Document ID: EPA-R08-OAR-2018-0055-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Interstate Transport Prongs 1 and 2 for the 2012 Fine Particulate Matter (PM2.5) Standard for Colorado, Montana, North Dakota, South Dakota and Wyoming
Posted Date: 2018-05-09T04:00Z

[Federal Register Volume 83, Number 90 (Wednesday, May 9, 2018)]
[Proposed Rules]
[Pages 21226-21232]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-09880]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2018-0055; FRL-9977--44--Region 8]

Interstate Transport Prongs 1 and 2 for the 2012 Fine Particulate 
Matter (PM2.5) Standard for Colorado, Montana, North Dakota, 
South Dakota and Wyoming

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve portions of State Implementation Plan (SIP) submissions from 
Colorado, Montana, North Dakota, South Dakota and Wyoming addressing 
the Clean Air Act (CAA or Act) interstate transport SIP requirements 
for the 2012 annual Fine Particulate Matter (PM2.5) National 
Ambient Air Quality Standards (NAAQS). These submissions address the 
requirement that each SIP contain adequate provisions prohibiting air 
emissions that will have certain adverse air quality effects in other 
states. The EPA is proposing to approve portions of these 
infrastructure SIPs for the aforementioned states as containing 
adequate provisions to ensure that air emissions in the states will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 annual PM2.5 NAAQS in any other state.

DATES: Comments must be received on or before June 8, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No EPA-R08-
OAR-2018-0055 at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from www.regulations.gov. 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, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Adam Clark, Air Program, U.S. EPA 
Region 8, (303) 312-7104, [email protected].

SUPPLEMENTARY INFORMATION: 

I. Background

    On December 14, 2012, the EPA revised the primary annual 
PM2.5 NAAQS to 12.0 micrograms per cubic meter ([mu]g/m\3\). 
See 78 FR 3086 (January 15, 2013). An area meets the standard if the 
three-year average of its annual average PM2.5 concentration 
(at each monitoring site in the area) is less than or equal to 12.0 
[mu]g/m\3\. The CAA requires states to submit, within three years after 
promulgation of a new or revised standard, SIPs meeting the applicable 
``infrastructure'' elements of sections 110(a)(1) and (2). One of these 
applicable infrastructure elements, CAA section 110(a)(2)(D)(i), 
requires SIPs to contain ``good neighbor'' provisions to prohibit 
certain adverse air quality effects on neighboring states due to 
interstate transport of pollution.
    Section 110(a)(2)(D)(i) includes four distinct components, commonly 
referred to as ``prongs,'' that must be addressed in infrastructure SIP 
submissions. The first two prongs, which are codified in section 
110(a)(2)(D)(i)(I), are provisions that prohibit any source or other 
type of emissions activity in one state from contributing significantly 
to nonattainment of the NAAQS in another state (prong 1) and from 
interfering with maintenance of the NAAQS in another state (prong 2). 
The third and fourth prongs, which are codified in section 
110(a)(2)(D)(i)(II), are provisions that prohibit emissions activity in 
one state from interfering with measures required to prevent 
significant deterioration of air quality in another state (prong 3) or 
from interfering with measures to protect visibility in another state 
(prong 4).

[[Page 21227]]

    In this action, the EPA is proposing to approve the prong 1 and 
prong 2 portions of infrastructure SIP submissions submitted by: 
Colorado on December 1, 2015; Montana on December 17, 2015; North 
Dakota on August 23, 2015; South Dakota on January 25, 2016; and 
Wyoming on June 24, 2016, as containing adequate provisions to ensure 
that air emissions in these states will not significantly contribute to 
nonattainment or interfere with maintenance of the 2012 annual 
PM2.5 NAAQS in any other state. All other applicable 
infrastructure SIP requirements for these SIP submissions have been 
addressed in separate rulemakings.\1\
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    \1\ See 82 FR 39030, August 17, 2017 (Colorado); 81 FR 23180, 
April 20, 2016 (Montana); 82 FR 46681, October 6, 2017 (North 
Dakota); 82 FR 38832, August 16, 2017 (South Dakota); 82 FR 18992, 
April 25, 2017, and 82 FR 9142, February 3, 2017 (Wyoming).
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II. Relevant Factors To Evaluate 2012 PM[bdi2].[bdi5] 
Interstate Transport SIPs

