[Federal Register Volume 82, Number 170 (Tuesday, September 5, 2017)]
[Proposed Rules]
[Pages 41903-41908]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-18423]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 81

[EPA-HQ-OAR-2017-0003; FRL-9967-11-OAR]


EPA Responses to Certain State Designation Recommendations for 
the 2010 Sulfur Dioxide Primary National Ambient Air Quality Standard: 
Notification of Availability and Public Comment Period

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notification of availability and public comment period.

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SUMMARY: Notice is hereby given that the Environmental Protection 
Agency (EPA) has posted on our public electronic docket and Internet 
Web site responses to certain state designation recommendations for the 
2010 Sulfur Dioxide (SO2) Primary National Ambient Air 
Quality Standard (NAAQS). These responses include our intended 
designations for the affected areas. The EPA invites the public to 
review and provide input on our intended designations during the 
comment period specified in the DATES section. The EPA sent our 
responses directly to the states on or about August 22, 2017. The EPA 
intends to make final designation determinations for the areas of the 
country addressed by these responses no later than December 31, 2017.

DATES: Comments must be received on or before October 5, 2017. Please 
refer to SUPPLEMENTARY INFORMATION for additional information on the 
comment period.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2017-0003, at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from regulations.gov. The EPA may publish any 
comment received to our 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 https://www2.epa.gov/dockets/commenting-epa-dockets.
    The public may inspect the recommendations from the states and 
territories, our recent letters notifying the affected states, 
territories, and tribes of our intended designations, and area-specific 
technical support information at the following locations:

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            Regional offices                          States
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Dave Conroy, Chief, Air Programs         Connecticut, Maine,
 Branch, EPA New England, 1 Congress      Massachusetts, New Hampshire,
 Street, Suite 1100, Boston, MA 02114-    Rhode Island, and Vermont.
 2023, (617) 918-1661.
Richard Ruvo, Chief, Air Programs        New Jersey, New York, Puerto
 Branch, EPA Region II, 290 Broadway,     Rico, and Virgin Islands.
 25th Floor, New York, NY 10007-1866,
 (212) 637-4014.
Cynthia H. Stahl, Acting Associate       Delaware, District of Columbia,
 Director, Office of Air Program          Maryland, Pennsylvania,
 Planning, EPA Region III, 1650 Arch      Virginia, and West Virginia.
 Street, Philadelphia, PA 19103-2187,
 (215) 814-2180.
R. Scott Davis, Chief, Air Planning      Alabama, Florida, Georgia,
 Branch, EPA Region IV, Sam Nunn          Kentucky, Mississippi, North
 Atlanta Federal Center, 61 Forsyth       Carolina, South Carolina, and
 Street SW., 12th Floor, Atlanta, GA      Tennessee.
 30303, (404) 562-9127.
John Mooney, Chief, Air Programs         Illinois, Indiana, Michigan,
 Branch, EPA Region V, 77 West Jackson    Minnesota, Ohio, and
 Street, Chicago, IL 60604, (312) 886-    Wisconsin.
 6043.
Alan Shar, Acting Chief, Air Planning    Arkansas, Louisiana, New
 Section, EPA Region VI, 1445 Ross        Mexico, Oklahoma, and Texas.
 Avenue, Dallas, TX 75202, (214) 665-
 6691.
Mike Jay, Chief, Air Programs Branch,    Iowa, Kansas, Missouri, and
 EPA Region VII, 11201 Renner Blvd.,      Nebraska.
 Lenexa, KS 66129, (913) 551-7460.
Monica Morales, Air Program Director,    Colorado, Montana, North
 EPA Region VIII, 1595 Wynkoop Street,    Dakota, South Dakota, Utah,
 Denver, CO 80202-1129, (303) 312-6936.   and Wyoming.
Doris Lo, Air Planning Office, EPA       American Samoa, Arizona,
 Region IX, 75 Hawthorne Street, San      California, Guam, Hawaii,
 Francisco, CA 94105, (415) 972-3959.     Nevada, Northern Mariana
                                          Islands, Navajo Nation, and
                                          the Hopi Tribe.
Debra Suzuki, Manager, State and Tribal  Alaska, Idaho, Oregon, and
 Air Programs, EPA Region X, Office of    Washington.
 Air, Waste, and Toxics, Mail Code OAQ-
 107, 1200 Sixth Avenue, Seattle, WA
 98101, (206) 553-0985.
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    The information can also be reviewed online at https://www.epa.gov/sulfur-dioxide-designations and also in the public docket for these 
SO2 designations at https://www.regulations.gov under Docket 
ID No. EPA-HQ-OAR-2017-0003.

