Document ID: EPA-R09-OAR-2010-0585-0001
Agency: epa
Document Type: Proposed Rule
Title: Approval and Promulgation of Implementation Plans and Designation of Areas for Air Quality Planning Purposes: Nevada; Redesignation of Las Vegas Valley to Attainment for the Carbon Monoxide Standard
Posted Date: 2010-07-29T04:00Z

[Federal Register: July 29, 2010 (Volume 75, Number 145)]
[Proposed Rules]               
[Page 44734-44753]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr29jy10-11]                         

-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2010-0585; FRL-9182-7]

 
Approval and Promulgation of Implementation Plans and Designation 
of Areas for Air Quality Planning Purposes; State of Nevada; 
Redesignation of Las Vegas Valley to Attainment for the Carbon Monoxide 
Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

-----------------------------------------------------------------------

SUMMARY: EPA is proposing to approve the State of Nevada's request to 
redesignate to attainment the Las Vegas Valley nonattainment area for 
the carbon monoxide national ambient air quality standard. EPA is also 
proposing to approve the carbon monoxide maintenance plan and motor 
vehicle emissions budgets for the area, as well as certain additional 
revisions to the Nevada State implementation plan. These revisions 
include the suspension of a local wintertime cleaner burning gasoline 
rule, and the relaxation of a State rule governing wintertime gasoline 
in Clark County. EPA's proposed approval is contingent upon receipt of 
a supplemental submittal from the State of Nevada containing a 
commitment to reinstate the existing vapor pressure limit in the State 
wintertime gasoline rule, if necessary, and thereby to implement the 
related contingency measure in the maintenance plan.

DATES: Comments must be received on or before August 30, 2010.

ADDRESSES: Submit comments, identified by docket number EPA-R09-OAR-
2010-0585, by one of the following methods:
    1. Federal eRulemaking Portal: http://www.regulations.gov. Follow 
the on-line instructions for submitting comments.
    2. E-mail: oconnor.karina@epa.gov.
    3. Mail or deliver: Karina O'Connor (AIR-2), U.S. Environmental 
Protection Agency Region IX, 75 Hawthorne Street, San Francisco, CA 
94105-3901.
    Instructions: Direct your comments to Docket ID No. EPA-R09-OAR-
2010-0585. 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 e-mail. The http://www.regulations.gov Web site 
is an ``anonymous access'' system, which means that EPA will not know 
your identity or contact information unless you provide it in the body 
of your comment. If you send e-mail directly to EPA, without going 
through http://www.regulations.gov, your e-mail 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

[[Page 44735]]

submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of the 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 docket are listed in the http://
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other information, 
such as copyrighted material, 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 at the 
Office of Air Planning, Environmental Protection Agency (EPA), Region 
IX, 75 Hawthorne Street, San Francisco, California. To inspect the hard 
copy materials, please schedule an appointment during normal business 
hours with the contact listed in the FOR FURTHER INFORMATION CONTACT 
section.

FOR FURTHER INFORMATION CONTACT: Karina O'Connor, EPA Region IX, (775) 
833-1276, oconnor.karina@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, the terms ``we,'' 
``us,'' and ``our'' refer to EPA. This supplementary information is 
organized as follows:

Table of Contents

I. Summary of Today's Proposed Action
II. Background
III. Procedural Requirements for Adoption and Submittal of SIP 
Revisions
IV. Substantive Requirements for Redesignation
V. Evaluation of the State's Redesignation Request for Las Vegas 
Valley
    A. Determination That the Area Has Attained the Applicable NAAQS
    B. The Area Must Have a Fully Approved SIP Meeting Requirements 
Applicable for Purposes of Redesignation Under Section 110 and Part 
D
    1. Basic SIP Requirements Under CAA Section 110
    2. Part D Requirements
    a. Introduction
    b. RFP and Attainment Demonstration
    c. Reasonable Available Control Measures/Control Technology
    d. Emission Inventory
    e. Permits for New and Modified Major Stationary Sources
    f. Contingency Provisions
    g. Conformity Requirements
    h. VMT Forecasts and Annual Updates
    i. Vehicle Inspection and Maintenance Program
    j. TCMs To Offset VMT-Related Emissions Increases and To Provide 
for RFP
    k. Oxygenated Gasoline Program
    l. Clean Data Policy and CO Milestone Requirement
    3. Conclusion With Respect to Section 110 and Part D 
Requirements
    C. The Area Must Show the Improvement in Air Quality Is Due to 
Permanent and Enforceable Emissions Reductions
    D. The Area Must Have a Fully Approved Maintenance Plan Under 
CAA Section 175A
    1. Attainment Inventory
    2. Maintenance Demonstration
    3. Monitoring Network
    4. Verification of Continued Attainment
    5. Contingency Provisions
    6. Subsequent Maintenance Plan Revisions
    7. Motor Vehicle Emissions Budgets
    8. Conclusion
VI. Evaluation of Suspended or Relaxed Wintertime Gasoline 
Specifications
VII. Proposed Action and Request for Comment
VIII. Statutory and Executive Order Reviews

