[Federal Register Volume 75, Number 176 (Monday, September 13, 2010)]
[Proposed Rules]
[Pages 55494-55503]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-22773]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R10-OAR-2010-0669; FRL-9200-5]
Approval and Promulgation of Implementation Plans; Idaho;
Interstate Transport of Pollution
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: EPA is proposing to approve a State Implementation Plan (SIP)
revision submitted by the State of Idaho for the purpose of addressing
the ``good neighbor'' provisions of the Clean Air Act (CAA) section
110(a)(2)(D)(i) for the 1997 8-hour ozone National Ambient Air Quality
Standards (NAAQS or standards) and the 1997 PM2.5 NAAQS.
This SIP revision addresses the requirement that the State of Idaho's
SIP have adequate provisions to prohibit air emissions from adversely
affecting another state's air quality through interstate transport. In
this action, EPA is proposing to approve the Idaho Interstate Transport
SIP provisions that address the requirement of section 110(a)(2)(D)(i)
that emissions from Idaho sources do not significantly contribute to
nonattainment of the 1997 8-hour ozone NAAQS and the 1997
PM2.5 NAAQS in any other state, interfere with maintenance
of the 1997 8-hour ozone NAAQS and the 1997 PM2.5 NAAQS in
any other state, and interfere with measures required in the SIP of any
other state under part C of subchapter I of the CAA to prevent
significant deterioration of air quality. This action is being taken
under section 110 and part C of subchapter I of the Clean Air Act (the
Act or CAA).
DATES: Written comments must be received on or before October 13, 2010.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2008-0391, by one of the following methods:
A. http://www.regulations.gov. Follow the online instructions for
submitting comments.
B. E-Mail: [email protected].
C. Mail: Donna Deneen, U.S. Environmental Protection Agency, Region
10, 1200 Sixth Avenue, Suite 900, Mail Stop: AWT-107, Seattle, WA
98101.
D. Hand Delivery: U.S. Environmental Protection Agency, Region 10,
Attn: Donna Deneen (AWT-107), 1200 Sixth Avenue, Suite 900, Seattle,
Washington 98101, 9th Floor. Such deliveries are only accepted during
normal hours of operation, and special arrangements should be made for
deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-R10-OAR-
2010-0669. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov or email. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an email comment directly to EPA without
going through http://www.regulations.gov, your email address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of you comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses.
Docket: All documents in the electronic docket are listed in the
www.regulations.gov index. Although listed in the index, some
information, i.e., CBI or other information whose disclosure is
restricted by statute, is not publicly available. Certain other
material, such as copyrighted material, is not placed on the Internet
and will be publicly available only in hard copy form. Publicly
available docket materials are available either electronically in
http://www.regulations.gov or in hard copy during normal business hours
at the Office of Air, Waste and Toxics, U.S. Environmental Protection
Agency, Region 10, 1200 Sixth Avenue, Suite 900, Seattle, Washington
98101.
FOR FURTHER INFORMATION CONTACT: Donna Deneen, (206) 553-6706 or
[email protected].
SUPPLEMENTARY INFORMATION: Throughout this notice, the words ``we'',
``us'', or ``our'' means the Environmental Protection Agency (EPA).
Table of Contents
I. What proposed action is EPA taking?
II. What is a SIP?
III. What is the background for this proposed action?
IV. What is EPA's evaluation of the State's submission?
A. EPA's Evaluation of Significant Contribution to Nonattainment
1. 1997 PM2.5 Nonattainment Areas and Monitoring Data
in States Surrounding Idaho
2. 1997 8-Hour Ozone Nonattainment Areas and Monitoring Data in
States Surrounding Idaho
3. State Regulatory Provisions
4. Conclusion Regarding Significant Contribution to
Nonattainment
B. EPA's Evaluation of Interference With Maintenance
1. Background
2. Idaho's Interference With Maintenance Demonstration
3. EPA's Supplemental Analysis
4. Conclusion Regarding Interference With Maintenance
C. EPA's Evaluation of Interference With PSD Measures in Other
States
V. Proposed Action
VI. Statutory and Executive Order Reviews
I. What proposed action is EPA taking?
EPA is proposing to approve a portion of Idaho's Interstate
Transport State Implementation Plan (SIP) revision for the 1997 8-hour
ozone and 1997 PM2.5 NAAQS submitted by the Idaho Department
of Quality (IDEQ) on June 28, 2010. Specifically, we are proposing to
approve the portion of the plan that addresses the following elements
of
[[Page 55495]]
CAA section 110(a)(2)(D)(i): (1) Significant contribution to
nonattainment of these NAAQS in any other state, (2) interference with
maintenance of these NAAQS by any other state, and (3) interference
with any other state's required measures to prevent significant
deterioration (PSD) of its air quality with respect to these NAAQS.
IDEQ addressed element (4), interference with any other state's
required measures to protect visibility, by referring to its Regional
Haze SIP, which will be submitted separately. EPA will take action on
the visibility element in a separate action. EPA will also take action
on the portion of Idaho's SIP that addresses the 2006 PM2.5
NAAQS \1\ in a separate action.
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\1\ The PM2.5 standard was revised in 2006. See
``National Ambient Air Quality Standards for Particulate Matter,''
at 71 FR 61144, (October 17, 2006).
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Idaho's June 28, 2010, SIP revision replaces a previously submitted
section 110(a)(2)(D)(i) SIP revision submitted by IDEQ on January 30,
2007, for the 1997 PM2.5 standards. EPA proposed approval of
that SIP revision on June 26, 2007 (72 FR 35022), but did not take
final action. When Idaho submitted its June 28, 2010, SIP revision,
Idaho requested that EPA replace the SIP submitted on January 30, 2007,
with the revised SIP submitted on June 28, 2010. In light of Idaho's
resubmittal of its Interstate Transport SIP, EPA is withdrawing its
June 26, 2007, proposal and is issuing this proposal to approve Idaho's
June 28, 2010, SIP revision in its place. Accordingly, EPA will not be
responding to comments on the June 26, 2007, proposal. Any person who
wishes to comment on EPA's proposed approval of Idaho's SIP revision
addressing section 110(a)(2)(D)(i) for the 1997 8-hour ozone and 1997
PM2.5 standards should do so at this time.
II. What is a SIP?
Section 110(a) of the CAA requires each state to develop a plan
that provides for the implementation, maintenance, and enforcement of
the NAAQS. EPA establishes NAAQS under section 109 of the CAA.
Currently, the NAAQS address six criteria pollutants: Carbon monoxide,
nitrogen dioxide, ozone, lead, particulate matter, and sulfur dioxide.
The plan developed by a state is referred to as the SIP. The
content of the SIP is specified in section 110 of the CAA, other
provisions of the CAA, and applicable regulations. SIPs can be
extensive, containing state regulations or other enforceable measures
and various types of supporting information, such as emissions
inventories, monitoring networks, and modeling demonstrations.
A primary purpose of the SIP is to provide the air pollution
regulations, control strategies, and other means or techniques
developed by the state to ensure that the ambient air within that state
meets the NAAQS. However, another important aspect of the SIP is to
ensure that emissions from within the state do not have certain
prohibited impacts upon the ambient air in other states through
interstate transport of pollutants. This SIP requirement is specified
in section 110(a)(2)(D). Pursuant to that provision, each state's SIP
must contain provisions adequate to prevent emissions that
significantly contribute to violations of the NAAQS in any other state,
interfere with maintenance in any other state, interfere with any other
state's required measures to prevent significant deterioration of its
air quality, and interfere with any other state's required measures to
protect visibility.
States are required to update or revise SIPs under certain
circumstances. One such circumstance is EPA's promulgation of a new or
revised NAAQS. Each state must submit these revisions to EPA for
approval and incorporation into the federally-enforceable SIP.