    We review each state's submission to see how it evaluates the 
transport of air pollution to other states for a given air pollutant, 
the types of information the state used in its analysis, how that 
analysis compares with prior EPA rulemakings, modeling, and guidance, 
and the conclusions drawn by the state.
    The EPA has developed a consistent framework for addressing 
interstate transport with respect to the PM2.5 NAAQS. This 
framework includes the following four steps: (1) Identify downwind 
areas that are expected to have problems attaining or maintaining the 
NAAQS; (2) Identify which upwind states contribute to these air quality 
problems in amounts sufficient to warrant further review and analysis; 
(3) Identify any emissions reductions necessary to prevent an 
identified upwind state from significantly contributing to downwind 
nonattainment or interfering with downwind maintenance of the NAAQS; 
and (4) Adopt permanent and enforceable measures needed to achieve 
those emissions reductions.
    To help states identify the receptors expected to have problems 
attaining or maintaining the 2012 annual PM2.5 NAAQS, the 
EPA released a memorandum titled, ``Information on the Interstate 
Transport `Good Neighbor' Provision for the 2012 Fine Particulate 
Matter National Ambient Air Quality Standards under Clean Air Act 
Section 110(a)(2)(D)(i)(I)'' on March 17, 2016 (hereon ``2016 
Memo'').\2\ The 2016 Memo provides projected future year annual 
PM2.5 design values for monitors throughout the country 
based on quality assured and certified ambient monitoring data and 
recent air quality modeling and explains the methodology used to 
develop these projected design values. The 2016 Memo also describes how 
the projected values can be used to help determine which monitors 
should be further evaluated as potential receptors under step 1 of the 
interstate transport framework described above, and how to determine 
whether emissions from other states significantly contribute to 
nonattainment or interfere with maintenance of the 2012 annual 
PM2.5 NAAQS at these monitoring sites.
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    \2\ This memorandum is available in the docket and at https://www.epa.gov/sites/production/files/2016-08/documents/good-neighbor-memo_implementation.pdf.
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    To develop the projected values presented in the 2016 Memo, the EPA 
used the results of nationwide photochemical air quality modeling that 
it recently performed to support several ozone NAAQS-related 
rulemakings. Base year modeling was performed for 2011. Future year 
modeling was performed for 2017 to support the Cross-State Air 
Pollution Rule (CSAPR) Update for the 2008 Ozone NAAQS. See 81 FR 74504 
(October 26, 2016). Future year modeling was performed for 2025 to 
support the Regulatory Impact Assessment of the final 2015 Ozone 
NAAQS.\3\ In addition, and relevant to this proposed action on 
interstate transport SIPs for the 2012 annual PM2.5 NAAQS, 
the outputs from these model runs included hourly concentrations of 
PM2.5 that were used in conjunction with measured data to 
project annual average PM2.5 design values for 2017 and 
2025.
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    \3\ See 2015 ozone NAAQS RIA at: http://www3.epa.gov/ozonepollution/pdfs/20151001ria.pdf.
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    Areas that were designated as moderate PM2.5 
nonattainment areas for the 2012 annual PM2.5 NAAQS in 2014 
must attain the NAAQS by December 31, 2021, or as expeditiously as 
practicable. Since modeling results are only available for 2017 and 
2025, the 2016 Memo explains that one way to assess potential receptors 
for 2021\4\ is to assume that receptors projected to have average and/
or maximum design values above the NAAQS in both 2017 and 2025 are also 
likely to be either nonattainment or maintenance receptors in 2021. 
Similarly, the EPA stated that it may be reasonable to assume that 
receptors that are projected to attain the NAAQS in both 2017 and 2025 
are also likely to be attainment receptors in 2021. Where a potential 
receptor is projected to be nonattainment or maintenance in 2017, but 
projected to be attainment in 2025, further analysis of the emissions 
and modeling may be needed to make a further judgement regarding the 
receptor status in 2021.
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    \4\ Assessing downwind PM2.5 air quality problems 
based on estimates of air quality concentrations in a future year 
aligned with the relevant attainment deadline is consistent with the 
instructions from the United States Court of Appeals for the 
District of Columbia Circuit (D.C. Circuit) in North Carolina v. 
EPA, 531 F.3d 896, 911-12 (D.C. Cir. 2008), that upwind emission 
reductions should be harmonized, to the extent possible, with the 
attainment deadlines for downwind areas.
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    Based on this approach, the EPA identified 19 potential 
nonattainment and/or maintenance receptors. All of the 17 potential 
nonattainment receptors are located in California. One of the potential 
maintenance-only receptors is located in Shoshone County, Idaho, and 
the other potential maintenance-only receptor is located in Allegheny 
County, Pennsylvania.
    In the 2016 Memo, the EPA noted that because of data quality 
problems, nonattainment and maintenance projections were not done for 
all or portions of Florida, Illinois, Idaho, Tennessee and Kentucky. 
Data quality problems were since resolved for Tennessee, Kentucky and 
Florida, identifying no additional potential receptors, with those 
areas having design values below the 2012 annual PM2.5 NAAQS 
and expected to maintain the NAAQS due to downward emission trends for 
NOX and SO2 (www.epa.gov/air-trends/air-quality-design-values and www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data). Recent ambient data from 2015 and 2016 for 
Idaho and Illinois indicated that violations of the 2012 annual 
PM2.5 NAAQS in the areas with previous data quality issues 
are unlikely. Considering this information, the very low background 
concentrations recorded at IMPROVE monitoring site locations in Idaho, 
and the continuing downward trend of annual PM2.5 levels at 
monitors across Illinois, we propose that the Idaho and Illinois areas 
should not be considered receptors for purposes of the 2012 annual 
PM2.5 NAAQS.\5\
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    \5\ These data quality issues are addressed in more detail in 
the technical support documents (TSDs) for this rulemaking, which 
can be found in the docket.
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    After identifying potential receptors, the next step is to identify 
whether upwind states contribute to air pollution at each of the 
identified receptors in other states. In the 2016 Memo, the EPA did not 
calculate the portion of any downwind state's predicted 
PM2.5 concentrations that would result from emissions from 
individual states. Accordingly, the EPA will evaluate prong 1 and 2 
submissions for states using a weight of evidence analysis.

