Document ID: EPA-R08-OAR-2016-0521-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Wyoming; Interstate Transport
Posted Date: 2016-11-18T05:00Z

[Federal Register Volume 81, Number 223 (Friday, November 18, 2016)]
[Proposed Rules]
[Pages 81712-81718]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-27672]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2016-0521; FRL-9955-31-Region 8]

Approval and Disapproval and Promulgation of Air Quality 
Implementation Plans; Interstate Transport for Wyoming

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing action 
on the portions of six submissions from the State of Wyoming that are 
intended to demonstrate that the State Implementation Plan (SIP) meets 
certain interstate transport requirements of the Clean Air Act (Act or 
CAA). These submissions address the 2006 and 2012 fine particulate 
matter (PM2.5) National Ambient Air Quality Standards 
(NAAQS), 2008 ozone NAAQS, 2008 lead (Pb) NAAQS, 2010 sulfur dioxide 
(SO2) NAAQS and 2010 nitrogen dioxide (NO2) 
NAAQS. The interstate transport requirements under the CAA consist of 
four elements: Significant contribution to nonattainment (prong 1) and 
interference with maintenance (prong 2) of the NAAQS in other states; 
and interference with measures required to be included in the plan for 
other states to prevent significant deterioration of air quality (prong 
3) or to protect visibility (prong 4). Specifically, the EPA is 
proposing to approve interstate transport prongs 1 and 2 for the 2008 
Pb and 2010 NO2 NAAQS, and proposing to approve prong 1 and 
disapprove prong 2 for the 2008 ozone NAAQS. The EPA is also proposing 
to approve interstate transport prong 4 for the 2008 Pb and 2010 
SO2 NAAQS, and proposing to disapprove prong 4 for the 2006 
PM2.5, 2008 ozone, 2010 NO2 and 2012 
PM2.5 NAAQS.

DATES: Comments must be received on or before December 19, 2016.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2016-0521 at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from www.regulations.gov. The EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Adam Clark, Air Program, U.S. 
Environmental Protection Agency, Region 8, Mail Code 8P-AR, 1595 
Wynkoop Street, 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 EPA through http://www.regulations.gov or email. Clearly 
mark the part or all of the information that you claim to be CBI. For 
CBI information on 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 volume, 
date, and page number);
     Follow directions and organize your comments;
     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;
     Explain your views as clearly as possible, avoiding the 
use of profanity or personal threats; and
     Make sure to submit your comments by the comment period 
deadline identified.

II. Background

    On September 21, 2006, the EPA revised the primary 24-hour NAAQS 
for PM2.5 to 35 micrograms per cubic meter

[[Page 81713]]

([micro]g/m\3\). 71 FR 61144 (Oct. 17, 2006). On March 12, 2008, the 
EPA revised the levels of the primary and secondary 8-hour ozone 
standards to 0.075 parts per million (ppm). 73 FR 16436 (Mar. 27, 
2008). On October 15, 2008, the EPA revised the level of the primary 
and secondary Pb NAAQS to 0.15 [mu]g/m\3\. 73 FR 66964 (Nov. 12, 2008). 
On January 22, 2010, the EPA promulgated a new 1-hour primary NAAQS for 
NO2 at a level of 100 parts per billion (ppb) while 
retaining the annual standard of 53 ppb. 75 FR 6474 (Feb. 9, 2010). The 
secondary NO2 NAAQS remains unchanged at 53 ppb. On June 2, 
2010, the EPA promulgated a revised primary 1-hour SO2 
standard at 75 ppb. 75 FR 35520 (June 22, 2010). Finally, on December 
14, 2012, the EPA promulgated a revised annual PM2.5 
standard by lowering the level to 12.0 [mu]g/m\3\ and retaining the 24-
hour PM2.5 standard at a level of 35 [mu]g/m\3\. 78 FR 3086 
(Jan. 15, 2013).
    Pursuant to section 110(a)(1) of the CAA, states are required to 
submit SIPs meeting the applicable requirements of section 110(a)(2) 
within three years after promulgation of a new or revised NAAQS or 
within such shorter period as the EPA may prescribe. Section 110(a)(2) 
requires states to address structural SIP elements such as requirements 
for monitoring, basic program requirements, and legal authority that 
are designed to provide for implementation, maintenance and enforcement 
of the NAAQS. The SIP submission required by these provisions is 
referred to as the ``infrastructure'' SIP. Section 110(a) imposes the 
obligation upon states to make a SIP submission to the EPA for a new or 
revised NAAQS, but the contents of individual state submissions may 
vary depending upon the facts and circumstances.
    CAA Section 110(a)(2)(D)(i)(I) requires SIPs to include provisions 
prohibiting any source or other type of emissions activity in one state 
from emitting any air pollutant in amounts that will contribute 
significantly to nonattainment, or interfere with maintenance, of the 
NAAQS in another state. The two provisions of this section are referred 
to as prong 1 (significant contribution to nonattainment) and prong 2 
(interfere with maintenance). Section 110(a)(2)(D)(i)(II) requires SIPs 
to contain adequate provisions to prohibit emissions that will 
interfere with measures required to be included in the applicable 
implementation plan for any other state under part C to prevent 
significant deterioration of air quality (prong 3) or to protect 
visibility (prong 4).
    The Wyoming Department of Environmental Quality (Department or 
WDEQ) submitted the following: A certification of Wyoming's 
infrastructure SIP for the 2006 PM2.5 NAAQS on August 19, 
2011; a certification of Wyoming's infrastructure SIP for the 2008 Pb 
SIP on October 12, 2011; a certification of Wyoming's infrastructure 
SIP for the 2008 ozone NAAQS on February 6, 2014; a certification of 
Wyoming's infrastructure SIP for the 2010 NO2 NAAQS on 
January 24, 2014; a certification of Wyoming's infrastructure SIP for 
the 2010 SO2 NAAQS on March 6, 2015; and a certification of 
Wyoming's infrastructure SIP for the 2012 PM2.5 on June 24, 
2016.
    Each of these infrastructure certifications addressed all of the 
infrastructure elements including section 110(a)(2)(D)(i)(I), referred 
to as infrastructure element (D).\1\ In this action, we are only 
addressing element (D) prongs 1, 2 and 4 for the 2008 Pb certification, 
2008 ozone certification and 2010 NO2 certification, and 
prong 4 from the 2010 SO2 and 2006 and 2012 PM2.5 
certifications. All other infrastructure elements from these 
certifications, including element (D) prong 3 (prevent significant 
deterioration of air quality), have been or will be addressed in 
separate actions.
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    \1\ For discussion of other infrastructure elements, see EPA's 
``Guidance on Infrastructure State Implementation Plan (SIP) 
Elements under Clean Air Act Sections 110(a)(1) and (2),'' September 
13, 2013.
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III. Evaluation of Significant Contribution to Nonattainment and 
Interference With Maintenance of the NAAQS