III. What is the background for this proposed action?
On July 18, 1997, EPA promulgated new standards for 8-hour ozone
and fine particulate matter (PM2.5). This action is being
taken in response to the promulgation of the 1997 8-hour ozone NAAQS
and 1997 PM2.5 NAAQS. This action does not address the
requirements of the 2006 PM2.5 NAAQS or the 2008 8-hour
ozone NAAQS; those standards will be addressed in a future action.
Section 110(a)(1) of the CAA requires states to submit SIPs to
address a new or revised NAAQS within three years after promulgation of
such standards, or within such shorter period as EPA may prescribe.
Section 110(a)(2) lists the elements that such new SIPs must address,
as applicable, including section 110(a)(2)(D)(i) which pertains to
interstate transport of certain emissions. On August 15, 2006, EPA
issued its ``Guidance for State Implementation Plan (SIP) Submission to
Meet Current Outstanding Obligations Under Section 110(a)(2)(D)(i) for
the 8-hour ozone and PM2.5 National Ambient Air Quality
Standards'' (2006 Guidance) for SIP submissions that states should use
to address the requirements of section 110(a)(2)(D)(i). EPA developed
this guidance to make recommendations to states for making submissions
to meet the requirements of section 110(a)(2)(D) for the 1997 8-hour
ozone standards and 1997 PM2.5 standards.
On June 28, 2010, we received a SIP revision from the State of
Idaho to address the requirements of section 110(a)(2)(D)(i) for the
1997 8-hour ozone NAAQS and 1997 PM2.5 NAAQS. The ``good
neighbor'' provisions in section 110(a)(2)(D)(i) require each state to
submit a SIP that prohibits emissions that adversely affect another
state in the ways contemplated in the statute. Section 110(a)(2)(D)(i)
identifies four distinct elements related to the evaluation of impacts
of interstate transport of air pollutants. In this rulemaking EPA is
addressing the first three elements: (1) Significant contribution to
nonattainment of these NAAQS in any other state, (2) interference with
maintenance of these NAAQS by any other state, and (3) interference
with any other state's required measures to prevent significant
deterioration (PSD) of its air quality with respect to these NAAQS.
Idaho asserts in its SIP submission that its current SIP is adequate to
prevent such contribution and interference, and thus no additional
controls or revisions are needed with respect to the 1997 8-hour ozone
NAAQS and 1997 PM2.5 NAAQS. EPA is proposing to find that
Idaho's Interstate Transport SIP provisions addressing elements (1),
(2), and (3) of section 110(a)(2)(D)(i) are consistent with the
requirements of the CAA.
IV. What is EPA's evaluation of the State's submission?
A. EPA's Evaluation of Significant Contribution to Nonattainment
Section 110(a)(2)(D)(i) provides that EPA cannot approve a state's
SIP for a new or revised NAAQS unless it contains adequate measures to
prohibit emissions from sources within the state from contributing
significantly to nonattainment of the NAAQS in another state. EPA's
August 2006 Guidance concerning section 110(a)(2)(D)(i) recommended
various methods by which states might evaluate whether or not their
emissions significantly contribute to nonattainment of the 1997 8-hour
ozone or the 1997 PM2.5 NAAQS in another state. Among other
methods, EPA recommended consideration of available EPA modeling
conducted in conjunction with the Clean Air Interstate Rule (CAIR),\2\
or in the
[[Page 55496]]
absence of such EPA modeling, consideration of other information such
as the amount of emissions, the geographic location of violating areas,
meteorological data, or various other forms of information that would
be relevant to assessing the likelihood of significant contribution to
violations of the NAAQS in another state. The assessment of significant
contribution to nonattainment is not restricted to impacts upon areas
that are formally designated nonattainment. Consistent with EPA's
approach in CAIR and in the Transport Rule Proposal, this impact must
be evaluated with respect to monitors showing a violation of the NAAQS
(70 FR 25172, May 12, 2005, and 63 FR 57371, October 27, 1998).\3\
Furthermore, although relevant information other than modeling may be
considered in assessing the likelihood of significant contribution to
nonattainment of the 8-hour ozone or PM2.5 NAAQS in another
state, EPA notes that no single piece of information is by itself
dispositive of the issue. Instead, the total weight of all the evidence
taken together is used to evaluate significant contributions to
violations of the 1997 8-hour ozone or 1997 PM2.5 NAAQS in
another state.
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\2\ See ``Rule to Reduce Interstate Transport of Fine
Particulate Matter and Ozone (Clean Air Interstate Rule); Revisions
to Acid Rain Program; Revisions to the NOX SIP Call;
Final Rule,'' at 70 FR 25162 at 25263-69 (May 12, 2005).
\3\ See Section B(1) of this notice for more history on CAIR and
the Transport Rule Proposal. EPA has taken a similar approach in the
recent Transport Rule Proposal discussed below.
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This proposed approval addresses the significant contribution
element for the 1997 8-hour ozone and 1997 PM2.5 NAAQS in
several ways. It takes into account Idaho's SIP submission that
addressed the significant contribution element for the 1997 8-hour
ozone and 1997 PM2.5 NAAQS by evaluating potential impacts
from Idaho sources on 1997 8-hour ozone and 1997 PM2.5
nonattainment areas in surrounding states based on a review of
meteorological and other characteristics of those areas. The State's
SIP submission also relied on provisions in its air quality regulations
that address Idaho's authority to address nonattainment issues. In
addition to the arguments presented by Idaho to support its
demonstration that its SIP satisfies the significant contribution
element of the CAA, EPA has supplemented its analysis with monitoring
data and other information related to the 1997 PM2.5
nonattainment areas identified by Idaho, and has also provided
monitoring data and other information for the surrounding states
generally. Our evaluation below regarding how Idaho's SIP satisfies the
significant contribution element of the CAA is organized as follows.
Section 1 addresses the 1997 PM2.5 nonattainment areas in
surrounding states (including PM2.5 monitoring data for
those nonattainment areas) and PM2.5 monitoring data
generally for surrounding states. Section 2 addresses the 1997 8-hour
ozone nonattainment areas in surrounding states (including ozone
monitoring data for those nonattainment areas) and ozone monitoring
data generally for surrounding states. Section 3 addresses Idaho's air
quality regulations for both the 1997 8-hour ozone and 1997
PM2.5 NAAQS which pertain to Idaho's authority to address
nonattainment issues.
1. 1997 PM2.5 Nonattainment Areas and Monitoring Data in
States Surrounding Idaho
1997 PM2.5 Nonattainment Areas
To address whether Idaho sources significantly contribute to
nonattainment of the 1997 PM2.5 NAAQS in another state,
Idaho reviewed meteorological and other characteristics of any areas
designated nonattainment for the 1997 PM2.5 NAAQS in
surrounding states to determine whether transport of emissions from
Idaho significantly contribute to nonattainment in those areas. Relying
primarily on technical support documents (TSDs) prepared for EPA's 8-
hour ozone and PM2.5 NAAQS nonattainment designations, Idaho
noted that air stagnation is cited as a major contributing factor to
nonattainment in those areas and that under air stagnation conditions
there is little to no transport of pollutants over long distances.
Idaho also noted that none of the TSDs identified Idaho sources as
significant contributors to any 1997 PM2.5 nonattainment
areas.
As a part of EPA's analysis of whether or not PM2.5
emissions from Idaho significantly contribute to nonattainment in
another state, EPA reviewed and analyzed information available for the
1997 PM2.5 nonattainment areas in states surrounding Idaho.
Although significant contribution must be measured not just against
nonattainment areas, but also against areas with monitors showing
violations of the NAAQS, nonattainment areas are a convenient starting
point for the analysis. For the 1997 PM2.5 NAAQS, Libby, in
Lincoln County, Montana is the only designated nonattainment area in
any state bordering Idaho.\4\ In 2005, EPA designated this area
nonattainment for the 1997 annual PM2.5 NAAQS. 70 FR 944
(January 5, 2005) and 40 CFR 81.327.