I. Summary of Today's Proposed Action

    EPA is proposing to approve the Nevada Division of Environmental 
Protection's (NDEP's) request to redesignate to attainment the Las 
Vegas Valley \1\ carbon monoxide (CO) nonattainment area located within 
Clark County, Nevada, and related revisions to the Nevada State 
implementation plan (SIP). The specific SIP revision submittals that we 
are proposing to approve are listed in the following table:
---------------------------------------------------------------------------

    \1\ Specifically, the Las Vegas Valley CO nonattainment area is 
defined by reference to State hydrographic area 212. See 40 
CFR 81.329. The Las Vegas Valley encompasses roughly 1,500 square 
miles within Clark County and includes the cities of Las Vegas, 
North Las Vegas, and Henderson. Roughly two million people reside in 
Clark County, mostly within Las Vegas Valley. NDEP is the State 
agency under State law that is responsible for SIP matters for the 
State of Nevada. Within Clark County, the Clark County Board of 
Commissioners, acting through the Department of Air Quality and 
Environmental Management (DAQEM), is empowered under State law to 
develop air quality plans and to regulate stationary sources within 
the county with the exception of certain types of power plants, 
which lie exclusively within the jurisdiction of NDEP.

------------------------------------------------------------------------
                                                       State of Nevada
        Plan or Rule            Adoption date(s)      submittal date(s)
------------------------------------------------------------------------
Carbon Monoxide               Adopted by the Clark  Submitted by NDEP by
 Redesignation Request and     County Board of       letter dated
 Maintenance Plan, Las Vegas   Commissioners on      September 18, 2008.
 Valley Nonattainment Area,    September 2, 2008.
 Clark County, Nevada
 (September 2008).
Clark County Air Quality      Adopted by the Clark  Submitted by NDEP by
 Regulations, Section 54       County Board of       letter dated March
 (``Cleaner Burning Gasoline   Commissioners on      26, 2010.
 (CBG): Wintertime             September 15, 2009,
 Program'') (Suspended).       effective September
                               29, 2010.
Nevada Administrative Code    Adopted by the        Submitted by NDEP by
 (NAC) section 590.065         Nevada Board of       letter dated March
 (amended).                    Agriculture on        26, 2010.
                               December 9, 2010,
                               effective January
                               28, 2010.
------------------------------------------------------------------------

    Specifically, we are proposing to approve NDEP's maintenance plan 
submittal dated September 18, 2008 titled Carbon Monoxide Redesignation 
Request and Maintenance Plan, Las Vegas Valley Nonattainment Area, 
Clark County, Nevada (September 2008) (``Las Vegas Valley CO 
Maintenance Plan'' or ``Maintenance Plan'') \2\ as a revision to the 
Nevada SIP, and to approve NDEP's request to redesignate Las Vegas 
Valley to attainment for the CO NAAQS. We are proposing to approve the 
Las Vegas Valley CO Maintenance Plan because we find that it meets all 
requirements for such plans in section 175A under the Clean Air Act 
(``Act'' or CAA), and we are proposing to approve NDEP's redesignation 
request for Las Vegas Valley from nonattainment to attainment because 
we believe that the area has met all of the criteria for redesignation 
under CAA section 107(d)(3)(E). The Las Vegas Valley CO Maintenance 
Plan includes CO motor vehicle emissions budgets (MVEBs) for years 
2008, 2010, and 2020,