[[Page 21228]]

This analysis is based on a review of the state's submission and other 
available information, including air quality trends; topographical, 
geographical, and meteorological information; local emissions in 
downwind states and emissions from the upwind state; contribution 
modeling from prior interstate transport analyses; and existing and 
planned emission control measures in the state of interest. While none 
of these factors is by itself dispositive, together they may be used in 
weight of evidence analyses to determine whether the emissions from 
each of the five states that are the subject of this notice will 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 annual PM2.5 NAAQS at the identified receptors 
in the 2016 Memo.

III. States' Submissions and the EPA's Analysis

    In this section, we provide an overview of each state's 2012 annual 
PM2.5 transport analysis, as well as a summary of the EPA's 
evaluation of prongs 1 and 2 for each state. A detailed discussion of 
our evaluations can be found in the Technical Support Documents (TSDs) 
for this action, with separate TSDs for each of the five states. The 
TSDs can be accessed through www.regulations.gov (e-docket EPA-R08-OAR-
2018-0055).
    Colorado: Colorado concluded that it does not contribute 
significantly to nonattainment or interfere with maintenance of the 
2012 annual PM2.5 NAAQS in any other state for the following 
reasons: (1) Colorado has never violated the 2012 PM2.5 
NAAQS; (2) The nearest downwind nonattainment area is about 900 miles 
from Colorado's eastern border,\6\ and the nearest upwind nonattainment 
area is about 600 miles from Colorado's western border; and (3) 
Colorado has an EPA-approved Regional Haze State Implementation Plan 
that will result in substantial future reductions of PM2.5 
and its precursors.
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    \6\ Colorado was referring to the Floyd County, Indiana area. 
The EPA did not consider transport to this area as part of this 
action because no receptors in the area were projected as 
nonattainment or maintenance monitors in the 2016 Memo.
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    The EPA notes that, because Colorado's analysis focused on 
designated nonattainment areas, it does not independently address 
whether the SIP contains adequate provisions prohibiting emissions that 
will interfere with maintenance of the 2012 PM2.5 NAAQS in 
any other state. In remanding the Clean Air Interstate Rule (CAIR) to 
the EPA in North Carolina v. EPA, the D.C. Circuit explained that the 
regulating authority must give the ``interfere with maintenance'' 
clause of section 110(a)(2)(D)(i)(I) ``independent significance'' by 
evaluating the impact of upwind state emissions on downwind areas that, 
while currently in attainment, are at risk of future nonattainment, 
considering historic variability.\7\ While Colorado's submittal pre-
dates the 2016 Memo, which provided the states with information about 
potential maintenance-only receptors, Colorado was still required to 
evaluate the potential impact of its emissions on areas that are 
currently measuring clean data, but that may have issues maintaining 
that air quality, and Colorado did not do so.
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    \7\ 531 F.3d 896, 910-11 (D.C. Cir. 2008) (holding that the EPA 
must give ``independent significance'' to each prong of CAA section 
110(a)(2)(D)(i)(I)).
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    The EPA reviewed the information in Colorado's submittal, as well 
as the 2016 Memo and additional supplemental information for our 
evaluation, and we propose to come to the same conclusion as the state. 
This includes Colorado's conclusion that the state will not interfere 
with maintenance in downwind states, because we supplemented the 
state's analysis by identifying and assessing impacts on potential 
maintenance receptors. In our evaluation, we identified potential 
downwind nonattainment and maintenance receptors using the 2016 Memo. 
We then evaluated these receptors to determine whether Colorado 
emissions could significantly contribute to nonattainment or interfere 
with maintenance at them. Below, we provide an overview of our 
analysis. A more detailed evaluation of how the SIP revisions meet the 
requirements of CAA section 110(a)(2)(D)(i)(I) may be found in the 
Colorado TSD.
    With regard to the 17 California receptors, our analysis showed 
that elevated PM2.5 levels in California are driven 
primarily by local emissions.\8\ Additionally, Colorado's western 
border is more than 570 miles to the east and generally downwind of the 
California receptors, with several intervening mountain ranges which 
tend to impede interstate pollution transport. Finally, monitoring data 
demonstrate that the air in remote areas between Colorado and 
California is well below the level of the 2012 PM2.5 NAAQS. 
All of these factors indicate that emissions from Colorado will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at any California projected 
receptors.
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    \8\ See ``California: Imperial County, Los Angeles-South Coast 
Air Basin, Plumas County, San Joaquin Valley Area Designations for 
the 2012 Primary Annual PM2.5 National Ambient Air 
Quality Standard Technical Support Document'' in the docket for this 
action.
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    With regard to the Shoshone County, Idaho receptor, our analysis 
showed that elevated PM2.5 levels in the area are driven 
primarily by local emissions from wood burning in the wintertime.\9\ 
Additionally, Colorado is more than 550 miles to the southeast and 
downwind of this receptor. Finally, monitoring data indicate that the 
air in remote areas between Colorado and the Idaho receptor is well 
below the level of the 2012 PM2.5 NAAQS. All of these 
factors indicate that emissions from Colorado will not significantly 
contribute to nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS at the projected Shoshone County receptor.
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    \9\ See ``Idaho: West Silver Valley Nonattainment Area--2012 
Primary Annual PM2.5 National Ambient Air Quality 
Standard Technical Support Document'' in the docket for this action.
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    With regard to the Allegheny County, Pennsylvania receptor, our 
analysis included review of previous modeling data conducted for the 
EPA's 2011 CSAPR, which addressed the 1997 and 2006 PM2.5 
NAAQS.\10\ For the 2011 CSAPR, the EPA modeled contribution from states 
in the Eastern U.S. to air quality monitors (referred to as 
``receptors'') also located in the Eastern U.S.\11\ Therefore, the 2011 
CSAPR modeling did not project downwind contribution of emissions from 
Colorado, but projected contributions from states immediately east of 
Colorado, including Kansas. This modeling indicated that Kansas, a 
state located much closer to the Allegheny County receptor and with 
higher PM2.5 precursor emissions than Colorado,\12\ was 
modeled to be below 1% (the contribution level at which eastern states 
were considered ``linked'' to downwind receptors in the CSAPR and CSAPR 
Update rulemakings) of the 2012 annual PM2.5 NAAQS at all 
receptors in the eastern U.S., including the Allegheny County receptor. 
Additionally, the modeling information contained in EPA's 2016 Memo 
shows that the Allegheny County receptor is projected to both attain 
and maintain