FOR FURTHER INFORMATION CONTACT: For general questions concerning this 
action, please contact Liz Etchells, U.S. EPA, Office of Air Quality 
Planning and Standards, Air Quality Policy Division, C539-01, Research 
Triangle Park, NC 27709, telephone (919) 541-0253, email at 
[email protected]. The following EPA contacts can answer 
questions regarding areas in a particular EPA Regional office:

U.S. EPA Regional Office Contacts

    Region I--Leiran Biton, telephone (617) 918-1267, email at 
[email protected].
    Region II--Ken Fradkin, telephone (212) 637-3702, email at 
[email protected].
    Region III--Ruth Knapp, telephone (215) 814-2191, email at 
[email protected].
    Region IV--Twunjala Bradley, telephone (404) 562-9352, email at 
[email protected].
    Region V--John Summerhays, telephone (312) 886-6067, email at 
[email protected].

[[Page 41904]]

    Region VI--Dayana Medina, telephone (214) 665-7241, email at 
[email protected].
    Region VII--David Peter, telephone (913) 551-7397, email at 
[email protected].
    Region VIII--Adam Clark, telephone (303) 312-7104, email at 
[email protected].
    Region IX--Anita Lee, telephone (415) 972-3958, email at 
[email protected].
    Region X--John Chi, telephone (206) 553-1185, email at 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

    The following is an outline of the Preamble.

I. What is the purpose of this action?
II. Instructions for Submitting Public Comments and Internet Web 
Site for Rulemaking Information
III. What is the 2010 SO[bdi2] NAAQS and what are the health 
concerns that it addresses?
IV. What are the CAA requirements for air quality designations and 
what action has the EPA taken to meet these requirements?
V. What guidance has the EPA previously issue and how does the EPA 
now intend to apply the statutory requirements to determine area 
designations and boundaries?
VI. What air quality information has the EPA used for these intended 
designations?
VII. How do the Round 3 designations affect Indian country?
VIII. Where can I find information forming the basis for the EPA's 
intended rule and exchanges between the EPA, states, and tribes 
related to this intended rule?