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\4\ Libby is in a narrow valley surrounded by mountains 4,000
feet higher than the town. The Rocky Mountain Range to the west of
Libby (and east of the Idaho border) reaches summit elevations of
12,000 feet with most summit elevations between 6000 and 7000 feet
that act as a barrier to air movement between Idaho and Montana.
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A number of factors provide evidence that Idaho emissions do not
significantly contribute to past violations of the 1997 annual
PM2.5 standards in Libby, Montana. First, in the process of
designating Libby nonattainment for both the 1997 PM2.5
NAAQS and the 2006 PM2.5 NAAQS, EPA noted the predominantly
local origins of PM2.5 nonattainment in Libby.5 6
Residential wood-burning stoves during the winter-time, when frequent
and persistent temperature inversions occurred, were specifically
identified as a key source of PM emissions.
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\5\ ``Technical Support for State and Tribal Air Quality Fine
Particle (PM2.5) Designations,'' (for Montana) Chapter 6,
pp. 347-352, December 2004.
\6\ ``Technical Support for State and Tribal Air Quality Fine
Particle (PM2.5) Designations,'' (for Montana) Chapter
4.8.1, pp. 1-15, December 2008.
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Although local sources were believed to predominate in the Libby
nonattainment area, EPA specifically considered in the 1997
PM2.5 designation process whether Idaho sources contributed
to PM2.5 nonattainment in Libby. While a nonattainment
designation analysis is not the same inquiry that is required under CAA
section 110(a)(2)(D), some of the factual findings from that effort are
helpful in understanding the potential for interstate transport of
pollutants in the Libby area. If there were an area in Idaho from which
significant contribution would be most likely, it would arguably be
from Bonner and Boundary counties in Idaho. These counties are located
in Idaho's panhandle and are the only Idaho counties located to the
west of the Libby nonattainment area. Transport winds generally flow
across Idaho from west to east, and Libby is directly east of Bonner
and Boundary counties. In the process of designating Libby
nonattainment for the 1997 PM2.5 NAAQS, EPA concluded that
there was insufficient data to justify including those two Idaho
counties (or any portion thereof) in the Libby nonattainment area.\7\
Monitoring data from 1999 through 2009 show that PM2.5
design value levels for both Idaho counties have remained below 30
[mu]g/m\3\ or 85 percent of the 1997 PM2.5 NAAQS. This is
consistent with a conclusion that local sources in Libby were a key
[[Page 55497]]
contributor to the area's past nonattainment. Although the predominance
of local sources does not rule out the possibility of impacts from
interstate transport, this fact taken in conjunction with the
mountainous topography of the area, supports a conclusion that Idaho
emissions do not contribute significantly to the past NAAQS violations
in Libby.
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\7\ ``Technical Support for State and Tribal Air Quality Fine
Particle (PM2.5) Designations,'' Chapter 6, pp. 347-352,
December 2004.
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Second, monitoring data from 1999 through 2009 from areas outside
of Libby in Montana support a determination that Idaho does not
significantly contribute to nonattainment in Libby. At all other sites
in Montana, annual PM2.5 design value levels have remained
below the 15 [mu]g/m\3\ nonattainment threshold. Annual
PM2.5 design values for this period for most of these
monitors remained at levels equal to, or less than, two-thirds of the
1997 NAAQS. Even the three highest design values at these monitors were
20 percent below the level of the annual standard.\8\ The lower
PM2.5 levels elsewhere in Montana are evidence that local
sources, and not interstate transport, are key contributors to past
nonattainment in Libby.
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\8\ In 2001, 2002 and 2006, design values for two monitors in
Missoula County were 11.1, 11.4 and 11.8 [mu]g/m\3\. Computed from
AQS monitoring data. 75 FR 16028 (March 31, 2010).
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Monitoring data from Idaho likewise supports a finding that Idaho
does not significantly contribute to nonattainment elsewhere. In Idaho,
annual PM2.5 design values from 1999 through 2009 have
remained below the 1997 NAAQS. The comparatively lower levels of
PM2.5 monitored throughout Idaho and elsewhere in Montana
are consistent with a conclusion that local sources, and not sources in
another state, are the predominant source of PM2.5 levels in
Libby. The fact that monitors located in Idaho have not registered
violations of the 1997 PM2.5 NAAQS does not conclusively
establish that emissions from Idaho could not contribute in the
aggregate to violations in Libby, but this fact combined with the
localized nature of the violations in Libby supports the conclusion
that sources in Idaho do not significantly contribute to
PM2.5 levels in Libby. By 2007-2008, the annual
PM2.5 design values for the Libby nonattainment area itself
fell below the levels of the NAAQS. This reduction has been attributed
to an effective wood stove replacement program that decreased
PM2.5 emissions by approximately 59 percent.\9\ In other
words, even if emissions from Idaho sources were reaching Libby, they
would not significantly contribute to violations of the 1997
PM2.5 NAAQS because monitoring data demonstrate that Libby
is not violating the 1997 PM2.5 NAAQS.
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\9\ State of Montana, Department of Environmental Quality,
``State Implementation Plan-Libby Annual PM2.5 Control
Plan,'' submitted to EPA April 1, 2008.
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Finally, EPA's conclusion that emissions from Idaho do not
significantly contribute to nonattainment in Libby, Montana, is further
supported by a modeling analysis for monitors in the western United
States.\10\ This modeling concludes that in 2012 the average design
values in Lincoln County, Montana for PM2.5 will be below
the threshold for consideration as a nonattainment receptor.
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\10\ See Section B of this notice for a more complete discussion
of the Transport Rule Proposal and EPA's modeling analysis of the
western states.
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The next closest 1997 PM2.5 nonattainment area to the
state of Idaho is the San Joaquin Valley in California.\11\ This
nonattainment area is over 300 miles southwest of the closest point on
the Idaho border and is on the other side of the Sierra Nevada
Mountains. This 400 mile long north-south range of mountains has peaks
of more than 14,000 feet which act as a natural barrier to air movement
between Idaho and California. In addition, San Joaquin Valley,
California, is not in the predominant direction of winds from Idaho.
Transport winds across Idaho generally flow from west to east, and not
toward the southwest. Given the relatively long distance between Idaho
and the San Joaquin Valley, the intervening mountainous topography, and
the general west-to-east direction of transport winds across Idaho, EPA
believes it is reasonable to conclude that Idaho sources do not
significantly contribute to nonattainment of the 1997 PM2.5
NAAQS in the San Joaquin Valley.
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\11\ In 2005, EPA designated this area nonattainment for
violations of the 1997 and annual PM2.5 NAAQS. 70 FR 944
(January 5, 2005), and 40 CFR 81.305.
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PM2.5 Monitoring Data in Other Areas of Surrounding States
As mentioned above, EPA considers not only significant contribution
to designated nonattainment areas, but also significant contribution to
areas with monitors showing violations of the NAAQS. A review of the
most recent three years of monitoring data in EPA's Air Quality System
(AQS) for the bordering states of Washington, Oregon, Nevada, Utah,
Wyoming and Montana shows there are no monitors violating the 1997
PM2.5 NAAQS. Between 1999 and 2009, just two monitors in any
of these bordering states violated the 1997 PM2.5 NAAQS.
Both violations were for the annual NAAQS. The first such monitor is in
Libby, Montana, which has not violated the 1997 PM2.5 NAAQS
since 2005. As discussed previously, EPA believes that existing
information supports the conclusion that there is not significant
contribution to nonattainment from Idaho sources to this area in
Montana. The second is a monitor in Salt Lake City, Utah, which
violated the 1997 PM2.5 NAAQS at a single monitor in 2004.
Since 2004 it has not violated the NAAQS. Taking into account the total
weight of all of the factors discussed above, EPA concludes that Idaho
does not significantly contribute to 1997 PM2.5 NAAQS
nonattainment in another state.
