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[Federal Register Volume 81, Number 44 (Monday, March 7, 2016)]
[Proposed Rules]
[Pages 11727-11734]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-04900]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2015-0205; FRL-9943-27-Region 8]

Designation of Areas for Air Quality Planning Purposes; 
Redesignation Request and Associated Maintenance Plan for Billings, MT 
2010 SO2 Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: On December 14, 2015, the State of Montana submitted a request 
for the Environmental Protection Agency (EPA) to redesignate the 
Billings, Montana, 2010 sulfur dioxide (SO2) National 
Ambient Air Quality Standard (NAAQS) nonattainment area to attainment 
and to approve a State Implementation Plan (SIP) revision containing a 
maintenance plan for the area. In response to this submittal, the EPA 
is proposing to take the following actions: Determine that the Billings 
SO2 nonattainment area is attaining the 2010 SO2 
primary NAAQS; approve Montana's plan for maintaining attainment of the 
2010 SO2 primary NAAQS in the area; and redesignate the 
Billings SO2 nonattainment area to attainment for the 2010 
SO2 primary NAAQS.

DATES: Comments must be received on or before April 6, 2016.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2015-0205, at http://www.regulations.gov Web site. Follow the 
online instructions for submitting comments. Once submitted, comments 
cannot be edited or removed from regulations.gov. The EPA may publish 
any comment received to its public docket. Do not 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. 
Environmental Protection Agency, Region 8, Mailcode 8P-AR, 1595 
Wynkoop, Denver, Colorado 80202-1129, (303) 312-7104, 
clark.adam@epa.gov.

SUPPLEMENTARY INFORMATION:

I. General Information

What should I consider as I prepare my comments for EPA?

    1. Submitting Confidential Business Information (CBI). Do not 
submit CBI to the EPA through www.regulations.gov or email. Clearly 
mark the part or all of the information that you claim to be CBI. For 
CBI information in a disk or CD ROM that you mail to the EPA, mark the 
outside of the disk or CD ROM as CBI and then identify electronically 
within the disk or CD ROM the specific information that is claimed as 
CBI. In addition to one complete version of the comment that includes 
information claimed as CBI, a copy of the comment that does not contain 
the information claimed as CBI must be submitted for inclusion in the 
public docket. Information so marked will not be disclosed except in 
accordance with procedures set forth in 40 CFR part 2.
    2. Tips for Preparing Your Comments. When submitting comments, 
remember to:
     Identify the rulemaking by docket number and other 
identifying information (subject heading, Federal Register date and 
page number).
     Follow directions--The agency may ask you to respond to 
specific questions or organize comments by referencing a Code of 
Federal Regulations (CFR) part or section number.
     Explain why you agree or disagree; suggest alternatives 
and substitute language for your requested changes.
     Describe any assumptions and provide any technical 
information and/or data that you used.
     If you estimate potential costs or burdens, explain how 
you arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
     Provide specific examples to illustrate your concerns and 
suggest alternatives.

[[Page 11728]]

     Explain your views as clearly as possible, avoiding the 
use of profanity or personal threats.
     Make sure to submit your comments by the comment period 
deadline identified.