2008 Ozone NAAQS

    In its February 6, 2014 infrastructure submittal for the 2008 ozone 
NAAQS, WDEQ addressed 110(a)(2)(D)(i)(I) prongs 1 and 2 by presenting 
ambient monitoring and wind rose data, among other information,\2\ to 
determine that emissions from Wyoming do not significantly contribute 
to nonattainment or interfere with maintenance of the 2008 ozone NAAQS 
in any other state. WDEQ focused its analysis on nearby designated 
nonattainment areas, and in particular, on a nonattainment area in and 
around Denver, Colorado.\3\ Specifically, WDEQ pointed to the attaining 
ozone data at a Cheyenne, Wyoming monitor, which is the monitor in 
Wyoming that is geographically located closest to the Denver, Colorado 
2008 ozone nonattainment area. WDEQ also provided wind rose data in 
Cheyenne, Wyoming, which showed that prevailing winds in Cheyenne came 
from the west and northwest, which WDEQ asserts indicates the transport 
of air pollutants is away from the Denver nonattainment area, which is 
located 30 miles south of the southeastern Wyoming border. WDEQ 
concludes that the combination of low ozone monitor values in Cheyenne, 
Wyoming, and prevailing winds provided evidence that emissions from 
Wyoming do not significantly influence air quality in the Denver ozone 
nonattainment area. WDEQ also noted that downwind states Kansas, 
Nebraska, North Dakota and South Dakota did not contain nonattainment 
areas to which Wyoming could significantly contribute. Accordingly, 
WDEQ concludes that emissions from Wyoming do not contribute to 
nonattainment or interfere with maintenance for the 2008 ozone NAAQS in 
any other state.
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    \2\ The State also provided census data and geographic 
information to support their assertion regarding prongs 1 and 2 in 
the February 6, 2014 submittal.
    \3\ The Denver area, including 7 full counties and 2 partial 
counties, was designated as a marginal nonattainment area in a final 
action dated May 21, 2012. See 77 FR 30110.
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    WDEQ's approach to evaluating its compliance with the CAA section 
110(a)(2)(D)(i)(I) as to the 2008 ozone NAAQS is incomplete for two 
reasons. First, transported emissions may cause an area to measure 
exceedances of the standard even if that area is not formally 
designated nonattainment by the EPA. While WDEQ considered its 
potential impact to the Denver nonattainment area based on general wind 
patterns, the State did not provide analysis showing that it did not 
contribute to ozone levels in the Denver nonattainment area on the 
particular days with measured exceedances. Moreover, while the State 
considered whether there were designated nonattainment areas in four of 
several nearby states, WDEQ did not evaluate whether it contributed to 
ozone levels elsewhere in Colorado or in other nearby states (e.g., in 
Utah) on the days with measured exceedances, whether or not those 
exceedances occurred in designated nonattainment areas. The EPA has 
routinely interpreted the obligation to prohibit emissions that 
``significantly contribute to nonattainment'' of the NAAQS in downwind 
states to be independent of formal designations because exceedances can 
happen in any area.\4\

[[Page 81714]]