[[Page 21229]]

the NAAQS by 2025. These factors, in addition to the very large 
distance (1,165 miles) from the Allegheny County receptor to the 
Colorado border, indicate that emissions from Colorado will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at the projected Allegheny County 
receptor.
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    \10\ See Table V.D-1 in the EPA's Cross-State Air Pollution Rule 
(CSAPR) (August 8, 2011), at 76 FR 48240.
    \11\ In these rules, ``Eastern'' states refer to all contiguous 
states east of the Rocky Mountains, specifically not including: 
Montana, Wyoming, Colorado and New Mexico.
    \12\ See Tables 7-1 and 7-2 in ``Emissions Inventory Final Rule 
Technical Support Document (TSD)'' for CSAPR, June 28, 2011, 
Document number EPA-HQ-OAR-2009-0491-4522 in www.regulations.gov.
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    Based on these analyses, the EPA is proposing to approve the SIP 
submittal as meeting the CAA section 110(a)(2)(D)(i)(I) requirement 
that Colorado emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS in any other state.
    Montana: Montana concluded that it does not contribute 
significantly to nonattainment or interfere with maintenance of the 
2012 annual PM2.5 NAAQS in any other state for the following 
reasons: (1) The one PM2.5 nonattainment area within the 
state, the Libby 1997 PM2.5 nonattainment area, monitors 
PM2.5 values which attain the 2012 PM2.5 NAAQS; 
(2) Elevated levels of PM2.5 in the state which can occur 
during the wintertime are highly dependent on low wind speed and 
meteorological ``inversions'' that lead to limited vertical mixing, 
resulting in neighborhood-scale impacts that are unlikely to contribute 
to elevated PM2.5 levels in other states; and (3) The 
evidence indicates that Montana does not contribute to elevated 
emissions at the only area designated nonattainment for the 2012 
PM2.5 NAAQS with close proximity to the state, the West 
Silver Valley in Shoshone County, Idaho. Montana cited the EPA's 
technical support document on the West Silver Valley, Idaho 
nonattainment area designation,\13\ which indicated that residential 
wood combustion within the West Silver Valley during wintertime periods 
of low wind speeds and low mixing height was the primary cause of the 
PM2.5 issues in that area. Montana also noted winds into the 
West Silver Valley tend to be westerly, and that the Bitterroot and 
Coeur D'Alene mountain ranges run along the western border of Montana 
between the state and the West Silver Valley nonattainment area. 
Montana asserted that all of these considerations combined made it 
unlikely that emissions from Montana sources will contribute 
significantly to nonattainment or interfere with maintenance in the 
West Silver Valley, Idaho area.
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    \13\ See ``Idaho: West Silver Valley Nonattainment Area- 2012 
Primary Annual PM2.5 National Ambient Air Quality 
Standard Technical Support Document'' in the docket for this action.
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    The EPA notes that, because Montana's analysis focused on 
designated nonattainment areas, it does not independently address 
whether the SIP contains adequate provisions prohibiting emissions that 
will interfere with maintenance of the 2012 PM2.5 NAAQS in 
any other state. While Montana's submittal pre-dates the 2016 Memo, 
which provided the states with information about potential maintenance-
only receptors, Montana was still required to evaluate the potential 
impact of its emissions on areas that are currently measuring clean 
data, but that may have issues maintaining that air quality, and 
Montana did not do so.
    The EPA reviewed the information in Montana's submittal, as well as 
the 2016 Memo and additional supplemental information for our 
evaluation, and we propose to come to the same conclusion as the state. 
This includes Montana's conclusion that the state will not interfere 
with maintenance in downwind states, because we supplemented the 
state's analysis by identifying and assessing impacts on potential 
maintenance receptors. In our evaluation, we identified potential 
downwind nonattainment and maintenance receptors using the 2016 Memo. 
We then evaluated these receptors to determine whether Montana 
emissions could significantly contribute to nonattainment or interfere 
with maintenance at them. Below, we provide an overview of our 
analysis. A more detailed evaluation of how the SIP revisions meet the 
requirements of CAA section 110(a)(2)(D)(i) may be found in the TSD.
    With regard to the Shoshone County, Idaho receptor, our analysis 
indicated that elevated PM2.5 levels in the area are driven 
primarily by local emissions from wood burning in the wintertime during 
inversion conditions, and therefore are not driven by transported 
emissions.\14\ Monitoring data also indicate that the air in remote 
areas in western Montana and throughout the region is well below the 
level of the 2012 PM2.5 NAAQS, especially during the winter 
months when PM2.5 levels at the Shoshone County receptor are 
highest.\15\ Additionally, the predominant wind direction in Shoshone 
County is from the west, while Montana is located to the east, making 
transport of emissions from Montana to this receptor unlikely. Finally, 
the intervening topography of the Bitterroot and Coeur D'Alene mountain 
ranges would impede interstate pollution transport. These factors, 
which are also discussed in Montana's analysis and further examined by 
the EPA in a TSD for this action,\16\ indicate that emissions from 
Montana will not significantly contribute to nonattainment or interfere 
with maintenance of the 2012 PM2.5 NAAQS at the projected 
Shoshone County receptor.
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    \14\ Id.
    \15\ See Id. at 13, as well as ``IMPROVE data 2013-2015,'' in 
the docket for this action.
    \16\ The TSD for the Montana portion of this rulemaking can be 
found in the docket for this action.
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    With regard to the 17 California receptors, our analysis showed 
that elevated PM2.5 levels in California are driven 
primarily by local emissions.\17\ Additionally, Montana is more than 
630 miles to the northeast and generally downwind of the California 
receptors, with several intervening mountain ranges which tend to 
impede interstate pollution transport. Finally, monitoring data 
demonstrate that the air in remote areas between Montana and California 
is well below the level of the 2012 PM2.5 NAAQS. All of 
these factors indicate that emissions from Montana will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at any California projected 
receptors.
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    \17\ See ``California: Imperial County, Los Angeles-South Coast 
Air Basin, Plumas County, San Joaquin Valley Area Designations for 
the 2012 Primary Annual PM2.5 National Ambient Air 
Quality Standard Technical Support Document'' in the docket for this 
action.
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    With regard to the Allegheny County, Pennsylvania receptor, our 
analysis included review of previous modeling data conducted for the 
EPA's 2011 CSAPR.\18\ The 2011 CSAPR modeling did not project downwind 
contribution of emissions from Montana, but projected contributions 
from states immediately east of Montana, including North Dakota. This 
modeling indicated that North Dakota, a state located much closer to 
the Allegheny County receptor and with higher PM2.5 
precursor emissions than Montana,\19\ was modeled to be below 1% of the 
2012 annual PM2.5 NAAQS at all receptors in the eastern 
U.S., including the Allegheny County receptor. Additionally, the 
modeling information contained in the EPA's 2016 Memo shows that the 
Allegheny County receptor is projected to both attain and