[[Page 44736]]

and we are proposing to approve these budgets for the purposes of 
transportation conformity based on our conclusion that they meet the 
criteria for such budgets in 40 CFR 93.118(e). Final approval of the 
redesignation request and maintenance plan would change the legal 
description of the Las Vegas Valley CO nonattainment area in 40 CFR 
part 81 from nonattainment to attainment, and would make Federally 
enforceable the commitments and contingency provisions contained in the 
maintenance plan.
---------------------------------------------------------------------------

    \2\ The Las Vegas Valley CO Maintenance Plan consists of the 
main body of the plan and three appendices: Appendix A (``Wintertime 
Gasoline Fuel Specification Study''), Appendix B (Technical Support 
Document, Carbon Monoxide Modeling for the Clark County Maintenance 
Plan''), Appendix C (``Documentation of the Public Review 
Process'').
---------------------------------------------------------------------------

    In connection with the CO Maintenance Plan, Clark County and the 
State of Nevada have decided to suspend or relax two gasoline-related 
regulations that formed part of the control strategy that has provided 
for attainment of the CO standard in Las Vegas Valley but that they 
believe are not needed for the purposes of maintaining the CO standard 
now that the CO standard has been attained. These are Clark County Air 
Quality Regulations (AQR) Section 54 (``Cleaner Burning Gasoline: 
Wintertime Program'') (herein, referred to as the ``CBG Rule''), which 
establishes certain wintertime gasoline specifications related to 
sulfur and aromatic hydrocarbons (``aromatics''), and Nevada 
Administrative Code (NAC) section 590.065 (herein referred to as the 
``Low RVP Rule''), which establishes a low Reid vapor pressure (RVP) 
specification for gasoline sold during the late fall and winter months 
in Clark County. We are proposing to approve the suspension of Clark 
County's CBG Rule and the relaxation of the State's Low RVP Rule 
because we conclude, in accordance with CAA section 110(l), that doing 
so would not interfere with attainment or maintenance of any of the 
NAAQS or any applicable requirement of the Clean Air Act.\3\
---------------------------------------------------------------------------

    \3\ We are not including subsection (7) of amended NAC 590.065 
in our proposed approval because the limits in subsection (7) of the 
amended rule are unrelated to the vapor pressure requirement and 
associated CO emissions reductions, and are severable from the rest 
of the rule.
---------------------------------------------------------------------------

    The Las Vegas Valley CO Maintenance Plan includes reinstatement of 
the CBG Rule and the Low RVP Rule as contingency measures, as required 
under CAA section 175A(d). However, while Clark County, through 
adoption of the maintenance plan, has committed to reinstatement of the 
CBG Rule in accordance with the contingency provisions of the plan, the 
Nevada State Department of Agriculture, which is responsible for the 
Low RVP Rule, has not yet made a similar commitment with respect to the 
Low RVP Rule. Thus, our approval of the Maintenance Plan and 
redesignation request is contingent upon the submittal, and EPA 
approval, of such a commitment as a revision to the Nevada SIP.\4\
---------------------------------------------------------------------------

    \4\ On July 12, 2010, the Nevada Department of Agriculture 
initiated a 30-day comment period to solicit comment (or request a 
public hearing) on the draft commitment regarding implementation of 
the contingency measure in the Maintenance Plan related to 
reinstatement of the Low RVP Rule. The Department's notice of intent 
to solicit public comment, which includes the commitment language, 
has been placed in the docket for this rulemaking. We have reviewed 
the language of the Department's draft commitment and expect to 
approve it if it is ultimately submitted to us without significant 
modification.
---------------------------------------------------------------------------

