasons discussed below, it 
is unnecessary for EPA to determine the appropriateness of applying a 
1-ppb threshold for purposes of today's action.
    EPA's updated 2023 modeling discussed in the March 2018 memorandum 
indicates that Massachusetts' largest impact on any potential downwind 
nonattainment or maintenance receptor is 0.24 ppb at the Queens, New 
York, monitor. This value is less than 0.70 ppb (1% of the 2015 ozone 
NAAQS),\20\ and demonstrates that emissions from Massachusetts are not 
linked to any projected 2023 downwind nonattainment and maintenance 
receptors identified in the March 2018 memorandum. Therefore, EPA 
proposes to find that Massachusetts will not significantly contribute 
to nonattainment or interfere with maintenance of the 2015 ozone NAAQS 
in any other state.
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    \20\ Because none of Massachusetts' impacts exceed 0.70 ppb, 
they necessarily also do not exceed the 1ppb contribution threshold 
discussed in the August 2018 memorandum.
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III. Proposed Action

    EPA is proposing to approve Massachusetts' SIP revisions that were 
submitted to address prongs 1 and 2 of the interstate transport 
requirements for CAA section 110(a)(2)(D)(i)(I) for the 1997, 2008, and 
2015 ozone NAAQS. EPA is soliciting public comments on the issues 
discussed in this notice or on other relevant matters.\21\ These 
comments will be considered before taking final action. Interested 
parties may participate in the Federal rulemaking procedure by 
submitting written comments to this proposed rule by following the 
instructions listed in the ADDRESSES section of this Federal Register.
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    \21\ EPA is not reopening for comment final determinations made 
in CSAPR or in the CSAPR Update or the modeling conducted to support 
those rulemakings.
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IV. 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);
     Is not expected to be an Executive Order 13771 regulatory 
action because this action is not significant under Executive Order 
12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the 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, Incorporation by 
reference, Nitrogen dioxide, Ozone, Particulate matter, Volatile 
organic compounds.


[[Page 40349]]


    Dated: August 7, 2019.
Deborah Szaro,
Acting Regional Administrator, EPA Region 1.
[FR Doc. 2019-17406 Filed 8-13-19; 8:45 am]
 BILLING CODE 6560-50-P