[[Page 21230]]

maintain the NAAQS by 2025. These factors, in addition to the very 
large distance (1,267 miles) from the Allegheny County receptor to 
Montana's eastern border, indicate that emissions from Montana will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at the projected Allegheny County 
receptor.
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    \18\ See Table V.D-1 in the EPA's Cross-State Air Pollution Rule 
(CSAPR) (August 8, 2011), at 76 FR 48240.
    \19\ See Tables 7-1 and 7-2 in ``Emissions Inventory Final Rule 
Technical Support Document (TSD)'' for CSAPR, June 28, 2011, 
Document number EPA-HQ-OAR-2009-0491-4522 in www.regulations.gov.
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    Based on our analyses, the EPA is proposing to approve the SIP 
submittal as meeting the CAA section 110(a)(2)(D)(i)(I) requirement 
that Montana emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS in any other state.
    North Dakota: North Dakota concluded that it does not contribute 
significantly to nonattainment or interfere with maintenance of the 
2012 annual PM2.5 NAAQS in any other state for the following 
reasons: (1) There are no PM2.5 nonattainment areas within 
North Dakota; (2) The nearest 2012 PM2.5 nonattainment area, 
in Shoshone County, Idaho, is roughly 660 miles west of the western 
border of North Dakota. Given that the three PM2.5 monitors 
in western North Dakota indicate very low annual PM2.5 
levels, and the wind in the western U.S. is generally westerly, any 
PM2.5 contribution from North Dakota to the nearest 
nonattainment area would be insignificant; (3) The modeling conducted 
for the EPA's CSAPR (August 8, 2011, 76 FR 48208) indicated that North 
Dakota sources have a maximum annual average contribution to any 
nonattainment area of .06 [mu]g/m\3\, and a maximum contribution of .04 
[mu]g/m\3\ to any maintenance receptor in the Eastern U.S.; (4) Annual 
PM2.5 monitor values throughout North Dakota are all well 
below the 2012 PM2.5 NAAQS; and (5) Direct and precursor 
emissions of PM2.5 have been steadily declining in North 
Dakota for years. Between 2004-2014, NOx emissions in the state 
decreased by 36%, SO2 emissions decreased by 64%, and 
primary particulate emissions from major point sources decreased by 
19%, with further anticipated reductions due to North Dakota's Regional 
Haze requirements.
    The EPA reviewed the information in North Dakota's submittal, as 
well as the 2016 Memo and additional supplemental information for our 
evaluation, and we propose to come to the same conclusion as the state. 
In our evaluation, we identified potential downwind nonattainment and 
maintenance receptors using the 2016 Memo. We then evaluated these 
receptors to determine whether North Dakota emissions could 
significantly contribute to nonattainment or interfere with maintenance 
at them. Below, we provide an overview of our analysis. A more detailed 
evaluation of how the SIP revisions meet the requirements of CAA 
section 110(a)(2)(D)(i) may be found in the North Dakota TSD.
    With regard to the 17 California receptors, our analysis showed 
that elevated PM2.5 levels in California are driven 
primarily by local emissions.\20\ Additionally, North Dakota is more 
than 1,030 miles to the east and generally downwind of the California 
receptors, with several intervening mountain ranges which tend to 
impede interstate pollution transport. Finally, monitoring data 
demonstrate that the air in remote areas between North Dakota and 
California is well below the level of the 2012 PM2.5 NAAQS. 
All of these factors indicate that emissions from North Dakota will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at any California projected 
receptors.
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    \20\ See ``California: Imperial County, Los Angeles-South Coast 
Air Basin, Plumas County, San Joaquin Valley Area Designations for 
the 2012 Primary Annual PM2.5 National Ambient Air 
Quality Standard Technical Support Document: in the docket for this 
action.
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    With regard to the Shoshone County, Idaho receptor, our analysis 
showed that elevated PM2.5 levels in the area are driven 
primarily by local emissions from wood burning in the wintertime.\21\ 
Additionally, North Dakota is more than 500 miles to the east and 
downwind of this receptor. Finally, monitoring data indicate that the 
air in remote areas between North Dakota and the Shoshone County 
receptor is well below the level of the 2012 PM2.5 NAAQS. 
All of these factors indicate that emissions from North Dakota will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at the projected Shoshone County 
receptor.
---------------------------------------------------------------------------