II. Background

    Carbon monoxide (CO) is a colorless, odorless gas emitted in 
combustion processes. In most areas where elevated CO levels are found, 
CO comes primarily from tailpipe emissions of cars and trucks. Exposure 
to elevated CO levels is associated with impairment of visual 
perception, work capacity, manual dexterity and learning ability, and 
with illness and death for those who already suffer from cardiovascular 
disease, particularly angina or peripheral vascular disease.
    On April 30, 1971 (see 36 FR 8186), pursuant to section 109 of the 
Act, as amended in 1970, EPA promulgated the original national ambient 
air quality standards (NAAQS) for several pervasive air pollutants, 
including CO. NAAQS represent concentration levels the attainment and 
maintenance of which, allowing for an adequate margin of safety, EPA 
has determined to be requisite to protect public health (``primary'' 
NAAQS) and welfare (``secondary'' NAAQS). The primary (i.e., health-
based) NAAQS for CO is 9 parts per million (ppm) averaged over an 8-
hour period, and 35 ppm averaged over 1 hour, neither to be exceeded 
more than once per year. In our 1971 rulemaking, we established 
identical primary and secondary NAAQS for CO but later revoked the 
secondary (welfare) NAAQS for CO. See 50 FR 37484 (September 13, 1985). 
The (primary) CO NAAQS established by EPA in 1971, remain in effect 
today. See 40 CFR 50.8 (``National primary ambient air quality 
standards for carbon monoxide'').
    Under section 110 of the Act, each State is required to adopt and 
submit to EPA a plan that provides for the implementation, maintenance, 
and enforcement of the NAAQS within each State. These plans are 
referred to as ``State implementation plans'' or ``SIPs.'' Under the 
Clean Air Act, as amended in 1970, SIPs were required to provide for 
attainment of the NAAQS within 3 years after EPA approval of the plan. 
However, many areas of the country did not attain the NAAQS within the 
statutory period.
    In response, Congress amended the Act in 1977 to establish a new 
approach, based on area designations, for attaining the NAAQS, and on 
March 3, 1978 (43 FR 8962), we promulgated attainment status 
designations for all areas within each of the States. In the 1978 
rulemaking, we designated Las Vegas Valley as a ``nonattainment'' area 
for the CO NAAQS based on monitored violations of the 8-hour CO 
NAAQS.\5\ See 43 FR 8962, at 9013 (March 3, 1978).
---------------------------------------------------------------------------

    \5\ Thus, the CO plans previously approved by EPA for Las Vegas 
Valley assume that the 8-hour CO standard, rather than the 1-hour CO 
standard, is the controlling standard. That is, attainment of the 
former necessarily means attainment of the latter. The same holds 
true in the submitted Las Vegas Valley CO Maintenance Plan, which 
includes a maintenance demonstration for the 8-hour CO standard, not 
the 1-hour CO standard.
---------------------------------------------------------------------------

    The Clean Air Act, as amended in 1977, required States to revise 
their SIPs by preparing, adopting and submitting attainment plans (for 
EPA approval) that set forth a strategy to achieve the NAAQS in 
designated nonattainment areas. The original statutory deadline for 
attainment under the 1977 Amended Act was 1982, but extensions to 1987 
were allowed if certain SIP requirements were met. In response, Clark 
County and the State of Nevada adopted and implemented various air 
quality plans and programs, including a vehicle inspection and 
maintenance (I/M) program, to reduce CO levels in Las Vegas Valley. EPA 
approved these plans and programs at various times as revisions to the 
Nevada State implementation plan (SIP). See 46 FR 21758 (April 14, 
1981); 47 FR 15790 (April 13, 1982); 49 FR 44208 (November 5, 1984). 
Despite these programs, Las Vegas Valley did not attain the CO NAAQS by 
the then-applicable 1987 attainment date.
    The CAA was significantly amended by Congress in 1990 to establish 
new attainment dates and planning and control requirements for areas, 
like Las Vegas Valley, that had failed to attain the NAAQS under the 
1977 Amendments. Under the 1990 Amended Act, Las Vegas Valley was 
initially classified as a ``moderate'' nonattainment area for CO (based 
on a design value of 14.4 ppm) but was subsequently reclassified as a 
``serious'' CO nonattainment area after having failed to attain the 
standard by the applicable attainment date (i.e., December 31, 1995) 
for moderate areas.