II. What is the background for the EPA's proposed actions?

    On June 2, 2010, the EPA revised the primary SO2 NAAQS, 
establishing a new 1-hour SO2 standard of 75 parts per 
billion (ppb). See 75 FR 35520 (June 2, 2010). Under the EPA's 
regulations at 40 CFR part 50, the 2010 1-hour SO2 NAAQS is 
met at a monitoring site when the 3-year average of the annual 99th 
percentile of 1-hour daily maximum concentrations is less than or equal 
to 75 ppb (based on the rounding convention in 40 CFR part 50, appendix 
T). See 40 CFR 50.17. Ambient air quality monitoring data for the 3-
year period must meet a data completeness requirement. A year meets 
data completeness requirements when all 4 quarters are complete, and a 
quarter is complete when at least 75 percent of the sampling days for 
each quarter have complete data. A sampling day has complete data if 75 
percent of the hourly concentration values, including state-flagged 
data affected by exceptional events which have been approved for 
exclusion by the Administrator, are reported.\1\
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    \1\ 40 CFR part 50, appendix T, section 3(b).
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    Upon promulgation of a new or revised NAAQS, the CAA requires the 
EPA to designate as nonattainment any area that does not meet (or that 
contributes to ambient air quality in a nearby area that does not meet) 
the NAAQS.\2\ At the time the EPA conducted the initial round of 
designations for the 2010 1-hour SO2 primary NAAQS,\3\ 
Billings contained an SO2 monitor (Coburn Road) which 
registered violations of the standard based on the three most recent 
years of complete, quality assured, and certified ambient air quality 
data. In a letter to the EPA, Montana Governor Brian Schweitzer 
requested that all 56 counties in Montana be designated as attainment 
or unclassifiable. The EPA responded to Montana's initial designations 
request in a February 6, 2013 letter in which the EPA disagreed with 
Montana's request to classify Yellowstone County (which includes 
Billings) as unclassifiable for the 2010 1-hour SO2 standard 
and presented the case that all of Yellowstone County should be 
designated as nonattainment. In an April 3, 2013 letter to the EPA, 
Montana reiterated its request that Yellowstone County be designated 
unclassifiable, but requested an alternative nonattainment area 
boundary consisting of only a small portion of Billings if the EPA 
determined that a nonattainment designation was appropriate. The EPA 
agreed with the State's technical rationale for reducing the 
nonattainment area to a small portion of Billings which included only 
one source of SO2: The PPL Corette Power Plant.\4\ The EPA 
found that Montana's technical analysis demonstrated that the PPL 
Corette plant was the key contributor to the 2010 SO2 NAAQS 
violations at the Coburn Road monitor. The EPA, therefore, designated 
the area recommended by Montana as nonattainment for the 2010 
SO2 NAAQS on August 5, 2013, (effective October 4, 2013) 
using 2009-2011 ambient air quality data, leaving the remaining portion 
of Billings and Yellowstone County undesignated and subject to future 
analysis and designation. See 78 FR 47191 (August 5, 2013). This 
nonattainment designation established an attainment date five years 
after the October 4, 2013, effective date for areas classified as 
nonattainment for the 2010 1-hour SO2 NAAQS.\5\ Therefore, 
the Billings SO2 nonattainment area's attainment date is 
October 4, 2018. The Montana Department of Environmental Quality (MDEQ) 
was also required to submit an attainment SIP to EPA within 18 months 
following the October 4, 2013 effective date of designation, or by 
April 6, 2015.\6\
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    \2\ CAA section 107(d)(1)(A)(i).
    \3\ The EPA finalized nonattainment designations for 29 areas of 
the U.S. that contained SO2 monitors violating the NAAQS 
on August 5, 2013 (78 FR 47191, 47205), and took no designation-
related action on the rest of the country. The EPA was placed under 
a binding schedule for designation of the remaining portions of the 
U.S. for the 2010 1-hour SO2 NAAQS on March 2, 2015. See, 
Sierra Club, et al. v. McCarthy, Case No. 13-cv-03953-SI (N.D. Cal., 
March 2, 2015).
    \4\ Montana's recommended alternative boundary, now the Billings 
2010 SO2 Nonattainment Area, can be found in the Billings 
Redesignation Request at 13.
    \5\ CAA section 192.
    \6\ CAA section 191.
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    On January 16, 2015, MDEQ submitted a request for the EPA to 
determine that the Billings SO2 nonattainment area has 
attained the 2010 SO2 NAAQS per the EPA's ``clean data 
policy'' (Billings 2010 SO2 Clean Data Request).\7\ The 
clean data policy represents the EPA's interpretation that certain 
planning-related requirements of part D of the Act, such as the 
attainment demonstration, reasonably available control measures (RACM), 
and reasonable further progress (RFP), are suspended for areas that are 
in fact attaining the NAAQS. The clean data policy will be explained 
further in Section IV of this proposed rulemaking. A determination of 
attainment, or clean data determination, does not constitute a formal 
redesignation to attainment. If EPA subsequently determines that an 
area is no longer attaining the standard, those requirements that were 
suspended by the clean data determination are once again due.
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    \7\ The Billings 2010 SO2 Clean Data Request is 
available in the docket for this action.
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    On April 10, 2015, James Parker of PPL Montana sent a letter to Ed 
Warner of MDEQ notifying him that the PPL Corette Plant was officially 
retired on March 18, 2015, and had consumed its last coal on March 3, 
2015. On May 13, 2015, Gordon Criswell of PPL Montana sent a letter to 
MDEQ requesting a revocation of the Montana Air Quality Permit (MAQP) 
#2953-00 and Title V Operating Permit #OP2953-08. On May 21, 2015, 
David Klemp of MDEQ sent a letter to Mr. Criswell informing him that 
MDEQ was revoking both permits, as PPL had requested, effective 
immediately.
    On December 14, 2015, the State submitted to the EPA a request for 
redesignation of the Billings 2010 SO2 nonattainment area to 
attainment and a SIP revision containing a maintenance plan for the 
area.

III. What are the criteria for redesignation?

    The CAA provides the requirements for redesignating a nonattainment 
area to attainment. Specifically, section 107(d)(3)(E) of the CAA 
allows for redesignation of a nonattainment area provided that: (1) The 
Administrator determines that the area has attained the applicable 
NAAQS; (2) the Administrator has fully approved the applicable 
implementation plan for the area under section 110(k); (3) the 
Administrator determines that the improvement in air quality is due to 
permanent and enforceable reductions in emissions resulting from 
implementation of the applicable SIP and applicable federal air 
pollutant control regulations and other permanent and enforceable 
reductions; (4) the Administrator has fully approved a maintenance plan 
for the area as meeting the requirements of section 175A; and (5) the 
state containing such area has met all requirements applicable to the 
area for purposes of redesignation under section 110 and part D of the 
CAA.
    On April 16, 1992, the EPA provided guidance on redesignation in 
the General Preamble for the Implementation of title I of the CAA 
Amendments of 1990 (57 FR 13498), and supplemented this guidance on

[[Page 11729]]

April 28, 1992 (57 FR 18070). The EPA has provided further guidance on 
processing redesignation requests in several guidance documents. For 
the purposes of this action, the EPA will be referencing two of these 
documents: (1) The September 4, 1992 Memorandum from John Calcagni 
titled ``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' (hereafter referred to as the ``Calcagni Memo''); and (2) 
The April 23, 2014 Memorandum from Stephen D. Page titled ``Guidance 
for 1-Hour SO2 Nonattainment Area SIP Submissions,'' 
(hereafter referred to as ``2010 SO2 NAA Guidance'').

IV. What is EPA's analysis of the request?

    EPA's evaluation of Montana's redesignation request and maintenance 
plan was based on consideration of the five redesignation criteria 
provided under CAA section 107(d)(3)(E).