I. What is the purpose of this action?

    The purpose of this action of availability is to solicit input from 
interested parties other than states on the EPA's recent responses to 
the state designation recommendations for the 2010 SO2 
NAAQS. These responses, and their supporting technical analyses, can be 
found at https://www.epa.gov/sulfur-dioxide-designations and also in 
the public docket for these SO2 designations at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2017-0003.
    On June 2, 2010, the EPA Administrator signed a notice of final 
rulemaking that revised the primary SO2 NAAQS (75 FR 35520; 
June 22, 2010) after review of the existing primary SO2 
standards promulgated on April 30, 1971 (36 FR 8187). The EPA 
established the revised primary SO2 NAAQS at 75 parts per 
billion (ppb) which is attained when the 3-year average of the annual 
99th percentile of 1-hour daily maximum concentrations does not exceed 
75 ppb.
    The process for designating areas following promulgation of a new 
or revised NAAQS is contained in the Clean Air Act (CAA or Act) section 
107(d) (42 U.S.C. 7407). After promulgation of a new or revised NAAQS, 
each governor or tribal leader has an opportunity to recommend air 
quality designations, including the appropriate boundaries for 
nonattainment areas, to the EPA. The EPA considers these 
recommendations as part of its duty to promulgate the formal area 
designations and boundaries for the new or revised NAAQS. By no later 
than 120 days prior to promulgating designations, the EPA is required 
to notify states, territories, and tribes, as appropriate, of any 
intended modifications to an area designation or boundary 
recommendation that the EPA deems necessary.
    After invoking a 1-year extension of the deadlines to designate 
areas, as provided for in section 107 of the Act, the EPA completed an 
initial round of SO2 designations for certain areas of the 
country on July 25, 2013 (referred to as ``Round 1'').\1\ Following the 
initial designations, three lawsuits were filed against the EPA in 
different U.S. District Courts, alleging the agency had failed to 
perform a nondiscretionary duty under the CAA by not designating all 
portions of the country by the June 2, 2013, deadline. In one of those 
cases, the U.S. District Court for the Northern District of California 
on March 2, 2015, entered an enforceable order for the EPA to complete 
the area designations by three specific deadlines according to the 
court-ordered schedule.
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    \1\ A total of 29 areas throughout the U.S. were designated in 
this action published on August 5, 2013 (78 FR 47191). The EPA 
designated all 29 areas nonattainment based on violating monitored 
SO2 concentrations from Federal Reference Method and 
Federal Equivalent Method monitors that are sited and operated in 
accordance with 40 CFR parts 50 and 58, and did not at that time 
designate any other areas.
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    To meet the first court-ordered deadline, additional areas were 
designated on June 30, 2016, and November 29, 2016 (collectively 
referred to as ``Round 2'').\2\ Pursuant to the court-ordered 
schedule,\3\ the EPA must complete SO2 designations for the 
remaining areas of the country by two specific deadlines: December 31, 
2017, and December 31, 2020. This current third round of designations 
addresses all remaining undesignated areas except those where a state 
\4\ has installed and begun timely operating a new SO2 
monitoring network meeting EPA specifications referenced in EPA's 
SO2 Data Requirements Rule.\5\
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    \2\ A total of 65 areas throughout the U.S. were designated in 
these actions published on July 12, 2016 (81 FR 45039), and December 
13, 2016 (81 FR 89870). Of these 65 areas, seven were designated 
nonattainment.
    \3\ Sierra Club v. McCarthy, No. 3-13-cv-3953 (SI) (N.D. Cal. 
Mar. 2, 2015).
    \4\ In Mineral County, West Virginia, a new SO2 
monitor was installed and is operated by the state of Maryland.
    \5\ 40 CFR part 51, subpart BB (80 FR 51052; August 21, 2015).
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    On or about August 22, 2017, consistent with section 
107(d)(1)(b)(ii) of the CAA, the EPA notified affected states, 
territories, and tribes of our assessment of their recommended 
designations for Round 3. While we are in agreement with the 
recommendations for many areas, some warrant further discussion. We 
stand ready to assist and hope to resolve any differences regarding the 
proper designation for these areas within the 120-day process provided 
by the CAA.
    For any areas that we designate nonattainment in our final action, 
the CAA directs states to develop and submit to the EPA State 
Implementation Plans (SIPs) within 18 months of the effective date of 
the final rule, that meet the requirements of sections 172(c) and 191-
192 of the CAA and provide for attainment of the NAAQS as expeditiously 
as practicable, but not later than 5 years from the effective date of 
the final rule.

II. Instructions for Submitting Public Comments and Internet Web Site 
for Rulemaking Information

A. Invitation To Comment

    The purpose of this action is to solicit input from interested 
parties, other than the states, territories, and tribes to which we 
have sent notification letters, on the EPA's recent responses to the 
designation recommendations for the 2010 SO2 NAAQS. These 
responses, and their supporting technical analyses, can be found at 
https://www.epa.gov/sulfur-dioxide-designations and also in the public 
docket for these SO2 designations at Docket ID No. EPA-HQ-
OAR-2017-0003. Air dispersion modeling input and output files are too 
large to post in the docket or on the Web site and must be requested 
from the EPA Docket Office or the Regional office contacts listed in 
the beginning of this document. The EPA Docket Office can be contacted 
at (202) 566-1744, and is located at EPA Docket Center Reading Room, 
WJC West Building, Room 3334, 1301 Constitution Avenue NW., Washington, 
DC 20004. The hours of operation at the EPA Docket Center are 8:30 
a.m.-4:30 p.m., Monday-Friday.
    CAA section 107(d) provides a process for air quality designations 
that