[[Page 44737]]

See 62 FR 51604 (October 2, 1997). The Las Vegas Valley area was then 
subject to the applicable attainment deadline for ``serious'' CO 
nonattainment areas (i.e., December 31, 2000). See CAA section 
186(a)(1).
    In response to nonattainment classifications and related CAA 
requirements, Clark County and the State of Nevada adopted and 
implemented new air quality plans and programs, including a ``serious'' 
area attainment plan titled Carbon Monoxide State Implementation Plan, 
Las Vegas Valley Nonattainment Area, Clark County, Nevada (August 2000) 
(``2000 Las Vegas Valley CO Plan'' or ``2000 CO Plan''). We approved 
the 2000 Las Vegas Valley CO Plan in 2004. See 69 FR 56351 (September 
21, 2004).
    In connection with the 2000 Las Vegas Valley CO Plan, we approved, 
among other plan elements, Clark County AQR Section 54 (``Cleaner 
Burning Gasoline (CBG): Wintertime Program'') (i.e., the CBG Rule) 
(originally adopted by Clark County in 1999), the State's alternate 
``low'' enhanced vehicle I/M program for Las Vegas Valley and Boulder 
City, the State's regulation establishing a low RVP wintertime gasoline 
specification for Clark County (i.e., the Low RVP Rule) (originally 
adopted by the State Board of Agriculture in 1995), the State's 
alternative fuels for government fleets program, the Regional 
Transportation Commission of Southern Nevada's (RTC's) Transportation 
Control Measures/Transportation Demand Management (TCM/TDM) program, 
and an amended version of previously approved Clark County AQR Section 
53 (``Oxygenated Gasoline Program'') (originally adopted by Clark 
County in 1991). The 2000 Las Vegas Valley CO Plan identifies the CBG 
Rule, I/M program, Low RVP Rule, and the oxygenated gasoline program, 
along with the Federal Motor Vehicle Control Program (FMVCP), as the 
primary control measures providing for attainment of the CO NAAQS in 
Las Vegas Valley by the applicable attainment date (2000). In 2004, we 
also approved the 2000 CO Plan's motor vehicle emissions budgets 
(MVEBs) for years 2000, 2010 and 2020.\6\
---------------------------------------------------------------------------

    \6\ While important for the purposes of attaining the CO 
standard by the applicable attainment date (2000), the Maintenance 
Plan shows that the Low RVP Rule and the CBG Rule are no longer 
necessary for the purposes of maintaining the CO standard. The 
consistent, but more gradual, emissions reduction benefits of the 
FMVCP and natural vehicle turnover (i.e., replacement of older more 
polluting motor vehicles with newer cleaner vehicles) allow for the 
relaxation of these fuel rules consistent with continued maintenance 
of the CO standard.
---------------------------------------------------------------------------

    In 2005, EPA determined that the Las Vegas Valley had attained the 
CO NAAQS by its applicable attainment deadline of December 31, 2000 [70 
FR 31353 (June 1, 2005)], and had continued to attain through 2003 [70 
FR 3174, at 3177 (January 21, 2005)]. This attainment determination did 
not constitute redesignation to attainment, however, because it did not 
include consideration or approval of the additional requirements for 
redesignation set forth in CAA section 107(d)(3)(E), e.g., a 
maintenance plan satisfying CAA section 175A.
    In 2006, EPA approved a Las Vegas Valley CO plan titled Carbon 
Monoxide State Implementation Plan Revision, Las Vegas Valley 
Nonattainment Area, Clark County, Nevada (October 2005) (``2005 Las 
Vegas Valley CO Plan'' or ``2005 CO Plan''), which amended the 
emissions inventories, attainment demonstration, and related MVEBs from 
the 2000 Las Vegas Valley CO Plan in response to changes in the EPA-
approved motor vehicle emission factor model and higher-than-forecast 
increases in population growth in Las Vegas Valley. See 71 FR 44587 
(August 7, 2006).
    EPA today is proposing to approve the State's request to 
redesignate the Las Vegas Valley to attainment for the CO NAAQS, and to 
approve the Las Vegas Valley CO Maintenance Plan. We are also proposing 
approval of the suspension or relaxation of two specific control 
measures that had previously been approved into the SIP, but that Clark 
County has shown are no longer needed to maintain the CO NAAQS in Las 
Vegas Valley: the County's CBG Rule and the State's Low RVP Rule. Our 
evaluation of the submittals and the redesignation request is provided 
in the following sections of this document.