Thus, WDEQ did not fully evaluate whether emissions from the State 
significantly contribute to nonattainment in other states as required 
by prong 1 of element (D).
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    \4\ See, e.g., Clean Air Interstate Rule, 70 FR 25162, 25265 
(May 12, 2005) (``As to impacts, CAA section 110(a)(2)(D) refers 
only to prevention of `nonattainment' in other States, not to 
prevention of nonattainment in designated nonattainment areas or any 
similar formulation requiring that designations for downwind 
nonattainment areas must first have occurred.''); Cross-State Air 
Pollution Rule, 76 FR 48208, 48211 (Aug. 8, 2011) (evaluating 
nonattainment and maintenance concerns based on modeled 
projections); Brief for Respondents U.S. Environmental Protection 
Agency at 23-24, EME Homer City Generation, L.P. v. EPA, Case No. 
11-1302 (D.C. Cir. Jan. 16, 2015), ECF No. 1532516 (defending the 
EPA's identification of air quality problems in CSAPR independent of 
area designations). Cf. Final Response to Petition from New Jersey 
Regarding SO2 Emissions From the Portland Generating 
Station, 76 FR 69052 (Nov. 7, 2011) (finding facility in violation 
of the prohibitions of CAA section 110(a)(2)(D)(i)(I) with respect 
to the 2010 SO2 NAAQS prior to issuance of designations 
for that standard).
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    Second, WDEQ's submission does not provide any technical analysis 
demonstrating that the SIP contains adequate provisions prohibiting 
emissions that will interfere with maintenance of the 2008 ozone NAAQS 
in any other state (prong 2). In remanding the Clean Air Interstate 
Rule (CAIR) to the EPA in North Carolina v. EPA, the D.C. Circuit 
explained that the regulating authority must give the ``interfere with 
maintenance'' clause of section 110(a)(2)(D)(i)(I) ``independent 
significance'' by evaluating the impact of upwind state emissions on 
downwind areas that, while currently in attainment, are at risk of 
future nonattainment, considering historic variability.\5\ Wyoming does 
not give the ``interfere with maintenance'' clause of section 
110(a)(2)(D)(i)(I) independent significance because its analysis did 
not evaluate the potential impact of Wyoming emissions on areas that 
are currently measuring clean data, but that may have issues 
maintaining that air quality.
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    \5\ 531 F.3d 896, 910-11 (D.C. Cir. 2008) (holding that the EPA 
must give ``independent significance'' to each prong of CAA section 
110(a)(2)(D)(i)(I)).
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    The EPA developed technical information and a related analysis to 
assist states with meeting section 110(a)(2)(D)(i)(I) requirements for 
the 2008 ozone NAAQS, and used this technical analysis to support the 
recently finalized Cross-State Air Pollution Rule Update for the 2008 
Ozone NAAQS (``CSAPR Update'').\6\ As explained below, this analysis 
supports the conclusions of WDEQ's analysis for prong 1 and contradicts 
the conclusions of WDEQ's analysis regarding prong 2.
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    \6\ 81 FR 74504 (Oct. 26, 2016).
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    In the technical analysis supporting the CSAPR Update, the EPA used 
detailed air quality analyses to determine where projected 
nonattainment or maintenance areas would be and whether emissions from 
an eastern state contribute to downwind air quality problems at those 
projected nonattainment or maintenance receptors.\7\ Specifically, the 
EPA determined whether a state's contributing emissions were at or 
above a specific threshold (i.e., one percent of the ozone NAAQS). If a 
state's contribution did not exceed the one percent threshold, the 
state was not considered ``linked'' to identified downwind 
nonattainment and maintenance receptors and was therefore not 
considered to significantly contribute to nonattainment or interfere 
with maintenance of the standard in those downwind areas. If a state's 
contribution was equal to or exceeded the one percent threshold, that 
state was considered ``linked'' to the downwind nonattainment or 
maintenance receptor(s) and the state's emissions were further 
evaluated, taking into account both air quality and cost 
considerations, to determine what, if any, emissions reductions might 
be necessary to address the state's obligation pursuant to CAA section 
110(a)(2)(D)(i)(I).
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    \7\ For purposes of the CSAPR Update, ``eastern'' states refer 
to all contiguous states east of the Rocky Mountains, specifically 
not including: Montana, Wyoming, Colorado and New Mexico.
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    As discussed in the CSAPR Update, the air quality modeling 
contained in the EPA's technical analysis (1) identified locations in 
the U.S. where the EPA anticipates nonattainment or maintenance issues 
in 2017 for the 2008 ozone NAAQS (these are identified as nonattainment 
and maintenance receptors), and (2) quantified the projected 
contributions from emissions from upwind states to downwind ozone 
concentrations at the receptors in 2017. See CSAPR Update at 81 FR 
74526. This modeling used the Comprehensive Air Quality Model with 
Extensions (CAMx version 6.11) to model the 2011 base year, and the 
2017 future base case emissions scenarios to identify projected 
nonattainment and maintenance sites with respect to the 2008 8-hour 
ozone NAAQS in 2017. The EPA used nationwide state-level ozone source 
apportionment modeling (the CAMx Ozone Source Apportionment Technology/
Anthropogenic Precursor Culpability Analysis technique) to quantify the 
contribution of 2017 base case nitrogen oxides (NOX) and 
volatile organic compounds (VOC) emissions from all sources in each 
state to the 2017 projected receptors. The air quality model runs were 
performed for a modeling domain that covers the 48 contiguous states in 
the U.S. and adjacent portions of Canada and Mexico. Id. at 81 FR 74526 
through 74527. The updated modeling data released to support the final 
CSAPR Update are the most up-to-date information the EPA has developed 
to inform our analysis of upwind state linkages to downwind air quality 
problems for the 2008 ozone NAAQS. See ``Air Quality Modeling Final 
Rule Technical Support Document for the Final CSAPR Update'' in the 
docket for this action for more details regarding the EPA's modeling 
analysis.
    Consistent with the framework established in the original CSAPR 
rulemaking, the EPA's technical analysis in support of the CSAPR Update 
applied a threshold of one percent of the 2008 ozone NAAQS of 75 ppb 
(0.75 ppb) to identify linkages between upwind states and the downwind 
nonattainment and maintenance receptors. See CSAPR Update at 81 FR 
74518 through 74519. The EPA considered eastern states whose 
contributions to a specific receptor meet or exceed the threshold 
``linked'' to that receptor and we analyzed these states further to 
determine if emissions reductions might be required from each state to 
address the downwind air quality problem. The EPA determined that one 
percent was an appropriate threshold to use in that analysis because 
there were important, even if relatively small, contributions to 
identified nonattainment and maintenance receptors from multiple upwind 
states. In response to commenters who advocated a higher or lower 
threshold than one percent, the EPA compiled the contribution modeling 
results for the CSAPR Update to analyze the impact of different 
possible thresholds for the eastern United States. The EPA's analysis 
showed that the one percent threshold captures a high percentage of the 
total pollution transport affecting downwind states. The EPA's analysis 
further showed that the application of a lower threshold would result 
in relatively modest increases in the overall percentage of ozone 
transport pollution captured, while the use of higher thresholds would 
result in a relatively large reduction in the overall percentage of 
ozone pollution transport captured relative to the levels captured at 
one percent at the majority of the receptors. Id.; See also Air Quality 
Modeling Final Rule Technical Support Document for the Final CSAPR 
Update, Appendix F, Analysis of Contribution Thresholds. This approach 
is consistent with the use of a one percent threshold to identify those 
states ``linked'' to air quality