    \21\ See ``Idaho: West Silver Valley Nonattainment Area- 2012 
Primary Annual PM2.5 National Ambient Air Quality 
Standard Technical Support Document'' in the docket for this action.
---------------------------------------------------------------------------

    With regard to the Allegheny County, Pennsylvania receptor, our 
analysis included review of previous modeling data conducted for the 
EPA's 2011 CSAPR.\22\ As noted, this modeling projected North Dakota's 
impact at all receptors in the eastern U.S., including the Allegheny 
County receptor, and that impact was modeled to be well below 1% of the 
2012 annual PM2.5 NAAQS at all receptor locations.\23\ 
Additionally, the modeling information contained in EPA's 2016 Memo 
shows that the Allegheny County receptor is projected to both attain 
and maintain the NAAQS by 2025. These factors, in addition to the very 
large distance (925 miles) from the Allegheny County receptor to North 
Dakota's eastern border, indicate that emissions from North Dakota will 
not significantly contribute to nonattainment or interfere with 
maintenance of the 2012 PM2.5 NAAQS at the projected 
Allegheny County receptor.
---------------------------------------------------------------------------

    \22\ See Table V.D-1 in the EPA's Cross-State Air Pollution Rule 
(CSAPR) (August 8, 2011), at 76 FR 48240.
    \23\ Id.
---------------------------------------------------------------------------

    Based on these analyses, the EPA is proposing to approve the SIP 
submittal as meeting the CAA section 110(a)(2)(D)(i)(I) requirement 
that North Dakota emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS in any other state.
    South Dakota: South Dakota concluded that it does not contribute 
significantly to nonattainment or interfere with maintenance of the 
2012 annual PM2.5 NAAQS in any other state for the following 
reasons: (1) There are no 2012 PM2.5 nonattainment or 
maintenance areas within South Dakota or neighboring states; (2) 
Source-oriented PM2.5 emissions are low throughout South 
Dakota; (3) Existing programs in the South Dakota SIP will prevent new 
or modified sources from causing nonattainment in South Dakota or 
contributing significantly to nonattainment or maintenance with this 
NAAQS in neighboring states; and (4) South Dakota has a small 
population.
    The EPA notes that, because South Dakota's analysis focused on 
designated nonattainment areas, it does not independently address 
whether the SIP contains adequate provisions prohibiting emissions that 
will interfere with maintenance of the 2012 PM2.5 NAAQS in 
any other state. While South Dakota's submittal pre-dates the 2016 
Memo, which provided the states with information about potential 
maintenance-only receptors, South Dakota was still required to evaluate 
the potential impact of its emissions on areas that are currently 
measuring clean data, but that may have issues maintaining that air 
quality, and South Dakota did not do so.
    The EPA reviewed the information in South Dakota's submittal, as 
well as the 2016 Memo and additional supplemental information for our 
evaluation, and we propose to come to the same conclusion as the state. 
This includes South Dakota's conclusion that the state will not 
interfere with maintenance in downwind states, because we supplemented 
the state's analysis by identifying and assessing impacts on potential 
maintenance

[[Page 21231]]

receptors. In our evaluation, we identified potential downwind 
nonattainment and maintenance receptors using the 2016 Memo. We then 
evaluated these receptors to determine whether South Dakota emissions 
could significantly contribute to nonattainment or interfere with 
maintenance at them. Below, we provide an overview of our analysis. A 
more detailed evaluation of how the SIP revisions meet the requirements 
of CAA section 110(a)(2)(D)(i) may be found in the South Dakota TSD.
    With regard to the 17 California receptors, our analysis showed 
that elevated PM2.5 levels in California are driven 
primarily by local emissions.\24\ Additionally, South Dakota is more 
than 937 miles to the northeast and generally downwind of the 
California receptors. Finally, monitoring data demonstrate that the air 
in remote areas between South Dakota and California is well below the 
level of the 2012 PM2.5 NAAQS. All of these factors indicate 
that emissions from South Dakota will not significantly contribute to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS at any California projected receptors.
---------------------------------------------------------------------------