2. 1997 Ozone Nonattainment Areas and Monitoring Data in States
Surrounding Idaho
1997 8-Hour Ozone Nonattainment Areas
To address whether Idaho sources significantly contribute to
nonattainment of the 1997 8-hour ozone standard in another state,
Idaho's SIP uses the same approach as it used for the 1997
PM2.5 NAAQS. Relying primarily on TSDs prepared for EPA's 8-
hour ozone and PM2.5 nonattainment designations, Idaho noted
that air stagnation is cited as a major contributing factor to
nonattainment in those areas and that under stagnant air conditions
there is little to no transport of pollutants over long distances.
Idaho also noted that none of the TSDs identified Idaho sources as
significant contributors to any 1997 8-hour ozone nonattainment area.
EPA also reviewed and analyzed information available for the
designated 1997 8-hour ozone nonattainment areas in states surrounding
Idaho. Although significant contribution must be measured not just
against nonattainment areas, but against areas with monitors showing
violations of the NAAQS, nonattainment areas are a convenient starting
point for the analysis. For the 1997 8-hour ozone NAAQS, the only
nonattainment area in states bordering Idaho is Clark County in
southern Nevada (Las Vegas area). In 2005, EPA designated this area
nonattainment for violations of the 1997 8-hour ozone standard. 69 FR
23858 (April 30, 2004) and 40 CFR 81.329. EPA has evaluated whether
emissions from Idaho contribute significantly to the nonattainment of
the 8-hour ozone standard in Clark County. Clark County is about 350
miles south of the closest point on the Idaho border. Distance per se
is not an obstacle to long range
[[Page 55498]]
transport of ozone and/or its precursors, as discussed in the January
30, 2004, notice proposing CAIR (69 FR 4599); NOX (the
primary ozone precursor that was the object of the CAIR transport
study) may be transported for long distances, contributing
significantly to high ozone concentrations in other states. However,
with increasing distance there are greater opportunities for ozone and/
or NOX dispersion and/or removal from the atmosphere due to
the effects of winds and chemical sink processes. In this context, one
may conclude that the 350 mile distance between Idaho and the Clark
County nonattainment area decreases, but does not exclude, the
possibility of significant contribution to this area's nonattainment.
Another transport factor is wind direction. Clark County, Nevada is
south of Idaho and, therefore, is not in the predominant direction of
winds from Idaho. Transport winds across Idaho generally flow from west
to east, and not toward the south. Given the relatively long distance
between Idaho and Clark County, Nevada and the general west-to-east
direction of transport winds across Idaho, EPA believes it is
reasonable to conclude that Idaho sources do not significantly
contribute to nonattainment of the 1997 8-hour ozone NAAQS in Clark
County, Nevada.
Ozone Monitoring Data in Other Areas of Surrounding States
As mentioned above, EPA considers not only significant contribution
to designated nonattainment areas, but also to areas with monitor
readings showing violations of the NAAQS. A review of the most recent
monitoring data from EPA's Air Quality System (AQS) for the bordering
states of Washington, Oregon, Nevada, Utah, Wyoming and Montana shows
no monitors violating for the 1997 8-hour ozone NAAQS. A review of past
monitoring data from 1999 through 2008 shows that the only area in any
of these border states that violated the 1997 8-hour ozone NAAQS was
Salt Lake City, Utah. This area, however, is not currently violating
and has not violated the 1997 8-hour ozone NAAQS since a violation
occurred at a single monitor in 2007. Observed days of high ozone
levels in the Salt Lake City metropolitan area are usually associated
with a `bowl effect' resulting from an inversion that has a stagnant
air pollution mass surrounded by the Oquirrh Mountains to the west, the
Great Salt Lake to the north, and the Wasatch Range on the east.\12\ In
light of these considerations, it is unlikely that Idaho makes a
significant contribution of ozone and/or ozone precursors in the Salt
Lake City area.
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\12\ Approval and Promulgation of State Implementation Plans;
State of Utah; Interstate Transport of Pollution and Other Revisions
(73 FR 16543, March 28, 2008).
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In addition, none of the ozone monitors in Idaho have themselves
indicated a violation of the 1997 8-hour ozone NAAQS, and Boise, Idaho,
the area of Idaho with the highest concentrations of ozone, is almost
300 miles from Salt Lake City. The absence of violations in Idaho
itself do not rule out the possibility of transport, but taken in
conjunction with other relevant information, this fact helps to support
the conclusion that there is no such transport from Idaho to Salt Lake
City. Distance per se is also not an obstacle to long range transport
of ozone and/or its precursors, as discussed above. However, with
increasing distance there are greater opportunities for ozone and/or
NOX dispersion and/or removal from the atmosphere due to the
effects of winds and chemical sink processes. In this context, the 300
mile distance between Idaho and the Salt Lake City area reduces but
does not exclude the possibility of significant contribution to this
area's nonattainment. Taking into account the total weight of all of
the factors discussed above, EPA concludes that Idaho does not
significantly contribute to 1997 8-hour ozone NAAQS nonattainment in
another state.
3. State Regulatory Provisions
In addition to monitoring data providing evidence that Idaho
sources do not contribute to nonattainment in any other state, Idaho
points to air quality provisions in its regulations that prohibit
emissions that contribute significantly to nonattainment. Specifically,
the State points to its air quality provisions at IDAPA 58.01.01.203.02
that require that a proposed source's projected emissions will not
cause or significantly contribute to a violation of any ambient air
quality standard. The state explains that this provision applies to
both major and minor sources and that the owner or operator of such a
source must demonstrate that the source's projected emissions will not
cause or significantly contribute to a violation of any ambient air
quality standard. In addition, they point out that the demonstration is
not constrained to evaluating impacts solely in Idaho and that all
estimates of ambient concentrations must be based on the requirements
specified in 40 CFR 51, Appendix W, which look to the point of maximum
concentration, not a jurisdictional boundary.
The state also relies on its rules for existing sources at IDAPA
58.01.01.401.03, which provide IDEQ with the authority to require a
permit (called a ``Tier II permit'') if emission rate reductions are
necessary to attain any ambient air quality standard. As part of the
Tier II permitting process, the facility operator (or responsible
official) must demonstrate the source does not cause or significantly
contribute to a violation of any ambient air quality standards. The
state asserts that it has used this authority in the past as part of a
suite of control measures implemented to address nonattainment and
other air quality issues and this authority could be used if the
state's emissions were significantly contributing to nonattainment in
another state. For example, between 2000 and 2003 the state issued
fifteen Tier II permits to sources in two PM10 nonattainment
areas to establish federally-enforceable emission limits on
PM10 emissions in order to ensure that the PM10
NAAQS would be attained and maintained. A summary of these 15 permits,
including links to the permits on the Idaho website, is included in the
docket for this rulemaking.
Idaho incorporates by reference annually any updates to the NAAQS
ensuring that implementation of the regulatory provisions at IDAPA
58.01.01.203.02 and IDAPA 58.01.01.40.03 are implementing the most
recently revised NAAQS.
In light of these air quality provisions in Idaho's regulations and
evidence that Idaho has used these air quality provisions to address
nonattainment and other air quality issues in the past, EPA believes
that in this case these regulatory provisions provide additional
support for our conclusion that emissions from Idaho sources do not
significantly contribute to nonattainment in any other state and that
Idaho has the ability to address nonattainment if, in the future, the
state's emissions significantly contribute to nonattainment of the 1997
8-hour ozone and 1997 PM2.5 NAAQS in another state.