Criteria (1)--The Billings SO2 Nonattainment Area Has Attained the 2010 
1-Hour SO2 NAAQS

    For redesignating a nonattainment area to attainment, the CAA 
requires the EPA to determine that the area has attained the applicable 
NAAQS (CAA section 107(d)(3)(E)(i)). The two primary methods for 
evaluating ambient air quality impacted by SO2 emissions are 
through dispersion modeling and air quality monitoring. For 
SO2, an area may in some circumstances be considered to be 
attaining the 2010 1-hour SO2 NAAQS if it meets the NAAQS as 
determined in accordance with 40 CFR 50.17 and Appendix T of part 50, 
based on three complete, consecutive calendar years of quality-assured 
air quality monitoring data. To attain the NAAQS based on monitoring, 
the 3-year average of the annual 99th percentile (fourth highest value) 
of 1-hour daily maximum concentrations measured at each monitor within 
an area must be less than or equal to 75 ppb. The data must be 
collected and quality-assured in accordance with 40 CFR part 58 and 
recorded in the EPA Air Quality System (AQS). The EPA's determination 
of attainment can be based on monitoring data alone, without the need 
for dispersion modeling analyses, if the air agency provides an 
analysis demonstrating that the monitor(s) for the affected area is 
located in the area of maximum ambient concentration of 
SO2.\8\
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    \8\ See 2010 SO2 NAA Guidance, at 62.
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    In this action, the EPA is determining that the Billings 
SO2 nonattainment area is attaining the 2010 1-hour 
SO2 NAAQS. The EPA reviewed SO2 monitoring data 
from the lone monitoring station inside the Billings SO2 
nonattainment area, the Coburn Road station. The Coburn Road monitor 
data have been quality-assured, are recorded in AQS, and indicate that 
the area is attaining the 2010 1-hour SO2 NAAQS. The fourth-
highest 1-hour SO2 values at the Coburn Road monitor for the 
3-year averages of these values (i.e., design values), are summarized 
in Table 1, below.

                                Table 1--Coburn Road Monitored SO2 Concentrations
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                                                                                                      2012-2014
                                                              2012          2013          2014      Design value
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Annual 99th Percentile..................................           70            48            93            70
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    As shown, the 3-year design value for 2012-2014 at the Coburn Road 
monitor meets the 2010 SO2 NAAQS. Further, the EPA expects 
the SO2 emissions at this monitor to decrease significantly 
following the shutdown of the PPL Corette facility. Since the facility 
last operated on March 3, 2015, the values at the Coburn Road monitor 
have not exceeded 19 ppb SO2. This trend is anticipated to 
be permanent, as the State indicated in its analysis that 
SO2 emissions have since 2010 consistently decreased to 
levels well below the NAAQS during times when PPL Corette was not 
operating.\9\
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    \9\ Billings Redesignation Request at 8-12.
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    As part of Montana's redesignation request, the State submitted 
information to support a showing that the Coburn Road monitor was sited 
in the area of maximum ambient SO2 concentration within the 
Billings SO2 nonattainment area in accordance with the 2010 
SO2 NAA Guidance. This showing included data from historical 
monitors near the Coburn Road monitor which consistently showed lower 
values than those at Coburn Road. The EPA has reviewed Montana's 
information regarding this showing, but finds that it is no longer 
applicable to the current SO2 emissions mix in the Billings 
SO2 nonattainment area because the sole SO2 
source in the area (PPL Corette) has shut down. The EPA does not find 
it necessary to require the State to conduct new modeling or 
exploratory monitoring as recommended by EPA's May 2013 Draft 
Monitoring Technical Assistance Document (TAD)\10\ to determine the 
point of maximum concentration in the nonattainment area because the 
source of concern in the area has shut down and been dismantled, 
resulting in SO2 concentrations well below the standard.
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    \10\ On page 58 of the 2010 SO2 NAA Guidance, EPA 
recommends that air agencies follow the Draft ``SO2 NAAQS 
Designations Source-Oriented Monitoring Technical Assistance 
Document,'' Office of Air Quality Planning and Standards, Air 
Quality Assessment Division. Although this 2010 SO2 NAA 
Guidance references the Draft monitoring TAD with regard to 
reviewing clean data determinations, the EPA also considers the TAD 
recommendations applicable to attainment demonstrations.
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    In this action, the EPA is proposing to determine that the Billings 
SO2 nonattainment area is attaining the 2010 1-hour 
SO2 NAAQS, and therefore meets the requirements of CAA 
section 107(d)(3)(E)(i). If the 3-year design value exceeds the NAAQS 
prior to the EPA taking action in response to the State's request, the 
EPA will not take final action to approve the redesignation 
request.\11\ As discussed in more detail below, Montana has committed 
to continue monitoring in this area in accordance with 40 CFR part 58.
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    \11\ See 2010 SO2 NAA Guidance, at 56.
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    As noted, Montana separately submitted to the EPA a request for a 
determination of clean data for the Billings SO2 
nonattainment area on January 16, 2015. The clean data policy 
represents the EPA's interpretation that certain requirements of part D 
of title I of the Act are suspended for areas that are currently 
attaining the NAAQS. The requirements that are suspended in an area 
attaining the standard include the requirements to submit an 
``attainment SIP'' that provides for: Attainment of the NAAQS; 
implementation of all RACM; RFP; and implementation of contingency 
measures for failure to meet deadlines for RFP and attainment. In the 
2010 SO2 NAA guidance, the EPA

[[Page 11730]]

explained our intention to apply the EPA's clean data policy to the 
2010 SO2 primary NAAQS.\12\ Because EPA's analysis in 
determining whether an area has attained under the clean data policy is 
the same as its analysis under the first redesignation criterion, EPA 
is also here proposing that the Billings SO2 nonattainment 
area qualifies for a determination of attainment under the clean data 
policy, based on the 2012-2014 monitoring data from the Coburn Road 
monitor. In the event that EPA does not finalize the proposed 
redesignation, EPA may choose to separately finalize the clean data 
determination, thereby suspending Montana's obligation to submit the 
attainment planning-related requirements for the area for as long as 
the area continues to attain the standard. As with its analysis that 
the area has attained under the redesignation requirements, for 
purposes of the clean data determination, the EPA is not requiring 
Montana to demonstrate that the monitor is located in the area of 
maximum concentration in accordance with the 2010 SO2 NAA 
Guidance due to the unique circumstances associated with the PPL 
Corette shutdown.\13\
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    \12\ Id. at 52.
    \13\ Id. at 58.
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Criteria (2)--Montana Has a Fully Approved SIP Under Section 110(k); 
and Criteria (5)--Montana Has Met All Applicable Requirements Under 
Section 110 and Part D of Title I of the CAA