[[Page 81715]]

problems with respect to the 1997 ozone NAAQS in the original CSAPR 
rulemaking, wherein the EPA noted that there are adverse health impacts 
associated with ambient ozone even at low levels. 76 FR 48208, 48236 
through 48237 (August 8, 2011).
    As to western states, the EPA noted in the CSAPR Update that there 
may be geographically specific factors to consider in evaluating 
interstate transport, and given the near-term 2017 implementation 
timeframe, the EPA focused the final CSAPR Update on eastern states. 
See CSAPR Update at 81 FR 74523. Consistent with our statements in the 
CSAPR Update, the EPA intends to address western states, like Wyoming, 
on a case-by-case basis.
    The EPA's air quality modeling as updated for the final CSAPR 
Update projects that for the Western U.S. (outside of California), 
there are no nonattainment receptors and only three maintenance 
receptors located in the Denver, Colorado area. Wyoming emissions are 
projected to contribute above one percent of the NAAQS at one of these 
receptors (the ``Douglas County maintenance receptor''; see Table 1, 
below). The modeling also shows that multiple upwind states would 
collectively contribute to the projected Douglas County maintenance 
receptor in Colorado. The EPA found that the contribution to ozone 
concentrations from all states upwind of the Douglas County maintenance 
receptor in Colorado is about 9.7 percent.\8\ Thus, the collective 
contribution of emissions from upwind states represents a large portion 
of the ozone concentrations at the projected Douglas County maintenance 
receptor in Colorado.
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    \8\ Please see the spreadsheet titled ``Final CSAPR Update--
Ozone Design Values & Contributions,'' in the docket for this 
action.
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    As noted, the Agency has historically found that the one percent 
threshold is appropriate for identifying interstate transport linkages 
for states collectively contributing to downwind ozone nonattainment or 
maintenance problems because that threshold captures a high percentage 
of the total pollution transport affecting downwind receptors. The EPA 
believes contribution from an individual state equal to or above one 
percent of the NAAQS could be considered significant where the 
collective contribution of emissions from one or more upwind states is 
responsible for a considerable portion of the downwind air quality 
problem regardless of where the receptor is geographically located. In 
this case, three states contributing to the Douglas County maintenance 
receptor, including Wyoming, contribute emissions greater than or equal 
to one percent of the 2008 ozone NAAQS. Given these data, the EPA is 
proposing to find that the one percent threshold is also appropriate to 
determine the linkage from Wyoming to the Douglas County maintenance 
receptor in Colorado with respect to the 2008 ozone NAAQS.
    The EPA is not necessarily determining that one percent of the 
NAAQS is always an appropriate threshold for identifying interstate 
transport linkages for all states in the West. For example, the EPA 
recently evaluated the impact of emissions from Arizona on two 
projected nonattainment receptors identified in California and 
concluded that even though Arizona's modeled contribution was greater 
than one percent of the 2008 ozone NAAQS, Arizona did not significantly 
contribute to nonattainment or interfere with maintenance at those 
receptors. See Proposed Rule, 81 FR 15202 (March 22, 2016); Final Rule, 
81 FR 31513 (May 19, 2016). The EPA evaluated the nature of the ozone 
nonattainment problem at the California receptors and determined that, 
unlike the receptors identified in the East and unlike the Douglas 
County maintenance receptor to which Wyoming contributes, only one 
state--Arizona--contributed above the one percent threshold to the 
California receptors and that the total contribution from all states 
linked to the receptors was negligible. See 81 FR at 15203. Considering 
this information, along with emissions inventories and emissions 
projections showing Arizona emissions decreasing over time, the EPA 
determined that Arizona had satisfied the requirements of section 
110(a)(2)(D)(i)(I) with respect to the 2008 ozone NAAQS. Id. 
Accordingly, where the facts and circumstances support a different 
conclusion, the EPA has not directly applied the one percent threshold 
to identify states which may significantly contribute to nonattainment 
or interfere with maintenance of the 2008 ozone NAAQS in other states.
    Likewise, the EPA is not determining that because Wyoming 
contributes above the one percent threshold, it is necessarily making a 
significant contribution that warrants further reductions in emissions. 
As noted above, the one percent threshold identifies a state as 
``linked,'' prompting further inquiry into whether the contributions 
are significant and whether there are cost-effective controls that can 
be employed. That inquiry with regard to Wyoming's SIP submittal is 
provided below.
    In summary, Table 1 shows the air quality modeling results from the 
final modeling in support of the CSAPR Update. The modeling indicates 
that Wyoming contributes emissions above the one percent threshold of 
0.75 ppb with respect to the Douglas County maintenance receptor in the 
Denver, Colorado area.