4. Conclusion Regarding Significant Contribution to Nonattainment
The data and weight of the evidence analysis presented above
support EPA's conclusion that the Idaho Interstate Transport SIP
(submitted on June 28, 2010) is adequate to ensure that emissions from
Idaho do not significantly contribute to nonattainment in any other
state for the
[[Page 55499]]
1997 8-hour ozone or 1997 PM2.5 NAAQS, consistent with the
requirements of element (1) of CAA section 110(a)(2)(D)(i)
B. EPA's Evaluation of Interference With Maintenance
1. Background
The second element of CAA section 110(a)(2)(D)(i) requires that a
state's SIP must prohibit any source or other type of emissions
activity in the state from emitting pollutants that would ``interfere
with maintenance'' of the applicable NAAQS in any other state. The CAA
does not specifically mandate how interference with maintenance is to
be determined. Therefore, EPA has interpreted this term in past
regulatory actions, such as the 1998 NOX SIP Call, in which
EPA took action to remediate emissions of NOX that
significantly contributed to nonattainment, or interfered with
maintenance of, the then applicable ozone NAAQS through interstate
transport of NOX and the resulting ozone.\13\ The
NOX SIP Call was the mechanism through which EPA evaluated
whether or not the NOX emissions from sources in certain
states had such prohibited interstate impacts, and if they had such
impacts, required the states to adopt substantive SIP revisions to
eliminate the NOX emissions, whether through participation
in a regional cap and trade program or by other means.
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\13\ See, 63 FR 57356 (October 27, 1998). EPA's general approach
to section 110(a)(2)(D) was upheld in Michigan v. EPA, 213 F.3d 663
(D.C. Cir. 2000), cert denied, 532 U.S. 904 (2001). However, EPA's
approach to interference with maintenance in the NOX SIP
Call was not explicitly reviewed by the court. See, North Carolina
v. EPA, 531 F.3d 896, 907-09 (D.C. Cir. 2008).
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After promulgation of the 1997 8-hour ozone NAAQS and the 1997
PM2.5 NAAQS, EPA again recognized that regional transport
was a serious concern throughout the eastern United States and
therefore developed the 2005 CAIR to address emissions of SO2 and
NOX that exacerbate ambient ozone and PM2.5
levels in many downwind areas through interstate transport.\14\ Within
CAIR, EPA likewise interpreted the term ``interfere with maintenance''
as part of the evaluation of whether or not the emissions of sources in
certain states had such impacts on areas that EPA determined would
either be in violation of the NAAQS, or would be in jeopardy of
violating the NAAQS, in a modeled future year unless action were taken
by upwind states to reduce SO2 and NOX emissions. Through
CAIR, EPA again required states that had such interstate impacts to
adopt substantive SIP revisions to eliminate the SO2 and NOX
emissions, whether through participation in a regional cap and trade
program or by other means.
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\14\ See, 70 FR 25162 (May 12, 2005).
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EPA's 2006 Guidance addressed CAA section 110(a)(2)(D) requirements
for the 1997 8-hour ozone NAAQS and 1997 PM2.5 NAAQS. For
those states subject to CAIR, EPA indicated that compliance with CAIR
would meet the two requirements of section 110(a)(2)(D)(i)(I) for these
NAAQS. For states not within the CAIR region, EPA recommended that
states evaluate whether or not emissions from their sources would
``interfere with maintenance'' in other states, following the
conceptual approach adopted by EPA in CAIR. After recommending various
types of information that could be relevant for the technical analysis
to support the SIP submission, such as the amount of emissions and
meteorological conditions in the state, EPA further indicated that it
would be appropriate for the state to assess impacts of its emissions
on other states using considerations comparable to those used by EPA
``in evaluating significant contribution to nonattainment in the
CAIR.''\15\ EPA did not make specific recommendations for how states
should assess ``interfere with maintenance'' separately, and discussed
the first two elements of section 110(a)(2)(D) together without
explicitly differentiating between them.
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\15\ 2006 Guidance at page 5.
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In 2008, however, the U.S. Court of Appeals for the DC Circuit
found that CAIR and the related CAIR federal implementation plan were
unlawful.\16\ Among other issues, the court held that EPA had not
correctly addressed the second element of section 110(a)(2)(D)(i)(I) in
CAIR. The court noted that ``EPA gave no independent significance to
the `interfere with maintenance' prong of section 110(a)(2)(D)(i)(I) to
separately identify upwind sources interfering with downwind
maintenance.'' \17\ EPA's approach, the court reasoned, would leave
areas that are ``barely meeting attainment'' with ``no recourse'' to
address upwind emissions sources.\18\ The court therefore concluded
that a plain language reading of the statute requires EPA to give
independent meaning to the interfere with maintenance requirement of
section 110(a)(2)(D) and that the approach used by EPA in CAIR failed
to do so.
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\16\ See, North Carolina v. EPA, 531 F.3d 896 (D.C. Circuit
2008).
\17\ Id. 531, F.3d at 909.
\18\ Id.
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In addition to affecting CAIR directly, the court's decision in the
North Carolina case indirectly affects EPA's recommendations to states
in the 2006 Guidance with respect to the interfere with maintenance
element of section 110(a)(2)(D) because the agency's guidance suggested
that states use an approach comparable to that used by EPA in CAIR.
States such as Idaho have made SIP submissions that rely upon the
recommendations in EPA's 2006 Guidance. Given the court decision on
CAIR in the interim, however, EPA believes that it is necessary to
evaluate these state submissions for section 110(a)(2)(D) in such a way
as to assure that the interfere with maintenance element of the statute
is given independent meaning and is appropriately evaluated using the
types of information that EPA recommended in the 2006 Guidance. To
accomplish this, EPA believes it may be necessary to supplement the
technical analysis provided the state in order to adequately evaluate
the submissions with the respect to the interfere with maintenance
element of section 110(a)(2)(D).
EPA has recently proposed a new rule to address interstate
transport pursuant to section 110(a)(2)(D), the ``Federal
Implementation Plans to Reduce Interstate Transport of Fine Particulate
Matter and Ozone'' (Transport Rule Proposal), in order to address the
judicial remand of CAIR.\19\ As part of the Transport Rule Proposal,
EPA specifically reexamined the section 110(a)(2)(D) requirement that
emissions from sources in a state must not ``interfere with
maintenance'' of the 1997 8-hour ozone NAAQS and 1997 PM2.5
NAAQS in other states. In the proposal, EPA developed an approach to
identify areas that it predicts to be close to the level of the 1997 8-
hour ozone NAAQS and 1997 PM2.5 NAAQS, and therefore at risk
to become nonattainment for these NAAQS unless emissions from sources
in other states are appropriately controlled. This approach starts by
identifying those specific geographic areas for which further
evaluation is appropriate, and differentiates between areas where the
concern is with interference with maintenance, rather than with
significant contribution to nonattainment.
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\19\ See ``Federal Implementation Plans to Reduce Interstate
Transport of Fine Particulate Matter and Ozone,'' 75 FR 45210
(August 2, 2010).
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As described in more detail below, EPA's analysis evaluates data
from existing monitors over three overlapping three year periods (i.e.,
2003-2005, 2004-2006, and 2005-2007), as well as
[[Page 55500]]
air quality modeling data, in order to determine which areas are
predicted as likely to be violating the 1997 8-hour ozone and
PM2.5 NAAQS in 2012, and which areas are predicted to
potentially have a difficulty with maintaining attainment as of that
date. In essence, if an area's projected data for 2012 indicates that
it would be violating the NAAQS based on the average of these three
overlapping periods, then this monitor location is appropriate for
comparison for purposes of the significant contribution to
nonattainment element of section 110(a)(2)(D). If, however, an area's
projected data indicate that it would be violating the NAAQS based on
the highest single period, but not over the average of the three
periods, then this monitor location is appropriate for comparison for
purposes of the interfere with maintenance element of the statute.\20\
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\20\ A memorandum in the docket for this action provides the
information EPA used in order to identify monitors that are
receptors for evaluation of interference with maintenance for
certain states in the western United States. See, Memorandum from
Brian Timin of EPA's Office of Air Quality Planning and Standards,
Air Quality Modeling Group entitled ``Documentation of Future Year
Ozone and Annual PM2.5 Design Values for Western States'' (August
2010) (Timin Memo).