    For redesignating a nonattainment area to attainment under a NAAQS, 
the CAA requires the EPA to determine that the state has met all 
applicable requirements for that NAAQS under section 110 and part D of 
title I of the CAA (CAA section 107(d)(3)(E)(v)) and that the state has 
a fully approved SIP under section 110(k) for that NAAQS for the area 
(CAA section 107(d)(3)(E)(ii)). The EPA proposes to find that Montana 
has met all applicable SIP requirements for the Billings SO2 
nonattainment area for the 2010 SO2 NAAQS under section 110 
of the CAA (general SIP requirements) for purposes of redesignation. 
Additionally, the EPA proposes to find that the Montana SIP satisfies 
the criterion that it meets applicable SIP requirements for purposes of 
redesignation under part D of title I of the CAA in accordance with 
section 107(d)(3)(E)(v). Further, the EPA proposes to determine that 
the SIP is fully approved with respect to all requirements applicable 
for the 2010 SO2 NAAQS for purposes of redesignation in 
accordance with section 107(d)(3)(E)(ii). In making these 
determinations, the EPA ascertained which requirements are applicable 
to the Billings SO2 nonattainment area and, if applicable, 
that they are fully approved under section 110(k).
a. The Billings SO2 Nonattainment Area Has Met All 
Applicable Requirements Under Section 110 and Part D of the CAA
    General SIP requirements. General SIP elements and requirements are 
delineated in section 110(a)(2) of title I, part A of the CAA. These 
requirements include, but are not limited to, the following: Submittal 
of a SIP that has been adopted by the state after reasonable public 
notice and hearing; provisions for establishment and operation of 
appropriate procedures needed to monitor ambient air quality; 
implementation of a source permit program; provisions for the 
implementation of part C requirements (Prevention of Significant 
Deterioration (PSD)) and provisions for the implementation of part D 
requirements (New Source Review (NSR) permit programs); provisions for 
air pollution modeling; and provisions for public and local agency 
participation in planning and emission control rule development.
    Section 110(a)(2)(D) requires that SIPs contain certain measures to 
prevent sources in a state from significantly contributing to air 
quality problems in another state. To implement this provision, the EPA 
has required certain states to establish programs to address the 
interstate transport of air pollutants. The section 110(a)(2)(D) 
requirements for a state are not linked with a particular nonattainment 
area's designation and classification in that state. The EPA believes 
that the requirements linked with a particular nonattainment area's 
designation and classifications are the relevant measures to evaluate 
in reviewing a redesignation request. The transport SIP submittal 
requirements, where applicable, continue to apply to a state regardless 
of the designation of any one particular area in the state. Thus, the 
EPA does not believe that the CAA's interstate transport requirements 
should be construed to be applicable requirements for purposes of 
redesignation.
    In addition, the EPA believes other section 110 elements that are 
neither connected with nonattainment plan submissions nor linked with 
an area's attainment status are applicable requirements for purposes of 
redesignation. The area will still be subject to these requirements 
after the area is redesignated. The section 110 and part D requirements 
which are linked with a particular area's designation and 
classification are the relevant measures to evaluate in reviewing a 
redesignation request. This approach is consistent with the EPA's 
existing policy on applicability (i.e., for redesignations) of 
conformity and oxygenated fuels requirements, as well as with section 
184 ozone transport requirements. See Reading, Pennsylvania, proposed 
and final rulemakings (61 FR 53174-53176, October 10, 1996), (62 FR 
24826, May 7, 2008); Cleveland-Akron-Loraine, Ohio, final rulemaking 
(61 FR 20458, May 7,1996); and Tampa, Florida, final rulemaking at (60 
FR 62748, December 7, 1995). See also the discussion on this issue in 
the Cincinnati, Ohio, redesignation (65 FR 37890, June 19, 2000), and 
in the Pittsburgh, Pennsylvania, redesignation (66 FR 50399, October 
19, 2001).
    Title I, Part D, applicable SIP requirements. Section 172(c) of the 
CAA sets forth the basic requirements of attainment plans for 
nonattainment areas that are required to submit them pursuant to 
section 172(b). Subpart 5 of part D, which includes section 191 and 192 
of the CAA, establishes requirements for SO2, nitrogen 
dioxide and lead nonattainment areas. A thorough discussion of the 
requirements contained in sections 172(c) can be found in the General 
Preamble for Implementation of Title I (57 FR 13498).
    Subpart 5 Section 172 Requirements. Section 172(c)(1) requires the 
plans for all nonattainment areas to provide for the implementation of 
all RACM as expeditiously as practicable and to provide for attainment 
of the NAAQS. The EPA interprets this requirement to impose a duty on 
all nonattainment areas to consider all available control measures and 
to adopt and implement such measures as are reasonably available for 
implementation in each area as components of the area's attainment 
demonstration. Under section 172, states with nonattainment areas must 
submit plans providing for timely attainment and meeting a variety of 
other requirements.
    The EPA's longstanding interpretation of the nonattainment planning 
requirements of section 172 is that once an area is attaining the 
NAAQS, those requirements are not ``applicable'' for purposes of CAA 
section 107(d)(3)(E)(ii) and therefore need not be approved into the 
SIP before the EPA can redesignate the area. In the 1992 General 
Preamble for Implementation of Title I, the EPA set forth its 
interpretation of applicable requirements for purposes of evaluating 
redesignation requests when an area is attaining a standard. See 57 FR 
13498,

[[Page 11731]]