  Table 1--Maintenance Receptor With Wyoming Contribution Modeled Above
------------------------------------------------------------------------
                                                               Wyoming
                                                               modeled
         Monitor I.D.               State         County    contribution
                                                                (ppb)
------------------------------------------------------------------------
80350004.....................  Colorado......  Douglas....          1.18
------------------------------------------------------------------------

    Wyoming's largest contribution to any projected downwind 
maintenance-only site is 1.18 ppb, which is approximately 1.57% of the 
2008 ozone NAAQS of 75 ppb. Thus, the final modeling in support of the 
CSAPR Update indicates that the contributions from Wyoming are above 
the one percent threshold of 0.75 ppb with respect to the Douglas 
County maintenance receptor in the Denver, Colorado area, and the 
State's emissions require further evaluation, taking into account both 
air quality and cost considerations, to determine what, if any, 
emissions reductions might be necessary to address the State's emission 
reduction obligation pursuant to 110(a)(2)(D)(i)(I). However, WDEQ in 
its SIP submittal neither identified nor included any ozone or ozone 
precursor emission reduction measures that the EPA could evaluate to 
determine whether the state has fully addressed these transport 
impacts. Accordingly, the EPA cannot conclude that Wyoming's SIP 
contains sufficient provisions to prohibit emissions that will 
interfere with maintenance of the 2008 ozone NAAQS in the Denver, 
Colorado area.
    WDEQ's analysis regarding prong 1 is also incomplete as previously 
described, but the EPA's modeling indicates that Wyoming does not 
contribute above the one percent threshold to any nonattainment 
receptors. As discussed above, while the EPA is not necessarily 
determining that one percent of the NAAQS is always an appropriate 
threshold for identifying interstate transport linkages for all states 
in the West, this low level of contribution suggests that Wyoming does 
not contribute significantly to nonattainment of the 2008 ozone NAAQS 
in any other state. Thus, the EPA is proposing that the Wyoming SIP 
meets the 110(a)(2)(D)(i) prong 1 requirement for the 2008 ozone NAAQS.

[[Page 81716]]

    Based on WDEQ's SIP submittal and the EPA's most recent modeling, 
the EPA proposes to approve prong 1 and disapprove the prong 2 portion 
of the February 6, 2014, 2008 ozone NAAQS infrastructure submittal. The 
EPA is soliciting public comments on this proposed action and will 
consider public comments received during the comment period.

2008 Pb NAAQS

    WDEQ's analysis of potential interstate transport for the 2008 Pb 
NAAQS discussed the lack of sources with significant Pb emissions near 
the State's borders. As noted in our October 14, 2011 Infrastructure 
Guidance Memo, there is a sharp decrease in Pb concentrations, at least 
in the coarse fraction, as the distance from a Pb source increases. See 
``Guidance on Infrastructure SIP Elements Required Under Sections 
110(a)(1) and (2) for the 2008 Lead (Pb) National Ambient Air Quality 
Standards (NAAQS).'' October 14, 2011 at 8. For this reason, the EPA 
found that the requirements of subsection 110(a)(2)(D)(i)(I) (prongs 1 
and 2) could be satisfied through a state's assessment as to whether or 
not emissions from Pb sources located in close proximity to their state 
borders have emissions that impact the neighboring state such that they 
contribute significantly to nonattainment or interfere with maintenance 
in that state. Id. at 8. In that guidance document, the EPA further 
specified that any source appeared unlikely to contribute significantly 
to nonattainment unless it was located less than two miles from a state 
border and emitted at least 0.5 tons per year of Pb. WDEQ's 
110(a)(2)(D)(i)(I) analysis noted that there are no Pb sources within 
two miles of the State's borders. The EPA concurs with the Department's 
analysis and conclusion that no Wyoming sources have the combination of 
Pb emission levels and proximity to nearby nonattainment or maintenance 
areas to contribute significantly to nonattainment in or interfere with 
maintenance by other states for this NAAQS. Since Wyoming's SIP is 
therefore adequate to ensure that such impacts do not occur, the EPA is 
proposing to approve WDEQ's submittal with regard to the requirements 
of section 110(a)(2)(D)(i) prongs 1 and 2 for the 2008 Pb NAAQS.