III. Procedural Requirements for Adoption and Submittal of SIP 
Revisions

    Section 110(l) of the Act requires States to provide reasonable 
notice and public hearing prior to adoption of SIP revisions. In this 
action, we are proposing action on the following SIP revisions: The Las 
Vegas Valley CO Maintenance Plan, submitted by NDEP on September 18, 
2008; and the suspended or relaxed wintertime gasoline regulations, 
submitted by NDEP on March 26, 2010.
    Both of the SIP revision submittals cited above contain evidence 
that reasonable notice of a public hearing was provided to the public 
and that a public hearing was conducted prior to adoption. 
Specifically, notice of the availability of, and opening of a 30-day 
comment period on, the draft CO maintenance plan was published on 
several dates in a newspaper of general circulation within the Las 
Vegas area beginning on May 11, 2008. The Clark County Board of 
Commissioners adopted the Las Vegas Valley CO Maintenance Plan by 
resolution on September 2, 2008 at the close of the public hearing. 
Appendix C to the plan documents the public review process used by the 
county to adopt the plan. Following adoption, Clark County DAQEM 
forwarded the plan to NDEP, the Governor of Nevada's designee for SIP 
matters, and NDEP then submitted the plan as a revision to the Nevada 
SIP to EPA for approval.
    NDEP's March 26, 2010 SIP submittal documents the public review 
process used by the Clark County Board of Commissioners in suspending 
Section 54 (i.e., the CBG Rule) and by the State Board of Agriculture 
in relaxing the wintertime gasoline vapor pressure requirement. 
Specifically, NDEP's March 26, 2010 submittal documents the Clark 
County Board of Commissioners' September 15, 2009 public hearing on, 
and subsequent adoption of, Ordinance No. 3809 suspending the CBG Rule, 
effective September 29, 2009. Notice of Clark County DAQEM's workshop 
to discuss suspension of the CBG Rule was published on several dates in 
a newspaper of general circulation within the Las Vegas area beginning 
on May 17, 2009.
    The March 26, 2010 SIP revision submittal also documents the State 
Board of Agriculture's December 9, 2009 public hearing on, and 
subsequent adoption of, amendments to NAC section 590.065 (LCB File No. 
R111-08), effective January 28, 2010, including the relaxation of the 
RVP wintertime gasoline limit in Clark County from 9.0 to 13.5 pounds 
per square inch (psi). This action on the part of the Board of 
Agriculture was preceded by publication on September 16, 2009 by the 
Nevada Department of Agriculture of a notice of a workshop to be held 
on October 13, 2009 to solicit comments on amendments to NAC section 
590.065, and by publication on November 4, 2009 of a notice of intent 
to act upon a regulation.
    Based on the documentation submitted with the two SIP submittals 
and summarized above, we find that both SIP revisions cited above 
satisfy the procedural requirements of section 110(l) of the Act for 
revising SIPs.

[[Page 44738]]

IV. Substantive Requirements for Redesignation

    The CAA establishes the requirements for redesignation of a 
nonattainment area to attainment. Specifically, section 107(d)(3)(E) 
allows for redesignation provided that the following criteria are met: 
(1) EPA determines that the area has attained the applicable NAAQS; (2) 
EPA has fully approved the applicable implementation plan for the area 
under section 110(k); (3) EPA determines that the improvement in air 
quality is due to permanent and enforceable reductions in emissions 
resulting from implementation of the applicable SIP, applicable Federal 
air pollution control regulations, and other permanent and enforceable 
reductions; (4) EPA has fully approved a maintenance plan for the area 
as meeting the requirements of CAA section 175A; and (5) the State 
containing such area has met all requirements applicable to the area 
under section 110 and part D of the CAA. Section 110 identifies a 
comprehensive list of elements that SIPs must include, including plan 
revisions meeting the requirements of part D (i.e., CAA section 171 
through section 193), and part D establishes the SIP requirements for 
nonattainment areas. Part D is divided into six subparts; the CO-
specific nonattainment SIP requirements are found in part D, subpart 3, 
which includes CAA sections 186 and 187.
    EPA provided guidance on redesignations in a document entitled, 
``State Implementation Plans; General Preamble for the Implementation 
of Title I of the Clean Air Act Amendments of 1990,'' published in the 
Federal Register on April 16, 1992 (57 FR 13498), and supplemented on 
April 28, 1992 (57 FR 18070) (referred to herein as the ``General 
Preamble''). Another relevant EPA guidance document includes 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' Memorandum from John Calcagni, Director, Air Quality 
Management Division, EPA Office of Air Quality Planning and Standards, 
September 4, 1992 (referred to herein as the ``Calcagni memo'').
    For the reasons set forth below in section V of this document, we 
propose to approve NDEP's request for redesignation of the Las Vegas 
Valley nonattainment area to attainment for the CO NAAQS based on our 
conclusion that all of the criteria under CAA section 107(d)(3)(E) have 
been satisfied. For the reasons set forth in section V.D.5 of this 
document, our proposed approval is contingent upon NDEP's submission of 
a commitment by the Nevada Department of Agriculture to reinstate the 
Low RVP Rule if necessary to address future violations of the CO NAAQS 
in Las Vegas Valley and thereby implement the related contingency 
measure in the Maintenance Plan.