    \24\ See ``California: Imperial County, Los Angeles-South Coast 
Air Basin, Plumas County, San Joaquin Valley Area Designations for 
the 2012 Primary Annual PM2.5 National Ambient Air 
Quality Standard Technical Support Document'' in the docket for this 
action.
---------------------------------------------------------------------------

    With regard to the Shoshone County, Idaho receptor, our analysis 
showed that elevated PM2.5 levels in the area are driven 
primarily by local emissions from wood burning in the wintertime.\25\ 
Additionally, South Dakota is more than 600 miles to the east and 
downwind of this receptor. Finally, monitoring data indicate that the 
air in remote areas between South Dakota and the Idaho receptor is well 
below the level of the 2012 PM2.5 NAAQS. All of these 
factors indicate that emissions from South Dakota will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at the projected Shoshone County 
receptor.
---------------------------------------------------------------------------

    \25\ See ``Idaho: West Silver Valley Nonattainment Area--2012 
Primary Annual PM2.5 National Ambient Air Quality 
Standard Technical Support Document'' in the docket for this action.
---------------------------------------------------------------------------

    With regard to the Allegheny County, Pennsylvania receptor, our 
analysis included review of previous modeling data conducted for the 
EPA's 2011 CSAPR.\26\ This modeling projected South Dakota's impact at 
all receptors in the eastern U.S., including the Allegheny County 
receptor, and that impact was modeled to be well below 1% of the 2012 
annual PM2.5 NAAQS at all receptor locations.\27\ 
Additionally, the modeling information contained in the EPA's 2016 Memo 
shows that the Allegheny County receptor is projected to both attain 
and maintain the NAAQS by 2025. These factors, in addition to the very 
large distance (880 miles) from the Allegheny County receptor to South 
Dakota's eastern border, indicate that emissions from South Dakota will 
not significantly contribute to nonattainment or interfere with 
maintenance of the 2012 PM2.5 NAAQS at the projected 
Allegheny County receptor.
---------------------------------------------------------------------------

    \26\ See Table V.D-1 in the EPA's Cross-State Air Pollution Rule 
(CSAPR) (August 8, 2011), at 76 FR 48240.
    \27\ Id.
---------------------------------------------------------------------------

    Based on these analyses, the EPA is proposing to approve the SIP 
submittal as meeting the CAA section 110(a)(2)(D)(i)(I) requirement 
that South Dakota emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS in any other state.
    Wyoming: Wyoming concluded that it does not contribute 
significantly to nonattainment or interfere with maintenance of the 
2012 annual PM2.5 NAAQS in any other state for the following 
reasons: (1) There are no PM2.5 nonattainment areas within 
Wyoming, and all PM2.5 monitors in the state indicate levels 
well below the NAAQS in spite of certain maximum values being 
influenced by wildfires; (2) There are no 2012 PM2.5 
nonattainment areas in states bordering Wyoming apart from Idaho; and 
(3) The evidence indicates that Wyoming does not contribute to elevated 
emissions at the only area designated nonattainment for the 2012 
PM2.5 NAAQS with close proximity to the state, the West 
Silver Valley in Shoshone County, Idaho. This nonattainment area is 
over 300 miles from the nearest border of Wyoming, and wind roses 
within Wyoming show that winds primarily blow west-to-east, and do not 
favor southeast-to-northwest transport needed for Wyoming emissions to 
impact this nonattainment area. The monitored PM2.5 values 
in the Wyoming counties nearest the West Silver Valley, Idaho 
nonattainment area are well below the NAAQS. Wyoming also cited the 
EPA's technical support document on the West Silver Valley, Idaho, 
nonattainment area designation,\28\ which indicated that residential 
wood combustion and prescribed burning within the West Silver Valley 
were the primary causes of PM2.5 issues in that area. 
Wyoming also stated that the Beaverhead, Lemhi, Teton and Gallatin 
mountain ranges also inhibited westward transport between Wyoming and 
the West Silver Valley, Idaho nonattainment area. Wyoming asserted that 
all of these considerations combined made it reasonable to conclude 
that emissions from Wyoming sources are not significantly contributing 
to nonattainment in the West Silver Valley, Idaho area.
---------------------------------------------------------------------------

    \28\ See ``Idaho: West Silver Valley Nonattainment Area--2012 
Primary Annual PM2.5 National Ambient Air Quality 
Standard Technical Support Document'' in the docket for this action.
---------------------------------------------------------------------------