2010 NO2 NAAQS

    Wyoming's 2010 NO2 transport analysis for elements 1 and 
2 of section 110(a)(2)(D)(i) describes how all NO2 monitors 
within the State and elsewhere in the U.S. showed no violations of the 
NO2 NAAQS. WDEQ asserted that because the entire country had 
been designated unclassifiable/attainment for the 2010 NO2 
NAAQS, Wyoming sources do not contribute significantly to nonattainment 
or interfere with maintenance of the NAAQS in other states. The 
Department's analysis is available in the docket for this action.
    The EPA does not agree with the Wyoming's reliance on area 
designations for purposes of determining whether the State has met the 
requirements of section 110(a)(2)(D)(i)(I) with respect to the 2010 
NO2 NAAQS. As noted above, the EPA has routinely interpreted 
the obligation to prohibit emissions that significantly contribute to 
nonattainment or interfere with maintenance of the NAAQS in downwind 
states to be independent of formal designations because exceedances can 
happen in any area. However, for the reasons explained below, the EPA 
concurs with the conclusion that emissions from the state do not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2010 NO2 NAAQS in any other state.
    Due to the State's limited technical analysis, the EPA evaluated 
NO2 monitoring data from Wyoming and surrounding states in 
reaching its conclusion. The EPA notes that the highest monitored 
NO2 design values in each state bordering or near Wyoming 
are significantly below the NAAQS (see Table 2).\9\ The EPA has 
determined that this information supports the State's contention that 
it does not significantly contribute to nonattainment or interfere with 
maintenance of the NO2 NAAQS. As shown in Table 2, the 
maximum design values in states bordering Wyoming are well below the 
2010 NO2 NAAQS. As the states near Wyoming are not only 
attaining, but also maintaining the NAAQS, there are no areas to which 
Wyoming could significantly contribute to nonattainment or interfere 
with maintenance of the 2010 NO2 NAAQS.
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    \9\ There is not an NO2 design value presented for 
Nebraska, as none is available in EPA's Air Trends or AirData Web 
sites.
    \10\ The design values for Montana and Utah were derived using 
EPA's AirData Web site at https://www3.epa.gov/airdata/ad_rep_mon.html. These are not official design values.

         Table 2--Highest Monitored 2010 NO2 NAAQS Design Values
------------------------------------------------------------------------
                                                2013-2015
                   State                      design value   % of  NAAQS
                                                  (ppb)       (100 ppb)
------------------------------------------------------------------------
Colorado...................................              72           72
Idaho......................................              43           43
Montana....................................         \10\ 29           29
South Dakota...............................              37           37
Utah.......................................              65           65
------------------------------------------------------------------------
* Source: https://www.epa.gov/air-trends/air-quality-design-values.

    In addition to the monitored levels of NO2 in states 
near Wyoming being well below the NAAQS, Wyoming's highest official 
design value from 2013-2015 was also significantly below this NAAQS-49 
ppb, compared to the NAAQS level of 100 ppb.\11\
---------------------------------------------------------------------------

    \11\ https://www.epa.gov/air-trends/air-quality-design-values.
---------------------------------------------------------------------------

    Based on all of these factors, EPA concurs with the State's 
conclusion that Wyoming does not contribute significantly to 
nonattainment or interfere with maintenance of the 2010 NO2 
NAAQS in other states. The EPA is therefore proposing to determine that 
Wyoming's SIP includes adequate provisions to prohibit sources or other 
emission activities within the State from emitting NO2 in 
amounts that will contribute significantly to nonattainment in or 
interfere with maintenance by any other state with respect to the 
NO2 NAAQS.

IV. Evaluation of Interference With Measures To Protect Visibility

State Submissions

    In Wyoming's 2008 ozone, 2010 SO2, 2010 NO2 
and 2012 PM2.5 NAAQS infrastructure certifications, the 
Department pointed to both its Regional Haze SIP and Wyoming Air 
Quality Standards and Regulations (WAQSR) Chapter 9, Section 2, 
``Visibility,'' to certify that the State meets the visibility 
requirements of section 110(a)(2)(D)(i)(II) (prong 4). As explained 
below, this information is relevant in determining whether Wyoming's 
SIP will achieve the emission reductions that the Western Regional Air 
Partnership (WRAP) states mutually agreed are necessary to avoid 
interstate visibility impacts in Class I areas. See ``Guidance on 
Infrastructure State Implementation Plan (SIP) Elements under Clean Air 
Act Sections 110(a)(1) and (2),'' September 13, 2013, (``2013 
Guidance'') at 34.
    WDEQ addressed visibility for the 2008 Pb NAAQS by pointing to the 
lack of significant sources of Pb in Wyoming near the State's border. 
Id. at 33. The

[[Page 81717]]

State did not point to any visibility-related state regulations in its 
2006 PM2.5, certification, but generally indicated that they 
met this requirement.

Wyoming's Regional Haze SIP

    As stated in the EPA's 2013 Guidance, ``[o]ne way in which prong 4 
may be satisfied for any relevant NAAQS is through an air agency's 
confirmation in its infrastructure SIP submission that it has an 
approved regional haze SIP that fully meets the requirements of 40 CFR 
51.308 or 51.309. 40 CFR 51.308 and 51.309 specifically require that a 
state participating in a regional planning process include all measures 
needed to achieve its apportionment of emission reduction obligations 
agreed upon through that process.'' Id. at 33.
    On January 12, 2011 and April 19, 2012, Wyoming submitted to the 
EPA SIP revisions to address the requirements of the regional haze 
program. The EPA approved Wyoming's April 19, 2012 submittal and 
partially approved Wyoming's January 12, 2011 submittal in a final 
action published December 12, 2012. 77 FR 73926. This included EPA 
approval of Wyoming's BART alternative for SO2, which relied 
on the State's participation in the backstop SO2 trading 
program under 40 CFR 51.309.\12\ In a separate action, the EPA 
partially approved and partially disapproved the remainder of Wyoming's 
January 12, 2011 SIP revision. 79 FR 5032 (Jan. 30, 2014). In that 
action, the EPA disapproved the following portions of the submittal: 
Wyoming's NOX Best Available Retrofit Technology (BART) 
determinations for five units at three facilities; the State's 
reasonable progress goals; monitoring, recordkeeping and reporting 
requirements; portions of the long term strategy, and; the provisions 
necessary to review reasonably attributable visibility improvement. Id. 
at 5038. The EPA also promulgated a final federal implementation plan 
(FIP) to address these deficiencies. Id.
---------------------------------------------------------------------------