13564 (April 16, 1992). The EPA noted that the requirements for RFP and 
other measures designed to provide for attainment do not apply in 
evaluating redesignation requests because those nonattainment planning 
requirements ``have no meaning'' for an area that has already attained 
the standard. Id. This interpretation was also set forth in the 
Calcagni Memo. The EPA's understanding of section 172 also forms the 
basis of its Clean Data Policy, which was articulated with regard to 
SO2 in the 2010 SO2 NAA Guidance, and suspends a 
state's obligation to submit most of the attainment planning 
requirements that would otherwise apply, including an attainment 
demonstration and planning SIPs to provide for RFP, RACM, and 
contingency measures under section 172(c)(9). Courts have upheld the 
EPA's interpretation of section 172(c)(1) for ``reasonably available'' 
control measures and control technology as meaning only those controls 
that advance attainment, which precludes the need to require additional 
measures where an area is already attaining. NRDC v. EPA, 571 F.3d 
1245, 1252 (D.C. Cir. 2009); Sierra Club v. EPA, 294 F.3d 155, 162 
(D.C. Cir. 2002); Sierra Club v. EPA, 314 F.3d 735, 744 (5th Cir. 
2002); Sierra Club v. EPA, 375 F.3d 537 (7th Cir. 2004). But see Sierra 
Club v. EPA, 793 F.3d 656 (6th Cir. 2015).
    Therefore, because attainment has been reached in the Billings 
SO2 nonattainment area, no additional measures are needed to 
provide for attainment, and section 172(c)(1) requirements for an 
attainment demonstration and RACM are not part of the ``applicable 
implementation plan'' required to have been approved prior to 
redesignation per CAA section 107(d)(3)(E)(ii). The other section 172 
requirements that are designed to help an area achieve attainment--the 
section 172(c)(2) requirement that nonattainment plans contain 
provisions promoting reasonable further progress, the requirement to 
submit the section 172(c)(9) contingency measures, and the section 
172(c)(6) requirement for the SIP to contain control measures necessary 
to provide for attainment of the NAAQS--are also not required to be 
approved as part of the ``applicable implementation plan'' for purposes 
of satisfying CAA section 107(d)(3)(E)(ii).
    Section 172(c)(3) requires submission and approval of a 
comprehensive, accurate, and current inventory of actual emissions. The 
requirement for an emission inventory can be satisfied by meeting the 
inventory requirements of the maintenance plan.\14\ MDEQ submitted an 
emissions inventory as part of the maintenance plan for the Billings 
SO2 nonattainment area, and this inventory will be discussed 
further in the maintenance plan portion of this proposed action.
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    \14\ Calcagni Memo at 6.
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    Section 172(c)(4) requires the identification and quantification of 
allowable emissions for major new and modified stationary sources to be 
allowed in an area, and section 172(c)(5) requires source permits for 
the construction and operation of new and modified major stationary 
sources anywhere in the nonattainment area. The EPA has determined 
that, since PSD requirements will apply after redesignation, areas 
being redesignated need not comply with the requirement that a NSR 
program be approved prior to redesignation, provided that the area 
demonstrates maintenance of the NAAQS without part D NSR. A more 
detailed rationale for this view is described in a memorandum from Mary 
Nichols, Assistant Administrator for Air and Radiation, dated October 
14, 1994, entitled ``Part D New Source Review Requirements for Areas 
Requesting Redesignation to Attainment.'' MDEQ has demonstrated that 
the Billings SO2 nonattainment area will be able to maintain 
the NAAQS without part D NSR in effect, and therefore Montana need not 
have fully approved part D NSR programs prior to approval of the 
redesignation request. Montana's PSD program will become effective in 
the Billings SO2 nonattainment area upon redesignation to 
attainment.
    Section 172(c)(7) requires the SIP to meet the applicable 
provisions of section 110(a)(2). As noted above, the EPA believes the 
Montana SIP meets the requirements of section 110(a)(2) applicable for 
purposes of redesignation.
    Section 176 Conformity Requirements. Section 176(c) of the CAA 
requires states to establish criteria and procedures to ensure that 
federally supported or funded projects conform to the air quality 
planning goals in the applicable SIP. The requirement to determine 
conformity applies to transportation plans, programs, and projects that 
are developed, funded, or approved under title 23 of the United States 
Code (U.S.C.) and the Federal Transit Act (transportation conformity) 
as well as to all other federally supported or funded projects (general 
conformity). State transportation conformity SIP revisions must be 
consistent with federal conformity regulations relating to 
consultation, enforcement, and enforceability that the EPA promulgated 
pursuant to its authority under the CAA.
    Montana has an approved general conformity SIP for the Billings 
area. See 67 FR 62392 (October 7, 2002). Moreover, the EPA interprets 
the conformity SIP requirements as not applying for purposes of 
evaluating a redesignation request under section 107(d) because, like 
other requirements listed above, state conformity rules are still 
required after redesignation and federal conformity rules apply where 
state rules have not been approved. See Wall v. EPA, 265 F.3d 426 (6th 
Cir. 2001) (upholding this interpretation); see also 60 FR 62748 
(December 7, 1995) (redesignation of Tampa, Florida).
    For these reasons, the EPA proposes to find that Montana has 
satisfied all applicable requirements for purposes of redesignation of 
the Billings SO2 nonattainment area under section 110 and 
part D of title I of the CAA.
b. The Billings SO2 Nonattainment Area Has a Fully Approved 
Applicable SIP Under Section 110(k) of the CAA
    The EPA has fully approved the applicable Montana SIP for the 
Billings Area under section 110(k) of the CAA for all requirements 
applicable for purposes of redesignation. As indicated above, the EPA 
believes that the section 110 elements that are neither connected with 
nonattainment plan submissions nor linked to an area's nonattainment 
status are not applicable requirements for purposes of redesignation. 
The EPA has approved all part D requirements applicable under the 2010 
SO2 NAAQS, as identified above, for purposes of this 
redesignation.