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By this method, EPA has identified those areas with monitors that
are appropriate ``maintenance sites'' or maintenance ``receptors'' for
evaluating whether the emissions from sources in another state could
interfere with maintenance in that particular area. EPA then uses other
analytical tools to examine the potential impacts of emissions from
upwind states on these maintenance sites in downwind states. EPA
believes that this new approach for identifying those areas that are
predicted to have maintenance problems is appropriate to evaluate the
section 110(a)(2)(D) SIP submission of a state for the interfere with
maintenance element.\21\ EPA's 2006 Guidance did not provide this
specific recommendation to states, but in light of the court's decision
on CAIR, EPA will itself follow this approach in acting upon the Idaho
submission.
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\21\ To begin this analysis, EPA first identifies all monitors
projected to be in nonattainment or, based on historic variability
in air quality, projected to have maintenance problems in 2012. The
``problem'' is that these maintenance areas are at risk not to stay
in attainment because they are so close to the level of the 1997
ozone and PM2.5 NAAQS that minor variations in weather or
emissions could result in violations of the NAAQS in 2012.
---------------------------------------------------------------------------
As explained in the 2006 Guidance, EPA does not believe that
section 110(a)(2)(D) SIP submissions from all states necessarily need
to follow precisely the same analytical approach of CAIR or the
Transport Rule Proposal. In the 2006 Guidance, EPA stated that: ``EPA
believes that the contents of the SIP submission required by section
110(a)(2)(D) may vary, depending upon the facts and circumstances
related to the specific NAAQS. In particular, the data and analytical
tools available at the time the State develops and submits a SIP for a
new or revised NAAQS necessarily affects the contents of the required
submission.'' \22\ EPA also indicated in the 2006 Guidance that it did
not anticipate that sources in states outside the geographic area
covered by CAIR were significantly contributing to nonattainment, or
interfering with maintenance, in other states.\23\ As noted in the
Transport Rule Proposal, EPA continues to believe that the more
widespread and serious transport problems in the eastern United States
are analytically distinct.\24\ For the 1997 8-hour ozone NAAQS and the
1997 PM2.5 NAAQS, EPA believes that nonattainment and
maintenance problems in the western United States are relatively local
in nature with only limited impacts from interstate transport. In the
Transport Rule Proposal, EPA did not calculate interstate ozone or
PM2.5 contributions to or from western states.
---------------------------------------------------------------------------
\22\ 2006 Guidance at 4.
\23\ Id. at 5.
\24\ See, Transport Rule Proposal, 75 FR 45210 (August 2, 2010)
at page 45227.
---------------------------------------------------------------------------
Accordingly, EPA believes that section 110(a)(2)(D) SIP submissions
for states outside the geographic area of the Transport Rule Proposal
may be evaluated using a ``weight of the evidence'' approach that takes
into account available relevant information, such as that recommended
by EPA in the 2006 Guidance for states outside the area affected by
CAIR. Such information may include, but is not limited to, the amount
of emissions in the state relevant to the NAAQS in question, the
meteorological conditions in the area, the distance from the state to
the nearest monitors in other states that are appropriate receptors, or
such other information as may be probative to consider whether sources
in the state may interfere with maintenance of the 1997 8-hour ozone
NAAQS and 1997 PM2.5 NAAQS in other states. These
submissions can rely on modeling when acceptable modeling technical
analyses are available, but EPA does not believe that modeling is
necessarily required if other available information is sufficient to
evaluate the presence or degree of interstate transport in a given
situation.
2. Idaho's Interference With Maintenance Demonstration
To show that Idaho emissions, as controlled under its SIP, do not
interfere with maintenance of the 1997 8-hour ozone NAAQS and 1997
PM2.5 NAAQS in another state, Idaho's submittal analyzed
several types of factors to support its assertion. First, for its
PM2.5 analysis, Idaho relied on information from the Western
Regional Air Partnership (WRAP) Technical Support System (TSS). The
WRAP TSS is a system developed in a collaborative effort by state and
tribal governments and federal agencies to provide the tools needed to
comply with the federal Regional Haze Rule. Idaho used it to provide
general insight on how Idaho sources influence PM2.5
concentrations in Class I areas in surrounding states. For the 8-hour
ozone NAAQS, Idaho evaluated NOX and VOC emissions data from
Idaho sources. These emissions data were evaluated to understand how
Idaho's emissions sources may contribute to ozone impacts in
surrounding states. The WRAP TSS results provided in Idaho's submittal
to address the 1997 PM2.5 standard and Idaho's evaluation of
NOX and VOC emissions data from Idaho sources to address the
1997 8-hour ozone NAAQS are discussed later.
Idaho also relied on information about air stagnation conditions in
other states to show that Idaho sources do not interfere with
maintenance of the 1997 8-hour ozone NAAQS and 1997 PM2.5
NAAQS. Idaho argued that stagnant air conditions are associated with
weak transport and were cited in technical support documents for the 8-
hour ozone and PM2.5 designations as a major contributing
factor to poor air quality in surrounding states. Idaho also identified
its state air quality regulations to demonstrate both that Idaho can,
and does, work with other states and tribes to ensure that an Idaho
activity would not interfere with maintenance by any other State with
respect to the NAAQS.
Idaho also relies on its permitting rules discussed earlier that
not only require for new sources a demonstration that the proposed
source's emissions will not cause or significantly contribute to a
violation of any ambient air quality standard, but also specifically
require for existing sources an operating permit if emission rate
reductions are necessary to attain or maintain any ambient air quality
standard. It also points out that neither of these required
demonstrations is limited to an analysis of impacts solely in Idaho. In
light of these provisions and evidence that Idaho has used these air
quality provisions in the
[[Page 55501]]
past, as discussed in the section on significant contribution (section
IV.A), EPA believes that in this case these regulatory provisions
support our conclusion that Idaho does not interfere with maintenance
in any other state and that Idaho has the ability to address
interference with maintenance if in the future the state's emissions
interfere with maintenance of the 1997 8-hour ozone and 1997
PM2.5 NAAQS in another state.
3. EPA Supplemental Analysis
On July 6, 2010, the EPA proposed a rulemaking proposal (the
Transport Rule Proposal) in response to the judicial remand of CAIR.
The Transport Rule Proposal includes a new approach to determine
whether emissions from a state interfere with maintenance of the 1997
8-hour ozone NAAQS and the 1997 PM2.5 NAAQS in other states.
EPA is using a comparable approach to that of the Transport Rule
Proposal in this action in order to evaluate whether emissions from
Idaho sources interfere with maintenance of these NAAQS in other
states.
In the Transport Rule Proposal, EPA projected future concentrations
of ozone and PM2.5 to identify areas that are expected to be
out of attainment with the NAAQS or to have difficulty maintaining
compliance with the NAAQS in 2012. These areas are referred to as
nonattainment and maintenance receptors, respectively. These
nonattainment and maintenance receptors are based on projections of
future air quality at existing ozone and PM2.5 monitoring
sites in those locations. EPA then used these sites as the receptors
for examining the contributions of emissions from sources located in
upwind states to nonattainment and maintenance problems at these
monitoring locations. Monitoring data was obtained from AQS.