    \12\ Wyoming's ``Western Backstop Sulfur Dioxide Trading 
Program'' can be found in Wyoming Air Quality Standards and 
Regulations (WAQSR) Chapter 14, Section 2.
---------------------------------------------------------------------------

EPA's Assessment

    The 2013 Guidance states that section 110(a)(2)(D)(i)(II)'s prong 4 
requirements can be satisfied by approved SIP provisions that the EPA 
has found to adequately address a state's contribution to visibility 
impairment in other states. The EPA interprets prong 4 to be pollutant-
specific, such that the infrastructure SIP submission need only address 
the potential for interference with protection of visibility caused by 
the pollutant (including precursors) to which the new or revised NAAQS 
applies. See 2013 Guidance at 33.
    The 2013 Guidance lays out two ways in which a state's 
infrastructure SIP submittal may satisfy prong 4. As explained above, 
one way is through a state's confirmation in its infrastructure SIP 
submittal that it has an EPA approved regional haze SIP in place. 
Alternatively, in the absence of a fully approved regional haze SIP, a 
state can make a demonstration in its infrastructure SIP submittal that 
emissions within its jurisdiction do not interfere with other states' 
plans to protect visibility. Such a submittal should point to measures 
in the state's SIP that limit visibility-impairing pollutants and 
ensure that the resulting reductions conform to any mutually agreed 
emission reductions under the relevant regional haze regional planning 
organization (RPO) process.\13\
---------------------------------------------------------------------------

    \13\ See id. at 34, and also 76 FR 22036 (April 20, 2011) 
containing EPA's approval of the visibility requirement of 
110(a)(2)(D)(i)(II) based on a demonstration by Colorado that did 
not rely on the Colorado Regional Haze SIP.
---------------------------------------------------------------------------

    WDEQ worked through its RPO, the WRAP, to develop strategies to 
address regional haze. To help states in establishing reasonable 
progress goals for improving visibility in Class I areas, the WRAP 
modeled future visibility conditions based on the mutually agreed 
emissions reductions from each state. The WRAP states then relied on 
this modeling in setting their respective reasonable progress goals. As 
a result, we consider emissions reductions from measures in Wyoming's 
SIP that conform with the level of emission reductions the State agreed 
to include in the WRAP modeling to meet the visibility requirement of 
CAA section 110(a)(2)(D)(i)(II).
    With regard to the 2010 SO2 NAAQS, the EPA proposes to 
find that the State's implementation of the Western Backstop Sulfur 
Dioxide Trading Program and the agreed upon SO2 reductions 
achieved through that program sufficient to meet the requirements of 
prong 4.\14\ Under 40 CFR 51.309, certain states, including Wyoming, 
can satisfy their SO2 BART requirements by adopting an 
alternative program consisting of SO2 emission milestones 
and a backstop trading program. See 40 CFR 51.309. Wyoming Air Quality 
Standards and Regulations (WAQSR) Chapter 14, section 2 implements the 
backstop trading program provisions and the EPA has approved the 
State's rules, including the SO2 reduction milestones, as 
satisfying its regional haze SO2 obligations. 77 FR 73926 
(Dec. 12, 2012). Wyoming's SIP thus contains measures requiring 
reductions of SO2 consistent with what the State agreed to 
achieve under the WRAP process in order to protect visibility. As a 
result, the EPA is proposing to approve 110(a)(2)(D)(i)(II) prong 4 for 
the 2010 SO2 NAAQS.
---------------------------------------------------------------------------

    \14\ Specifically, the State is required to reach its 
``emissions milestone'' for this program by keeping its 
SO2 emissions below 141,849 tons/SO2 in 2018 
and each year thereafter.
---------------------------------------------------------------------------