[[Page 41905]]

involves recommendations by states, territories, and tribes to the EPA 
and responses from the EPA to those parties, prior to the EPA 
promulgating final area designations and boundaries. The EPA is not 
required under the CAA section 107(d) to seek public comment during the 
designation process, but we are electing to do so for these areas with 
respect to the 2010 SO2 NAAQS in order to gather additional 
information for the EPA to consider before making final designations 
for the specific areas addressed in the EPA's recent letters to states, 
territories, and tribes. The EPA invites public input on our responses 
to states regarding these areas during the 30-day comment period 
provided in this action. In order to receive full consideration, input 
from the public must be submitted to the docket by October 5, 2017. At 
this time, the EPA is not asking for public comments on areas beyond 
those areas that are the subject of this proposed action. This action 
and opportunity for public comment does not affect any rights or 
obligations of any state, territory, or tribe, or of the EPA, which 
might otherwise exist pursuant to the CAA section 107(d).
    Please refer to the ADDRESSES section in this document for specific 
instructions on submitting comments and locating relevant public 
documents.
    For some cases, the EPA has indicated to a state or territory that 
further discussion is needed--e.g., where the state recommended a 
designation of unclassifiable/attainment (or unclassifiable) and 
available air quality monitoring or modeling data show that the area 
may be violating the 2010 primary SO2 NAAQS or contain 
sources that may be contributing to air quality in a nearby area that 
may be violating the 2010 primary SO2 NAAQS. In establishing 
nonattainment area boundaries for a particular area, the EPA is 
required to include within the boundaries both the area that does not 
meet the standard and any nearby area contributing to the area that 
does not meet the standard. We are particularly interested in receiving 
comments, supported by relevant information, if you believe that a 
specific geographic area for which further discussion is needed 
concerning a state's recommended designation of unclassifiable/
attainment or unclassifiable (and for which available air quality data 
would require a modification of the recommended designation) should not 
be categorized by the CAA section 107(d) criteria as nonattainment, or 
if you believe that a specific nearby area for which the EPA does agree 
with a state's recommended designation of unclassifiable/attainment or 
unclassifiable should in fact be categorized as contributing to 
nonattainment using the CAA section 107(d) criteria. Please be as 
specific as possible in supporting your views.
     Describe any assumptions and provide any technical 
information and/or data that you used.
     Provide specific examples to illustrate your concerns, and 
suggest alternatives.
     Explain your views as clearly as possible.
     Provide your input by the comment period deadline 
identified.
    The EPA intends to complete designations for the areas subject to 
this round no later than December 31, 2017. The EPA is not yet prepared 
to respond to state and tribal area designation recommendations, or 
seek public input thereon, for areas that will be designated in Round 4 
for the 2010 SO2 NAAQS. The EPA is required to address those 
areas by December 31, 2020. Additional information on the EPA's 
intended approach for addressing designations for all areas can be 
found on the EPA's SO2 implementation Web site at https://www.epa.gov/so2-pollution/applying-or-implementing-sulfur-dioxide-standards.

B. What should I consider as I prepare my comments for the EPA?

    1. Submitting CBI. Do not submit CBI information to the EPA through 
https://www.regulations.gov or email. Clearly mark the part or all of 
the information that you claim to be CBI. For CBI 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 Code of Federal Regulations (CFR) part 2. Send or deliver 
information identified as CBI only to the following address: Tiffany 
Purifoy, OAQPS CBI Officer, U.S. EPA, Office of Air Quality Planning 
and Standards, Mail Code C404-02, Research Triangle Park, NC 27711, 
telephone (919) 541-0878, email at [email protected], Attention 
Docket ID No. EPA-HQ-OAR-2017-0003.
    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.
     Explain why you agree or disagree; suggest alternatives 
and substitute language for your requested changes.