Criteria (3)--The Air Quality Improvement in the Billings SO2 
Nonattainment Area Is Due to Permanent and Enforceable Reductions in 
Emissions

    For redesignating a nonattainment area to attainment, the CAA 
requires the EPA to determine that the air quality improvement in the 
area is due to permanent and enforceable reductions in emissions 
resulting from implementation of the SIP, applicable federal air 
pollution control regulations, and other permanent and enforceable 
reductions (CAA section 107(d)(3)(E)(iii)). The EPA proposes to find 
that Montana has demonstrated that the observed air quality improvement 
in the Billings SO2 nonattainment area is due to permanent 
and enforceable reductions in emissions. Specifically, the EPA 
considers the shutdown of the PPL Corette Plant, identified as the key

[[Page 11732]]

contributor to the SO2 NAAQS violations at the Coburn Road 
monitor,\15\ to be both permanent and enforceable. The EPA notes that 
the Corette facility was still operating (though not continuously) \16\ 
during the 2012-2014 period during which the 2010 SO2 NAAQS 
was attained in the Billings nonattainment area. Given the well-
established correlation of much lower SO2 emissions at the 
Coburn Road monitor during periods when Corette has not operated, EPA 
anticipates that the SO2 NAAQS will only attain by a greater 
margin following the facility's shutdown. As stated in the Calcagni 
Memo, ``Emission reductions from source shutdowns can be considered 
permanent and enforceable to the extent that those shutdowns have been 
reflected in the SIP and all applicable permits have been modified 
accordingly.'' \17\ MDEQ revoked PPL's Title V (operating) and NSR 
permits for the Corette facility.\18\ Further, the PPL Corette facility 
has been dismantled, making its future operation impossible and thus 
displaying the permanence of the emissions reductions in the 
nonattainment area. Any new sources that may come into being within the 
area would be required to demonstrate that their new SO2 
emissions would not interfere with attainment and maintenance of the 
2010 SO2 NAAQS. Therefore, the EPA is proposing to find that 
the air quality improvement in the Billings SO2 
nonattainment area is due to permanent and enforceable reductions in 
emissions.
---------------------------------------------------------------------------

    \15\ See EPA's final Technical Support Document (TSD) for the 
Billings SO2 Nonattainment Area, in the docket for EPA's 
initial round of 2010 SO2 designations at EPA-HQ-OAR-
2012-0233-0318.
    \16\ The Corette facility did not operate for several 
consecutive months in both 2012 and 2014.
    \17\ Calcagni Memo at 10.
    \18\ Permit revocation letters are included in the docket for 
this action.
---------------------------------------------------------------------------

Criteria (4)--The Billings SO2 Nonattainment Area Has a Fully Approved 
Maintenance Plan Pursuant to Section 175A of the CAA

    To redesignate a nonattainment area to attainment, the CAA requires 
the EPA to determine that the area has a fully approved maintenance 
plan pursuant to section 175A of the CAA (CAA section 
107(d)(3)(E)(iv)). In conjunction with its request to redesignate the 
Billings SO2 nonattainment area to attainment for the 2010 
1-hour SO2 NAAQS, MDEQ submitted a SIP revision to provide 
for the maintenance of the 2010 1-hour SO2 NAAQS for at 
least 10 years after the effective date of redesignation to attainment. 
The EPA is proposing to find that this maintenance plan for the area 
meets the requirements for approval under section 175A of the CAA.
a. What is required in a maintenance plan?
    CAA section 175A sets forth the elements of a maintenance plan for 
areas seeking redesignation from nonattainment to attainment. Under 
section 175A, the plan must demonstrate continued attainment of the 
applicable NAAQS for at least 10 years after the Administrator approves 
a redesignation to attainment. Eight years after the redesignation, the 
state must submit a revised maintenance plan demonstrating that 
attainment will continue to be maintained for the 10 years following 
the initial 10-year period. To address the possibility of future NAAQS 
violations, the maintenance plan must contain contingency measures as 
the EPA deems necessary to assure prompt correction of any future 2010 
1-hour SO2 violations. The Calcagni Memo provides further 
guidance on the content of a maintenance plan, explaining that a 
maintenance plan should address five requirements: The attainment 
emissions inventory, maintenance demonstration, monitoring, 
verification of continued attainment, and a contingency plan. As is 
discussed more fully below, the EPA is proposing to determine that 
Montana's maintenance plan includes all the necessary components and is 
thus proposing to approve it as a revision to the Montana SIP.
b. Attainment Emissions Inventory
    As part of a state's maintenance plan for a 2010 SO2 
nonattainment area, the air agency should develop an attainment 
inventory to identify the level of emissions in the affected area which 
is sufficient to attain and maintain the SO2 NAAQS.\19\ 
Montana selected 2014 as the base year (i.e., attainment emissions 
inventory year) for developing an emissions inventory for 
SO2 in the nonattainment area through 2024. In 2014, the 
final full calendar year in which PPL Corette was permitted to operate 
prior to the March 2015 shutdown, the facility emitted 1,433 tons of 
SO2.\20\
---------------------------------------------------------------------------

    \19\ See 2010 SO2 NAA Guidance, at 66.
    \20\ PPL Corette did not operate for nearly five months during 
2014.
---------------------------------------------------------------------------

    In 2014, the Coburn Road monitor reported exceedances of the 2010 
SO2 NAAQS on eight different days, giving the monitor a 99th 
percentile (4th highest 1-hour daily maximum concentration) of 93 ppb. 
Regardless, the 2014 emissions level of 1,433 tons of SO2 is 
the lowest level of any year in the attaining 2012 to 2014 period, 
making it the most conservative option for the purposes of ensuring 
future maintenance of the NAAQS (see Table 2). The EPA has therefore 
determined that this is a level sufficient to attain the 2010 1-hour 
SO2 NAAQS, and is proposing to find that the attainment 
inventory submitted as part of Montana's maintenance plan meets the 
``Attainment Emissions Inventory'' requirement.