    The EPA notes that, because Wyoming's analysis focused on 
designated nonattainment areas, it does not independently address 
whether the SIP contains adequate provisions prohibiting emissions that 
will interfere with maintenance of the 2012 PM2.5 NAAQS in 
any other state. Each state is required to evaluate the potential 
impact of its emissions on areas that are currently measuring clean 
data, but that may have issues maintaining that air quality, and 
Wyoming did not do so.
    The EPA reviewed the information in Wyoming's submittal, as well as 
the 2016 Memo and additional supplemental information for our 
evaluation, and we propose to come to the same conclusion as the state. 
This includes Wyoming's conclusion that the state will not interfere 
with maintenance in downwind states, because we supplemented the 
state's analysis by identifying and assessing impacts on potential 
maintenance receptors. In our evaluation, we identified potential 
downwind nonattainment and maintenance receptors using the 2016 Memo. 
We then evaluated these receptors to determine whether Wyoming 
emissions could significantly contribute to nonattainment or interfere 
with maintenance at them. Below, we provide an overview of our 
analysis. A more detailed evaluation of how the SIP revisions meet the 
requirements of CAA section 110(a)(2)(D)(i) may be found in the Wyoming 
TSD.
    With regard to the Shoshone County, Idaho receptor, our analysis 
showed that elevated PM2.5 levels in the area are driven 
primarily by local emissions from wood burning in the wintertime during 
inversion conditions, and therefore are not driven by transported 
emissions.\29\ Additionally, monitoring data indicate that the air in 
remote areas between Wyoming and the Idaho receptor is well below the 
level of the 2012 PM2.5 NAAQS. These factors indicate that 
emissions from Wyoming will not significantly contribute to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS

[[Page 21232]]

at the projected Shoshone County receptor.
---------------------------------------------------------------------------

    \29\ Id.
---------------------------------------------------------------------------

    With regard to the 17 California receptors, our analysis showed 
that elevated PM2.5 levels in California are driven 
primarily by local emissions.\30\ Additionally, Wyoming is more than 
548 miles to the east and generally downwind of the California 
receptors, with several intervening mountain ranges which tend to 
impede interstate pollution transport. Finally, monitoring data 
demonstrate that the air in remote areas between Wyoming and California 
is well below the level of the 2012 PM2.5 NAAQS. All of 
these factors indicate that emissions from Wyoming will not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2012 PM2.5 NAAQS at any California projected 
receptors.
---------------------------------------------------------------------------

    \30\ See ``California: Imperial County, Los Angeles-South Coast 
Air Basin, Plumas County, San Joaquin Valley Area Designations for 
the 2012 Primary Annual PM2.5 National Ambient Air 
Quality Standard Technical Support Document'' in the docket for this 
action.
---------------------------------------------------------------------------

    With regard to the Allegheny County, Pennsylvania receptor, our 
analysis included review of previous modeling data conducted for the 
EPA's 2011 CSAPR.\31\ The 2011 CSAPR modeling did not project 
contribution of emissions from Wyoming, but projected contributions 
from states immediately east of Wyoming, including Nebraska. This 
modeling indicated that Nebraska, a state located much closer to the 
Allegheny County receptor and with higher PM2.5 precursor 
emissions than Wyoming,\32\ was modeled to be below 1% of the 2012 
annual PM2.5 NAAQS at all receptors in the eastern U.S., 
including the Allegheny County receptor. Additionally, the modeling 
information contained in the EPA's 2016 Memo shows that the Allegheny 
County receptor is projected to both attain and maintain the NAAQS by 
2025. These factors, in addition to the very large distance (1,260 
miles) from the Allegheny County receptor to Wyoming's eastern border, 
indicate that emissions from Wyoming will not significantly contribute 
to nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS at the projected Allegheny County receptor.
---------------------------------------------------------------------------

    \31\ See Table V.D-1 in the EPA's Cross-State Air Pollution Rule 
(CSAPR) (August 8, 2011), at 76 FR 48240.
    \32\ See Tables 7-1 and 7-2 in ``Emissions Inventory Final Rule 
Technical Support Document (TSD)'' for CSAPR, June 28, 2011, 
Document number EPA-HQ-OAR-2009-0491-4522 in www.regulations.gov.
---------------------------------------------------------------------------

    Based on these analyses, the EPA is proposing to approve the SIP 
submittal as meeting the CAA section 110(a)(2)(D)(i)(I) requirement 
that Wyoming emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS in any other state.

IV. Proposed Action

    The EPA is proposing to approve the following submittals as meeting 
the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) 
for the 2012 PM2.5 NAAQS: Colorado's December 1, 2015 
submittal; Montana's December 17, 2015 submittal; North Dakota's August 
23, 2015 submittal; South Dakota's January 25, 2016 submittal; and 
Wyoming's June 24, 2016 submittal. The EPA is proposing this approval 
based on our review of the information and analysis provided by each 
state, as well as additional relevant information, which indicates that 
in-state air emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2012 
PM2.5 NAAQS in any other state. This action is being taken 
under section 110 of the CAA.

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 CAA. Accordingly, 
these proposed actions merely approve state law as meeting federal 
requirements and do not impose additional requirements beyond those 
imposed by state law. For that reason, these proposed actions:
     Are not significant regulatory actions subject to review 
by the Office of Management and Budget under Executive Order 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Are not Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory actions because SIP approvals are exempted under 
Executive Order 12866;
     do not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     are 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.);
     do 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);
     do not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     are not economically significant regulatory actions based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     are not significant regulatory actions subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     are not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     do 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).
    In addition, these SIPs are not 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 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, Particulate 
matter, Reporting and recordkeeping requirements, Sulfur dioxide, 
Volatile organic compounds.

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

    Dated: May 4, 2018.
Douglas Benevento,
Regional Administrator, Region 8.
[FR Doc. 2018-09880 Filed 5-8-18; 8:45 am]
 BILLING CODE 6560-50-P