C. Where can I find additional information for this rulemaking?

    The EPA has also established a Web site for this rulemaking at 
https://www.epa.gov/sulfur-dioxide-designations. The Web site includes 
the state, territorial and tribal recommendations, the EPA's intended 
area designations, information supporting the EPA's preliminary 
designation decisions, as well as the rulemaking actions and other 
related information that the public may find useful.

III. What is the 2010 SO2 NAAQS and what are the health 
concerns that it addresses?

    The Administrator signed a final rule revising the primary 
SO2 NAAQS on June 2, 2010. The rule was published in the 
Federal Register on June 22, 2010 (75 FR 35520) and became effective on 
August 23, 2010. Specifically, the EPA established a new 1-hour 
SO2 standard at a level of 75 ppb, which is met at an 
ambient air quality 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, as determined in accordance with Appendix T of 
40 CFR part 50. 40 CFR 50.17(a) and (b). Current scientific evidence 
links short-term exposures to SO2, ranging from 5 minutes to 
24 hours, with an array of adverse respiratory effects including 
bronchoconstriction and increased asthma symptoms. Studies also show a 
connection between short-term exposure and increased visits to 
emergency departments and hospital admissions for respiratory 
illnesses, particularly in at-risk populations including children, the 
elderly, and asthmatics.\6\
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    \6\ See 75 FR 35520 at 35525, June 22, 2010.
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IV. What are the CAA requirements for air quality designations and what 
action has the EPA taken to meet these requirements?

    After the EPA promulgates a new or revised NAAQS, the EPA is 
required to designate all areas of the country as either 
``nonattainment,'' ``attainment,'' or ``unclassifiable,'' for that 
NAAQS pursuant to section 107(d)(1) of the CAA. As part of these Round 
3

[[Page 41906]]