      Table 2--Annual SO2 Emissions in Billings Nonattainment Area
------------------------------------------------------------------------
             Year                   2012          2013          2014
------------------------------------------------------------------------
Annual SO2 Emissions (tons)...        1,884         2,247         1,433
------------------------------------------------------------------------

    The EPA notes that the permanent shutdown of PPL Corette has left 
the Billings SO2 nonattainment area with no sources of 
SO2, and the maintenance plan for the area contains an 
emissions inventory (in the ``Maintenance Demonstration'' section) 
which projects a level of zero SO2 emissions in the 
nonattainment area for each year from 2016 through 2024. The EPA 
therefore does not anticipate emissions activity in the 2010 
SO2 nonattainment area that will approach 1,433 tons of 
SO2.
c. Maintenance Demonstration
    An air agency may generally demonstrate maintenance of the NAAQS by 
either showing that future emissions of SO2 will not exceed 
the level of the attainment inventory, or by modeling to show that the 
future mix of sources and emission rates will not cause a violation of 
the NAAQS.\21\ Montana has demonstrated maintenance by showing that 
future year emissions

[[Page 11733]]

(through ``out year'' 2024) of SO2 in the maintenance area 
are expected to remain at zero following the PPL Corette shutdown. The 
State's projected emissions inventory \22\ has been reproduced as Table 
3, below:
---------------------------------------------------------------------------

    \21\ See 2010 SO2 NAA Guidance at 67.
    \22\ The State's emissions inventory projection is listed as 
Figure 3.2 in the Billings SO2 Redesignation Request, at 
23.

                                       Table 3--Billings SO2 Nonattainment Area SO2 Projected Emissions Inventory
--------------------------------------------------------------------------------------------------------------------------------------------------------
                              Year                                 2014    2015    2016    2017    2018    2019    2020    2021    2022    2023    2024
--------------------------------------------------------------------------------------------------------------------------------------------------------
Annual SO2 Emissions (tons).....................................   1433     460       0       0       0       0       0       0       0       0       0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The EPA considers the inventory projection of zero emissions 
sufficient to attain and maintain the SO2 NAAQS. The EPA is 
therefore also proposing to find that the State's ``Maintenance 
Demonstration'' requirement is met based on this projected emissions 
inventory.
d. Monitoring Network
    Montana has committed to continue operating the Coburn Road monitor 
at its current location in the Billings SO2 nonattainment 
area. The State also committed to operating the monitor in accordance 
with the requirements of 40 CFR part 58, and have thus addressed the 
requirement for monitoring. The EPA approved Montana's monitoring plan 
on January 13, 2015. The EPA is proposing to find that Montana's 
maintenance plan meets the ``Monitoring Network'' requirement.
e. Verification of Continued Attainment
    Each air agency should ensure that it has the legal authority to 
implement and enforce all measures necessary to attain and maintain the 
2010 SO2 NAAQS. The air agency's submittal should indicate 
how it will track the progress of the maintenance plan for the area 
either through air quality monitoring or modeling.\23\
---------------------------------------------------------------------------

    \23\ 2010 SO2 Guidance at 67-68.
---------------------------------------------------------------------------

    The State of Montana has the legal authority to enforce and 
implement the maintenance plan for the Billings 2010 SO2 
nonattainment area. This includes the authority to adopt, implement, 
and enforce any subsequent emissions control contingency measures 
determined to be necessary to correct future SO2 attainment 
problems.\24\ As noted, the State will track the progress of the 
maintenance plan by continuing to operate the Coburn Road monitor. For 
these reasons, the EPA is proposing to find that Montana's maintenance 
plan meets the ``Verification of Continued Attainment'' requirement.
---------------------------------------------------------------------------

    \24\ EPA last determined that Montana's SIP was sufficient to 
meet the requirements of 110(a)(2)(E)(i) of the CAA on July 30, 2013 
(78 FR 45864).
---------------------------------------------------------------------------

f. Contingency Measures in the Maintenance Plan
    Section 175A of the CAA requires that a maintenance plan include 
such contingency measures as the EPA deems necessary to assure that the 
state will promptly correct a violation of the NAAQS that occurs after 
redesignation. The maintenance plan should identify the contingency 
measures to be adopted, a schedule and procedure for adoption and 
implementation, and a time limit for action by the state. A state 
should also identify specific indicators to be used to determine when 
the contingency measures need to be implemented. The maintenance plan 
must also include a requirement that a state will implement all 
measures with respect to control of the pollutant that were contained 
in the SIP before redesignation of the area to attainment in accordance 
with section 175A(d).
    The contingency plan includes a triggering mechanism to determine 
when contingency measures are needed and a process of developing and 
implementing appropriate control measures. The State listed two types 
of triggers of its contingency plan. The first, a ``warning level 
response,'' will be triggered by a 99th percentile of 1-hour daily 
maximum SO2 values greater than 65 ppb in a single calendar 
year. The second, an ``action level response,'' is triggered when such 
a value exceeds 70 ppb in a single calendar year.
    If the warning level response is triggered, the State must conduct 
a study to determine whether the SO2 values near the level 
of the 2010 SO2 NAAQS (75 ppb) are the result of a trend, 
and if so, what control measures are necessary to reverse that trend. 
The implementation of the control measures stemming from a warning 
level response will take place no later than 18 months after the end of 
the calendar year in which a determination requiring control measures 
was made. If the action level response is triggered and is not found to 
be due to an exceptional event as defined at 40 CFR part 50.1(j), the 
State will work with the entity or entities believed to be responsible 
for the high levels of SO2 to evaluate control measures 
necessary to ensure future attainment of the NAAQS. Montana must submit 
to the EPA its analysis demonstrating that the proposed control 
measures are adequate to ensure continued maintenance of the 2010 
SO2 NAAQS in the area or to return the area to attainment of 
the NAAQS. The implementation of the control measures stemming from an 
action level response will take place no later than 18 months after the 
end of the calendar year in which the action level response was 
prompted. Montana noted that, since the only source in the 
nonattainment area has shut down, it is not possible at this time to 
develop specific contingency measures until the cause of the elevated 
concentrations is known. The EPA is proposing to find that Montana's 
maintenance plan meets the ``Contingency Measures'' requirement.
    The EPA has concluded that the maintenance plan adequately 
addresses the five basic components of a maintenance plan: The 
attainment emissions inventory, maintenance demonstration, monitoring, 
verification of continued attainment, and a contingency plan. 
Therefore, the EPA proposes to find that the maintenance plan SIP 
revision submitted by Montana for the Billings 2010 SO2 
nonattainment area meets the requirements of section 175A of the CAA 
and is approvable.