    The EPA is also proposing to approve Wyoming's prong 4 SIP 
submittal for the 2008 Pb NAAQS. The EPA has found that significant 
impacts from Pb emissions from stationary sources are expected to be 
limited to short distances from the source. The State noted that it 
does not have any major sources of Pb located near any bordering state. 
Further, when evaluating the extent to which Pb could impact 
visibility, the EPA has found Pb-related visibility impacts 
insignificant (e.g., less than 0.10 percent). See 2013 Guidance, at 33. 
The EPA proposes to approve prong 4 for the 2008 Pb NAAQS based on 
Wyoming's conclusion that it does not have any significant sources of 
lead emissions near another state's border and that it, therefore, does 
not have emissions of Pb that would interfere with the requirements of 
section 110(a)(2)(D)(i)(II) with respect to visibility.
    The EPA is proposing to disapprove Wyoming's prong 4 infrastructure 
SIP submittals for the 2006 PM2.5, 2008 ozone, 2010 
NO2, and 2012 PM2.5 NAAQS. The EPA's disapproval 
of Wyoming's NOX BART determination in our January 30, 2014 
final rulemaking included the specific disapproval of the NOx control 
measures the State submitted for PacifiCorp Dave Johnston Unit 3, 
PacifiCorp Wyodak Unit 1, and Basin Electric Laramie River Units 1, 2 
and 3. See 79 FR 5038.
    As noted, Wyoming referenced both its Regional Haze SIP and WAQSR 
Chapter 9, Section 2 as justification for the approvability of prong 4 
for the 2008 ozone, 2010 NO2 and 2012 PM2.5 
NAAQS. Because the Department did not provide an alternative 
demonstration that its SIP contains measures to limit NOX 
emissions in accordance with the emission reductions it agreed to under 
the WRAP,\15\ the EPA's disapproval of portions of Wyoming's NOx BART 
determination means that Wyoming's SIP does not include measures needed 
to ensure that its emissions will not

[[Page 81718]]

interfere with other states' plans to protect visibility from the 
effects of NAAQS pollutants impacted by NOx. Specifically, NOx is a 
precursor of PM2.5 and ozone, and is also a term which 
refers to both NO (nitrogen oxide) and NO2. The EPA is 
therefore proposing to disapprove prong 4 of Wyoming's infrastructure 
certifications with regard to the 2006 PM2.5, 2008 ozone, 
2010 NO2 and 2012 PM2.5 NAAQS.
---------------------------------------------------------------------------

    \15\ The Visibility section of WAQSR Chapter 9, Section 2 does 
not address NOx emissions reductions.
---------------------------------------------------------------------------

    If the EPA disapproves an infrastructure SIP submission for prong 
4, as we are proposing for the 2006 PM2.5, 2008 ozone, 2010 
NO2 and 2012 PM2.5 NAAQS, a FIP obligation will 
be created. However, as noted previously, the EPA has promulgated a FIP 
for Wyoming that corrects all regional haze SIP deficiencies. 79 FR 
5032. Therefore, there will be no additional practical consequences 
from the disapproval for WDEQ, the sources within its jurisdiction, or 
the EPA, and the EPA will not be required to take further action with 
respect to these prong 4 disapprovals, if finalized, because the FIP 
already in place would satisfy the requirements with respect to prong 
4. See 2013 Guidance at 34-35. Additionally, since the infrastructure 
SIP submission is not required in response to a SIP call under CAA 
section 110(k)(5), mandatory sanctions under CAA section 179 would not 
apply because the deficiencies are not with respect to a submission 
that is required under CAA title I part D. Id.

V. Proposed Action

    The EPA is proposing to approve CAA section 110(a)(2)(D)(i)(I) 
prongs 1, 2 and 4 for the 2008 Pb NAAQS, prong 1 for the 2008 ozone 
NAAQS, and prong 4 for the 2010 SO2 NAAQS, as shown in Table 
3, below. The EPA is also proposing to disapprove prong 4 for the 2006 
PM2.5, 2008 ozone, 2010 NO2 and 2012 
PM2.5 NAAQS, and prong 2 for the 2008 ozone NAAQS, as shown 
in Table 4. The EPA is soliciting public comments on this proposed 
action and will consider public comments received during the comment 
period.

  Table 3--List of Wyoming Interstate Transport Prongs That the EPA Is
                          Proposing To Approve
------------------------------------------------------------------------
                            Proposed approval
-------------------------------------------------------------------------
February 6, 2014 submittal--2008 Ozone NAAQS: (D)(i)(I) prong 1.
October 12, 2011 submittal--2008 Pb NAAQS: (D)(i)(I) prongs 1 and 2,
 (D)(i)(II) prong 4.
January 24, 2014 submittal--2010 NO2 NAAQS: (D)(i)(I) prongs 1 and 2.
March 6, 2015 submittal--2010 SO2 NAAQS:
(D)(i)(II) prong 4.
------------------------------------------------------------------------

  Table 4--List of Wyoming Interstate Transport Prongs That the EPA Is
                         Proposing To Disapprove
------------------------------------------------------------------------
                          Proposed disapproval
-------------------------------------------------------------------------
August 19, 2011 submittal--2006 PM2.5 NAAQS:
(D)(i)(II) prong 4.
February 6, 2014 submittal--2008 Ozone NAAQS:
(D)(i)(I) prong 2, (D)(i)(II) prong 4.
January 24, 2014 submittal--2010 NO2 NAAQS:
(D)(i)(II) prong 4.
June 24, 2016 submittal--2012 PM2.5 NAAQS:
(D)(i)(II) prong 4.
------------------------------------------------------------------------

VI. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve state actions, 
provided that they meet the criteria of the Clean Air Act. Accordingly, 
this proposed action merely proposes approval of some state law as 
meeting federal requirements and proposes disapproval of other state 
law because it does not meet federal requirements; this proposed action 
does not propose additional requirements beyond those imposed by state 
law. For that reason, this proposed action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide the EPA with the discretionary authority 
to address, as appropriate, disproportionate human health or 
environmental effects, using practicable and legally permissible 
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, 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: November 9, 2016.
Shaun L. McGrath,
Regional Administrator, Region 8.
[FR Doc. 2016-27672 Filed 11-17-16; 8:45 am]
BILLING CODE 6560-50-P