designations, EPA is implementing its interpretation of statutory terms 
under CAA section 107(d) nationwide and is basing these designations on 
EPA's nationwide analytical approach and technical analysis, including 
evaluation of monitoring data and air quality modeling, applied to the 
available evidence for each area.
    Regarding statutory definitions and the EPA's interpretations of 
such, the section 107(d)(1)(A)(i) of the CAA defines a nonattainment 
area as an area that does not meet the NAAQS or that contributes to a 
nearby area that does not meet the NAAQS. An attainment area is defined 
by the CAA as any area that meets the NAAQS and does not contribute to 
a nearby area that does not meet the NAAQS. Unclassifiable areas are 
defined by the CAA as those that cannot be classified on the basis of 
available information as meeting or not meeting the NAAQS.
    In this action, the EPA defines a nonattainment area as an area 
that the EPA has determined violates the 2010 SO2 NAAQS or 
contributes to a violation in a nearby area, based on the most recent 3 
years of air quality monitoring data, appropriate dispersion modeling 
analysis, and any other relevant information. In this action, an 
unclassifiable/attainment area is defined by EPA as an area that 
either: (1) Based on available information including (but not limited 
to) appropriate modeling analyses and/or monitoring data, EPA has 
determined (i) meets the 2010 SO2 NAAQS, and (ii) does not 
contribute to ambient air quality in a nearby area that does not meet 
the NAAQS; or (2) was not required to be characterized under 40 CFR 
51.1203(c) or (d) and EPA does not have available information including 
(but not limited to) appropriate modeling analyses and/or monitoring 
data that suggests that the area may (i) not be meeting the NAAQS, or 
(ii) contribute to ambient air quality in a nearby area that does not 
meet the NAAQS. In this action, an unclassifiable area is defined by 
the EPA as an area that either: (1) Was required to be characterized by 
the state under 40 CFR 51.1203(c) or (d), has not been previously 
designated, and on the basis of available information cannot be 
classified as either: (i) Meeting or not meeting the 2010 
SO2 NAAQS, or (ii) contributing or not contributing to 
ambient air quality in a nearby area that does not meet the NAAQS; or 
(2) was not required to be characterized under 40 CFR 51.1203(c) or (d) 
and the EPA does have available information including (but not limited 
to) appropriate modeling analyses and/or monitoring data that suggests 
that the area may (i) not be meeting the NAAQS, or (ii) contribute to 
ambient air quality in a nearby area that does not meet the NAAQS.
    These definitions refer to 40 CFR 51.1203(c) and (d), which are 
part of EPA's Data Requirements Rule. The citation to these CFR 
sections is in effect a reference to any area that contains a source, 
generally one emitting more than 2,000 tons per year of SO2 
or was otherwise listed under the DRR, with respect to which the state 
has indicated that it will comply with the Data Requirements Rule 
either by establishing a new monitoring network or by submitting an air 
quality modeling analysis.
    This nationwide analytical approach also includes but is not 
limited to: (1) EPA's interpretations of other terms in the context of 
Round 3 of the 2010 SO2 NAAQS; (2) the appropriate basis for 
characterizing the air quality of an area; (3) the five-factor analysis 
to determine the boundaries for each air quality area under the NAAQS; 
and (4) the methodology for appropriately characterizing SO2 
air quality through monitoring or modeling.
    The EPA notes that CAA section 107(d) provides the agency with 
discretion to determine how best to interpret the terms in the 
definition of a nonattainment area (e.g., ``contributes to'' and 
``nearby'') for a new or revised NAAQS, given considerations such as 
the nature of a specific pollutant, the types of sources that may 
contribute to violations, the form of the standards for the pollutant, 
and other relevant information. In particular, the EPA's position is 
that the statute does not require the agency to establish bright line 
tests or thresholds for what constitutes ``contribution'' or ``nearby'' 
for purposes of designations.\7\
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    \7\ This view was confirmed in Catawba County v. EPA, 571 F.3d 
20 (D.C. Cir. 2009).
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    Similarly, the EPA's position is that the statute permits the EPA 
to evaluate the appropriate application of the term ``area'' to include 
geographic areas based upon full or partial county boundaries, as may 
be appropriate for a particular NAAQS. For example, CAA section 
107(d)(1)(B)(ii) explicitly provides that the EPA can make 
modifications to designation recommendations for an area ``or portions 
thereof,'' and under CAA section 107(d)(1)(B)(iv) a designation remains 
in effect for an area ``or portion thereof'' until the EPA redesignates 
it.
    By no later than 1 year after the promulgation of a new or revised 
NAAQS, CAA section 107(d)(1)(A) provides that each state governor is 
required to recommend air quality designations, including the 
appropriate boundaries for areas, to the EPA.\8\ The EPA reviews those 
recommendations and is authorized to make any modifications the 
Administrator deems necessary. The statute does not define the term 
``necessary,'' but the EPA interprets this to authorize the 
Administrator to modify designations that did not meet the statutory 
requirements or were otherwise inconsistent with the facts or analysis 
deemed appropriate by the Administrator. If the EPA is considering 
modifications to a recommendation, we are required by CAA section 
107(d)(1)(B)(ii) to notify the state of any such intended modifications 
not less than 120 days prior to our promulgation of the final 
designation. These notifications are commonly known as the ``120-day 
letters.'' During this period, if the state or territory does not agree 
with the EPA's modification, it has an opportunity to respond to the 
EPA and to demonstrate why it believes the modification proposed by the 
EPA is inappropriate. If a state or territory fails to provide any 
recommendation for an area, in whole or in part, the EPA still must 
promulgate a designation that the Administrator deems appropriate, 
pursuant to CAA section 107(d)(1)(B)(ii). While CAA section 107(d) 
specifically addresses the designations process between the EPA and 
states and territories, the EPA intends to follow the same process to 
the extent practicable for tribes that submitted designation 
recommendations.
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    \8\ Tribes are invited to submit recommendations following 
promulgation of a new or revised NAAQS, but are not required to do 
so.
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V. What guidance has the EPA previously issued and how does the EPA now 
intend to apply the statutory requirements to determine area 
designations and boundaries?