V. What are the actions the EPA is proposing to take?

    The EPA is proposing to take the following four separate but 
related actions: (1) Determine that the Billings SO2 
nonattainment area is attaining the 2010 1-hour SO2 NAAQS; 
(2) Approve Montana's plan for maintaining the 2010 1-hour 
SO2 NAAQS (maintenance plan); (3) Redesignate the Billings 
SO2 nonattainment area to attainment for the 2010 1-hour 
SO2 NAAQS; and (4) determine that the Billings 
SO2 nonattainment area has clean monitoring data. Section IV 
of this notice provides a discussion of each of these proposed actions.
    The EPA proposes to determine that the Billings SO2 
nonattainment area has attained the 2010 1-hour SO2 standard 
by the October 4, 2018, required attainment date. This determination is 
based on complete, quality-assured, and

[[Page 11734]]

certified monitoring data for the 2012-2014 monitoring period. The EPA 
is also proposing to approve the maintenance plan under the 2010 NAAQS 
for the Billings SO2 nonattainment area into the Montana SIP 
(under CAA section 175A). The maintenance plan demonstrates that the 
area will continue to maintain the 2010 1-hour SO2 NAAQS, 
and includes a process to develop contingency measures to remedy any 
future violations of the 2010 1-hour SO2 NAAQS and 
procedures for evaluation of potential violations.
    Additionally, the EPA is proposing to determine that the Billings 
SO2 nonattainment area has met the criteria under CAA 
section 107(d)(3)(E) for redesignation from nonattainment to attainment 
for the 2010 1-hour SO2 NAAQS. On this basis, the EPA is 
proposing to approve Montana's redesignation request for the area. 
Final approval of Montana's redesignation request would change the 
legal designation of the portion of Yellowstone County designated 
nonattainment at 40 CFR part 81.327 to attainment for the 2010 1-hour 
SO2 NAAQS.
    The EPA is also proposing to determine that the Billings 
SO2 nonattainment area has attaining monitoring data for the 
2010 SO2 primary NAAQS based on the most recent complete 
three-year period (2012-2014) design value period that meets the clean 
data policy. As noted elsewhere, in the event that EPA does not 
finalize the proposed redesignation, EPA may choose to separately 
finalize the clean data determination, thereby suspending the 
attainment planning-related requirements for the area.
    In this action, the EPA is not proposing to take any action on the 
Billings/Laurel SO2 area that was the subject of a SIP Call 
(67 FR 22168, May 2, 2002) and for which EPA promulgated a FIP (77 FR 
21418, April 21, 2008) under the prior 24-hour SO2 primary 
NAAQS and the still-current SO2 secondary NAAQS. EPA is also 
not proposing any action to revoke the prior (1971) SO2 
primary NAAQS in either the 2010 Billings SO2 nonattainment 
area or the larger Billings/Laurel area addressed by the May 2, 2002 
SIP Call.

VI. Incorporation by Reference

    In this rule, the EPA is proposing to include in a final EPA rule 
regulatory text that includes incorporation by reference. In accordance 
with the requirements of 1 CFR 51.5, the EPA is proposing to 
incorporate by reference the Billings SO2 Redesignation and 
Maintenance Plan for action which are identified within this notice of 
proposed rulemaking. The EPA has made, and will continue to make, these 
documents generally available electronically through 
www.regulations.gov and/or in hard copy at the appropriate EPA office 
(see the ADDRESSES section of this rule's preamble for more 
information).

VII. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan under section 107(d)(3)(E) 
are actions that affect the status of a geographical area and do not 
impose any additional regulatory requirements on sources beyond those 
imposed by state law. A redesignation to attainment does not in and of 
itself create any new requirements, but rather results in the 
applicability of requirements contained in the CAA for areas that have 
been redesignated to attainment. Moreover, the Administrator is 
required to approve a SIP submission that complies with the provisions 
of the Act and applicable Federal regulations. See 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 CAA. 
Accordingly, these proposed actions merely propose to approve state law 
as meeting Federal requirements and do not impose additional 
requirements beyond those imposed by state law. For this reason, these 
proposed actions:
     Are not significant regulatory actions 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);
     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 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 does not apply on any Indian reservation land 
or in any other area where the EPA or an Indian tribe has demonstrated 
that a tribe has jurisdiction. In those areas of Indian country, the 
proposed rule does not have tribal implications and will not impose 
substantial direct costs on tribal governments or preempt tribal law as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Incorporation by reference, Intergovernmental relations, Lead, Nitrogen 
dioxide, Ozone, Particulate matter, Reporting and recordkeeping 
requirements, Sulfur oxides, Volatile organic compounds.

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

    Dated: February 23, 2016.
Richard D. Buhl,
Acting Regional Administrator, Region 8.
[FR Doc. 2016-04900 Filed 3-4-16; 8:45 am]
 BILLING CODE 6560-50-P
```