For the PM2.5 NAAQS EPA evaluated concentrations of both
the annual PM2.5 NAAQS and the 24-hour PM2.5
NAAQS. The 1997 annual PM2.5 NAAQS is met when the 3-year
average of the annual mean concentration is 15.0 micrograms per cubic
meter ([mu]g/m\3\) or less. The 3-year average annual mean
concentration is computed at each site by averaging the daily Federal
Reference Method (FRM) samples by quarter, averaging these quarterly
averages to obtain an annual average, and then averaging the three
annual averages to get the design value. The 2006 24-hour
PM2.5 NAAQS is met when the 3-year average of the annual
98th percentile PM2.5 concentrations is 35 [mu]g/m\3\ or
less. The 1997 24-hour PM2.5 NAAQS is met when the 3-year
average of the annual 98th percentiles is 65 [mu]g/m\3\ or less. The 3-
year average mean 98th percentile concentration is computed at each
site by averaging the 3 individual annual 98th percentile values at
each site. The 3-year average 98th percentile concentration is referred
to as the 24-hour average design value. In this action, EPA is only
evaluating whether Idaho's emissions impact other states' ability to
maintain the 1997 annual and 24-hour PM2.5 NAAQS and the
1997 8-hour ozone NAAQS, because those are the NAAQS at issue in this
section 110(a)(2)(D) SIP submission. In later actions, the state and
EPA will evaluate the impacts of interstate transport from emissions
from Idaho sources with respect to other NAAQS.
For the ozone NAAQS, EPA evaluated concentrations relevant to the
1997 8-hour ozone NAAQS. The level of the 1997 8-hour ozone NAAQS is
0.08 parts per million (ppm). The 8-hour ozone standard is met if the
3-year average of the annual 4th highest daily maximum 8-hour ozone
concentration is less than or equal to 0.08 ppm (i.e., less than 0.085
ppm based on the rounding convention in 40 CFR part 50 Appendix I).
This 3-year average is referred to as the ``design value.''
To project future ozone and annual PM2.5 design values,
EPA projected future ozone values based on an average of three design
value periods which include the years 2003-2007 (i.e., design values
for 2003-2005, 2004-2006, and 2005-2007). The average of the three
design values creates a ``5-year weighted average'' value. The 5-year
weighted average values were then projected to the future years that
were analyzed for the Transport Rule Proposal.25 26 EPA used
the 5-year weighted average concentrations to project concentrations
anticipated in 2012 to determine which monitoring sites are expected to
be nonattainment in this future year. EPA also projected 2012 design
values based on each of the three year periods (i.e., 2003-2005, 2004-
2006, and 2005-2007). The highest projection is referred to as the
``maximum design value'' and gives an indication of potential
variability in future projections due to differences in actual
meteorology and emissions from what was modeled.
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\25\ See, the Transport Rule Proposal at 75 FR 45210 (August 2,
2010).
\26\ Additional information concerning these weighted averages
is provided in the docket in the Timin Memo.
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EPA identified those sites that are projected to be attainment
based on the 5-year weighted average design value, but that have a
maximum design value (based on a single three year period) that exceeds
the NAAQS, as maintenance sites because EPA anticipates that there will
be more difficulty in maintaining attainment of the NAAQS at these
locations if there are adverse variations in meteorology or emissions.
These projected maintenance sites are the ones that EPA has used to
determine if emissions from Idaho sources potentially interfere with
maintenance of the 1997 8-hour ozone NAAQS and 1997 annual
PM2.5 NAAQS in other states in this action.
For the annual PM2.5 NAAQS, EPA identified from the
modeling analyses conducted for the Transport Rule Proposal the
following sites as maintenance receptors: A site in Cook County,
Illinois in the Chicago area; a site in Harris County, Texas, in the
Houston/Galveston/Brazoria area. From the modeling analysis conducted
for states not included in the Transport Rule Proposal, EPA identified
only sites in southern California. Based on recent monitoring data
(2007-2009 design values that are under final EPA review), the highest
24-hour PM2.5 design value in the 47 states of the
continental U.S. (not including California) is 50 [mu]g/m\3\, which is
well below the level of the 1997 24-hour PM2.5 NAAQS of 65
[mu]g/m\3\.\27\ Therefore, outside of California, there are no areas
that we would expect to have difficulty in maintaining the 1997 24-hour
PM2.5 NAAQS.
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\27\ Data undergoing review from EPA's Air Quality System which
is EPA's repository of ambient air quality data. (http://www.epa.gov/ttn/airs/airsaqs/).
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From the modeling analyses conducted for the Transport Rule
Proposal, EPA identified a number of maintenance sites or receptors for
the 1997 8-hour ozone NAAQS: Several sites in the Texas area and other
sites in Georgia, Pennsylvania, New York and Connecticut.\28\ For the
modeling analysis conducted for states not included in the Transport
Rule Proposal (i.e. states not included fully in the 12 km Transport
Rule Proposal modeling domain), EPA identified several maintenance
sites in southern and central California using available 36 km
modeling.\29\ The 12 km Transport Rule Proposal modeling domain extends
from Texas northward to North Dakota and eastward from the Rocky
Mountains to
[[Page 55502]]
the east coast and includes 37 states and the District of Columbia.
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\28\ Transport Rule Proposal, 75 FR 45210, (August 2, 2010),
pages 45253-45270, and Timin Memo.
\29\ The Transport Rule Proposal identifies nonattainment and
maintenance receptors in the Eastern U.S. It does not include
modeling results for the West. The Timin Memo documents further
evaluation of the 2012 modeling to identify nonattainment and
maintenance receptors in the West.
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Significantly, for both the 1997 PM2.5 NAAQS and the
1997 8-hour ozone NAAQS, EPA's analysis did not identify any
maintenance receptors in the states that border Idaho (Washington,
Oregon, Nevada, Utah, Wyoming and Montana).
(a) Interfere With Maintenance Evaluation for the PM2.5
NAAQS
For the 1997 PM2.5 NAAQS, the closest maintenance
receptor site identified by the Transport Rule Proposal was in Cook
County, Illinois. Cook County, Illinois is over 1000 miles east of the
closest point on Idaho's border, and on the other side of the Rocky
Mountains. Given the relatively long distance and the intervening
mountainous topography between Idaho and Cook County, EPA believes it
is reasonable to conclude that there is a very low probability that
Idaho sources interfere with maintenance in that area. It is also
reasonable to conclude that Idaho emissions would not have such impacts
at other identified maintenance sites east of Cook County.
In the west, the closest maintenance receptor to Idaho was in
Fresno County, California. Fresno County is located almost 400 miles
southwest of the closest point on the Idaho border and on the other
side of the Sierra Nevada Mountains, which act as a natural barrier to
air movement between Idaho and California. In addition, Fresno County,
located in southern California, is not in the predominant direction of
winds from Idaho. As noted earlier, transport winds across Idaho
generally flow from west to east, and not toward the southwest. Given
the relatively long distance between Idaho and southern California, the
intervening mountainous topography, and the general direction of west-
to-east transport winds across Idaho, EPA concludes that there is no
reasonable basis to conclude that Idaho sources interfere with
maintenance of the 1997 PM2.5 NAAQS in those areas. It is
likewise reasonable to conclude that Idaho emissions would not have
such impacts at other identified maintenance sites in California. Based
on EPA modeling and all of these factors taken together, EPA believes
it is reasonable to conclude that Idaho emissions under the SIP do not
interfere with maintenance of the 1997 PM2.5 NAAQS in any
other state.
This conclusion is consistent with the information and analysis
Idaho provided in its SIP submittal regarding interference with
maintenance of the 1997 PM2.5 NAAQS. With respect to
PM2.5, Idaho used the WRAP TSS tools to provide general
insight on how Idaho sources influence PM2.5 concentrations
in surrounding states and to conclude that Idaho sources did not
interfere with maintenance of the 1997 PM2.5 NAAQS in any
other state. Due to the limitations and purpose of the WRAP TSS, Idaho
only evaluated impacts on Class I areas in surrounding states using
these tools. Because EPA's analysis did not predict any of these Class
I areas to have a difficulty with maintaining attainment of the 1997
PM2.5 NAAQS, any impact Idaho might have on those areas
would not, by definition, interfere with maintenance. Therefore,
further evaluation of Idaho's analysis of PM2.5 impacts on
those areas is unnecessary.