    In the notice of proposed rulemaking for the revised SO2 
NAAQS (74 FR 64810; December 8, 2009), the EPA issued proposed guidance 
on our approach to implementing the standard, including our approach to 
initial area designations. The EPA solicited comment on that guidance 
and, in the notice of final rulemaking (75 FR 35520; June 22, 2010), 
provided further guidance concerning implementation of the standard and 
how to identify nonattainment areas and boundaries for the 
SO2 NAAQS. Subsequently, on March 24, 2011, the EPA provided 
additional designations guidance to assist states with making their

[[Page 41907]]

recommendations for area designations and boundaries.\9\ That guidance 
recommended, among other things, that monitoring data from the most 
recent 3 consecutive years be used to identify a violation of the 
SO2 NAAQS. This is appropriate because the form of the 
SO2 NAAQS is calculated as a 3-year average of the 99th 
percentile of the yearly distribution of 1-hour daily maximum 
SO2 concentrations (specifically the most recent 3 
consecutive years). The EPA based the first round of final 
SO2 designations in 2013 solely on violating monitored 
SO2 concentrations for the years 2010-2012 from Federal 
Reference Method and Federal Equivalent Method monitors that are sited 
and operated in accordance with 40 CFR parts 50 and 58, and did not at 
that time designate any other areas.
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    \9\ See, ``Area Designations for the 2010 Revised Primary Sulfur 
Dioxide National Ambient Air Quality Standards,'' memorandum to 
Regional Air Division Directors, Regions I-X, from Stephen D. Page, 
dated March 24, 2011.
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    In the March 24, 2011, guidance, the EPA stated that the perimeter 
of a county containing a violating monitor would be the initial 
presumptive boundary for nonattainment areas, but also stated that the 
state, tribe and/or the EPA could conduct additional area-specific 
analyses that could justify establishing either a larger or smaller 
area. The EPA indicated that the following factors should be considered 
in an analysis of whether to exclude portions of a county and whether 
to include additional nearby areas outside the county as part of the 
designated nonattainment area: (1) Air quality data; (2) emissions-
related data; (3) meteorology; (4) geography/topography; and (5) 
jurisdictional boundaries, as well as other available data. States and 
tribes may identify and evaluate other relevant factors or 
circumstances specific to a particular area.
    Following entry of the March 2, 2015, court order setting forth the 
schedule for the EPA to complete SO2 designations, the EPA 
issued updated designations guidance.\10\ This guidance superseded the 
March 24, 2011, designation guidance for the 2010 SO2 NAAQS, 
and identified factors that the EPA intended to evaluate in determining 
whether areas are in violation of the 2010 SO2 NAAQS or 
contribute to air quality in nearby areas that are in violation of the 
2010 SO2 NAAQS. The guidance also contained the factors the 
EPA intended to evaluate in determining the boundaries for all 
remaining areas in the country, consistent with the court's order and 
schedule. These factors include: (1) Air quality characterization via 
ambient monitoring or dispersion modeling results; (2) emissions-
related data; (3) meteorology; (4) geography and topography; and (5) 
jurisdictional boundaries.\11\
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    \10\ See, ``Updated Guidance for Area Designations for the 2010 
Primary Sulfur Dioxide National Ambient Air Quality Standard,'' 
memorandum to Regional Air Division Directors, Regions I-X, from 
Stephen D. Page, dated March 20, 2015.
    \11\ The EPA supplemented this guidance with documents first 
made available to states and other interested parties in 2013 and 
updated in 2016. See SO2 NAAQS Designations Source-
Oriented Monitoring Technical Assistance Document (February 2016), 
available at https://www.epa.gov/sites/production/files/2016-06/documents/so2monitoringtad.pdf, and SO2 NAAQS 
Designations Modeling Technical Assistance Document (August 2016), 
available at https://www.epa.gov/sites/production/files/2016-06/documents/so2modelingtad.pdf.
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    On March 8, 2017, the EPA issued a memo to clarify what version of 
the AERMOD modeling system is the most appropriate for consideration by 
the agency in the SO2 designations process.\12\
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    \12\ See ``Clarification on the AERMOD Modeling System Version 
for Use in SO2 Implementation Efforts and Other 
Regulatory Actions,'' memorandum to EPA Regional Air Division 
Directors from Richard A. Wayland, dated March 8, 2017. This memo is 
available at https://www3.epa.gov/ttn/scram/guidance/clarification/SO2_DRR_Designation_Modeling_Clarification_Memo-03082017.pdf.
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VI. What air quality information has the EPA used for these intended 
designations?

    For designations for the SO2 NAAQS, air agencies have 
the flexibility to characterize air quality using either appropriately 
sited ambient air quality monitors or modeling of actual or allowable 
source emissions.
    These intended designations are based on the EPA's application of 
the nationwide analytical approach to, and preliminary technical 
assessment of, the weight of evidence for each area, including but not 
limited to available air quality monitoring data and air quality 
modeling results. With respect to air quality monitoring data, the EPA 
has considered data from at least the most recent 3 calendar years, 
i.e., 2014-2016, as available. In most of the modeling runs available 
for EPA's review, the impacts of the actual emissions for one or more 
of the 3-year periods 2012-2014, 2013-2015, or 2014-2016 were 
considered, and in some cases the modeling was of recently effective or 
not-yet-effective limits on allowable emissions in lieu of or as a 
supplement to modeling of actual emissions. The 1-hour primary 
SO2 standard is violated at an ambient air quality 
monitoring site (or in the case of dispersion modeling, at an ambient 
air quality receptor location) when the 3-year average of the annual 
99th percentile of the daily maximum 1-hour average concentrations 
exceeds 75 ppb, as determined in accordance with Appendix T of 40 CFR 
part 50.

VII. How do the Round 3 designations affect Indian country?

    For areas of Indian country, there are no violating monitors. The 
Navajo Nation submitted modeling analyses for the areas around two 
SO2 emission sources located in the Navajo Nation, the 
Navajo Generating Station and the Four Corners Power Plant, neither of 
which indicated a violation of the NAAQS. The Navajo Nation and the 
lands of the Hopi Tribe are being designated as separate areas. No 
areas of Indian country are being designated as nonattainment as part 
of this round. Any other parts of Indian country being designated as 
unclassifiable/attainment or unclassifiable are being designated along 
with the surrounding state area.

VIII. Where can I find information forming the basis for this intended 
rule and exchanges between the EPA, states, and tribes related to this 
intended rule?

    Information providing the basis for this intended action are 
provided in a technical support document (TSD) \13\ included in the 
docket. The TSD, modeling files, technical assistance documents, 
applicable EPA guidance memoranda, and copies of correspondence 
regarding this process between the EPA and the states, territories, 
tribes, and other parties, are available for review at the public 
docket for these SO2 designations at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2017-0003, at the 
EPA Docket Center listed in the ADDRESSES section of this document and 
on the agency's SO2 Designations Web site at https://www.epa.gov/sulfur-dioxide-designations. Area-specific questions can be 
addressed to the EPA Regional offices (see contact information provided 
at the beginning of this document).
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    \13\ The single TSD for this action consists of a few sections 
with information that applies to all affected areas or to certain 
groups of areas with some common features, and many sections that 
are specific to individual states, territories, or tribal areas. For 
convenience, the term ``TSD'' is also used generically to refer to 
these state/territory/tribe-specific sections. For informational 
purposes, these individual state/territory/tribe-specific sections/
TSDs are available for separate downloading from the indicated EPA 
Web site.


[[Page 41908]]


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    Dated: August 22, 2017.
Mary E. Henigin,
Acting Director, Office of Air Quality Planning & Standards.
[FR Doc. 2017-18423 Filed 9-1-17; 8:45 am]
BILLING CODE 6560-50-P