(b) Interfere With Maintenance Evaluation for the 8-Hour Ozone NAAQS
For the 1997 8-hour ozone NAAQS, the closest maintenance receptor
site to the east of Idaho was the Dallas-Ft Worth area in Texas.
Dallas-Ft Worth is located over 1,000 miles southeast of the closest
point on Idaho's border and on the other side of the Rocky Mountains.
Given the relatively long distance and the intervening mountainous
topography between Idaho and Dallas-Ft Worth, it is reasonable to
conclude that Idaho sources do not interfere with maintenance in the
Dallas-Ft Worth area. It is also reasonable to conclude that Idaho
emissions would not have such impacts at other identified maintenance
sites elsewhere further east or south of Dallas-Ft Worth.
In the west, the closest maintenance receptor to Idaho was in
Nevada County, California. Nevada County is almost 300 miles southwest
of the closest point on Idaho's border and located on the other side of
the Sierra Nevada Mountains, which act as a natural barrier to air
movement between Idaho and California. In addition, Nevada County is in
central California and is not in the predominant direction of transport
winds. As noted earlier, transport winds across Idaho generally flow
from west to east. Although westerly winds are not always the case,
meteorological data show that transport winds in Idaho tend to be
southerly or westerly during hot and stagnant weather conditions
conducive to ozone formation in California. Given the relatively long
distance between Idaho and central California, the intervening
mountainous topography, and the general direction of west-to-east
transport winds across Idaho, EPA believes it is reasonable to conclude
that Idaho sources do not interfere with maintenance of the 1997 8-hour
ozone NAAQS in Nevada County, California. It is also reasonable to
conclude that Idaho emissions would not have such impacts at other
identified maintenance receptor sites elsewhere in central or southern
California. Based on all of these factors taken together, EPA believes
it is reasonable to conclude that Idaho emissions do not interfere with
maintenance of the 1997 8-hour ozone NAAQS in any other state.
This conclusion is consistent with the information Idaho provided
in its SIP submittal regarding interference with maintenance of the
1997 8-hour ozone NAAQS. For this element for the 8-hour ozone NAAQS,
Idaho evaluated NOX and VOC emissions data to understand how
Idaho's emissions sources may contribute to ozone impacts in
surrounding states and to conclude that Idaho sources do not interfere
with maintenance of the 1997 8-hour ozone NAAQS in any other states.
Because EPA modeling did not predict any of the areas in states
surrounding Idaho to have difficulty with maintaining attainment of the
8-hour ozone NAAQS, any impact Idaho might have on those areas would
not, by definition, interfere with maintenance. Therefore, further
evaluation of Idaho's analysis of ozone impacts on those areas is
unnecessary.
4. Conclusion Regarding Interference With Maintenance
The data and weight of evidence analysis presented above support
the conclusion that the Idaho Interstate Transport SIP (submitted on
June 28, 2010) is adequate and that emissions from Idaho do not
interfere with maintenance in any other state for the 1997 8-hour ozone
or 1997 PM2.5 NAAQS, consistent with the requirements of
element (2) of CAA section 110(a)(2)(D)(I).
C. EPA's Evaluation of Interference With PSD Measures in Other States
The third element of section 110(a)(2)(D)(i) requires a SIP to
contain adequate provisions prohibiting emissions that interfere with
any other state's required measures to prevent significant
deterioration of its air quality. EPA's 2006 Guidance made
recommendations for SIP submissions to meet this requirement with
respect to both the 1997 8-hour ozone NAAQS and the 1997
PM2.5 NAAQS.
EPA believes that Idaho's submission is consistent with the 2006
Guidance, when considered in conjunction with PSD program revisions
that EPA proposed to approve on March 18, 2010 (75 FR 13058). EPA's
proposed approval of Idaho's SIP for purposes of meeting the
requirements of section 110(a)(2)(D)(i)(II) is contingent upon the
final approval of the PSD program
[[Page 55503]]
revisions in the form specified in EPA's proposed approval, referenced
above. The State's submittal indicates in Section 4, ``Interfere with
Prevention of Significant Deterioration of Air Quality,'' that the
State's SIP provisions include an EPA-approved PSD program. Idaho's
regulations for its PSD program were last approved by EPA and made part
of the SIP on January 16, 2003 (68 FR 2217), 40 CFR 52.670, effective
February 18, 2003. On March 18, 2010, EPA proposed to approve Idaho's
PSD rule revisions incorporating into the State's rules the provisions
of EPA's PSD requirements as of July 1, 2008, including the November
29, 2005, Phase 2 rule for the 1997 8-hour ozone NAAQS (70 FR 71612),
and the May 16, 2008, PM2.5 Implementation Rule (73 FR
28321) for the 1997 PM2.5 NAAQS. We anticipate taking final
action approving Idaho's PSD rule revisions before taking final action
on this interstate transport proposal. Therefore, EPA proposes to
approve this SIP provision as adequate for purposes of section
110(a)(2)(D)(i)(II) if EPA has taken final action to approve the
revisions to Idaho's PSD requirements that are consistent with our
proposed action.
EPA believes that the PSD revision for the 1997 8-hour ozone NAAQS
that makes NOX a precursor for ozone for PSD purposes and
the PSD revision for the 1997 PM2.5 NAAQS that makes
SO2 and NOX precursors for PM2.5 for
PSD purposes, taken together with the revised PSD SIP that EPA proposed
to approve on March 18, 2010, and the Interstate Transport SIP that EPA
is proposing to approve in this action, satisfy the requirements of the
third element of section 110(a)(2)(D)(i) for the 1997 8-hour ozone
NAAQS and the 1997 PM2.5 NAAQS. That is, these provisions
ensure that there will be no interference with any other state's
required PSD measures because Idaho's SIP, as proposed for approval in
this action along with the March 18, 2010 proposed action on the
revised PSD rules, will meet current CAA requirements for PSD.
V. Proposed Action
In light of the data and the weight of the evidence analysis
presented above, EPA is proposing to approve revisions to the Idaho
SIP, submitted on June 28, 2010, which adequately demonstrate that for
the 1997 8-hour ozone and 1997 PM2.5 NAAQS, air pollutant
emissions from sources within Idaho do not (1) significantly contribute
to nonattainment of the NAAQS in any other state, (2) interfere with
maintenance of the NAAQS by any other state, and (3) interfere with any
other state's required measures to prevent significant deterioration of
its air quality, as required by section 110(a)(2)(D)(i).
As noted previously, EPA will address element (4), interference
with any other state's required measures to protect visibility, in a
separate action. EPA will also take action on the portion of Idaho's
SIP that addresses the 2006 PM2.5 NAAQS in a separate
action.
VI. Statutory and Executive Order Reviews
Under the Clean Air Act, the Administrator is required to approve a
SIP submission that complies with the provisions of the Act and
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a).
Thus, in reviewing SIP submissions, EPA's role is to approve state
choices, provided that they meet the criteria of the Clean Air Act.
Accordingly, this action merely proposes to approve state law as
meeting Federal requirements and does not impose additional
requirements beyond those imposed by state law. For that reason, this
action:
Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Order
12866 (58 FR 51735, October 4, 1993);
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act; and
Does not provide EPA with the discretionary authority to
address, as appropriate, disproportionate human health or environmental
effects, using practicable and legally permissible methods, under
Executive Order 12898 (59 FR 7629, February 16, 1994).
In addition, this proposed rule does not have tribal implications
as specified by Executive Order 13175 (65 FR 67249, November 9, 2000),
because the SIP is not approved to apply in Indian country located in
the state, and EPA notes that it will not impose substantial direct
costs on tribal governments or preempt tribal law.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Ozone, Particulate matter,
Reporting and recordkeeping requirements, Volatile organic compounds.
Dated: September 2, 2010.
Dennis J. McLerran,
Regional Administrator, Region 10.
[FR Doc. 2010-22773 Filed 9-10-10; 8:45 am]
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