V. Evaluation of the State's Redesignation Request for Las Vegas Valley

A. Determination That the Area Has Attained the Applicable NAAQS

    CAA section 107(d)(3)(E) requires that we determine that the area 
has attained the NAAQS. EPA makes the determination as to whether an 
area's air quality is meeting the CO NAAQS based upon air quality data 
gathered at CO monitoring sites in the nonattainment area which have 
been entered into the Air Quality System (AQS) database. This data is 
reviewed to determine the area's air quality status in accordance with 
40 CFR 50.8; EPA policy guidance as stated in a memorandum from William 
G. Laxton, Director Technical Support Division, entitled ``Ozone and 
Carbon Monoxide Design Value Calculations,'' dated June 18, 1990; and 
EPA's General Preamble at 57 FR 13535.
    The 8-hour and 1-hour CO design values are used to determine 
attainment of CO areas, and the design values are determined by 
reviewing 8 quarters of data, or a total of two complete calendar years 
of data for an area. The 8-hour design value is computed by first 
finding the maximum and second maximum (non-overlapping) 8-hour values 
at each monitoring site for each year of the two calendar years prior 
to and including the attainment date. Then the higher of the ``second 
high'' values is used as the design value for the monitoring site, and 
the highest design value among the various CO monitoring sites 
represents the CO design value for the area.
    The CO NAAQS requires that not more than one 8-hour average per 
year equals or exceeds 9.5 ppm (values below 9.5 are rounded down to 9 
and are not considered exceedances). If an area has a design value that 
is equal to or greater than 9.5 ppm, this means that there was a 
monitoring site where the second highest (non-overlapping) 8-hour 
average was measured to be equal to or greater than 9.5 ppm in at least 
one of the two years being reviewed to determine attainment for the 
area. This indicates that there were at least two values above the 
NAAQS during one year at that site and thus the NAAQS for CO was not 
met. Conversely, an 8-hour design value of less than 9.5 ppm indicates 
that the area has attained the CO NAAQS. The 1-hour CO design value is 
computed in the same manner. An area attains the one-hour CO NAAQS if 
the 1-hour design value is less than 35.5 ppm.
    On June 1, 2005 (70 FR 31353), we determined that the Las Vegas 
Valley ``serious'' CO nonattainment area had attained the CO NAAQS by 
the applicable attainment date (2000) based on complete quality-assured 
data showing a design value of the area (from Sunrise Acres station) 
for 1999-2000 of 8.2 ppm, eight-hour average, and 10.2 ppm, one-hour 
average. (The corresponding NAAQS are 9 ppm, eight-hour average, and 35 
ppm, one-hour average.) We also found that Las Vegas Valley had 
continued to attain the standard through year 2003. As part of that 
determination, we reviewed the ambient CO monitoring network operated 
by Clark County DAQEM and found that it met or exceeded our 
requirements. See 70 FR 3174 (January 21, 2005).
    In our proposed determination that the area had attained by its 
attainment deadline (2000) (70 FR 3174, January 21, 2005), we described 
Clark County's CO monitoring network at that time as including 7 SLAMS 
sites, 4 NAMS sites, and 4 special purpose sites.\7\ Since our 2005 
finding of attainment, Clark County has closed a number of CO 
monitoring sites. There are now five CO monitoring sites in Las Vegas 
Valley: Winterwood, East Sahara, Sunrise Acres, Orr School and J.D. 
Smith. All of the monitoring sites are SLAMS, and the J.D. Smith site 
is also a NAMS site. All sites have population exposure as their 
monitoring objective except Sunrise Acres, which has ``highest 
concentration'' as its monitoring objective.
---------------------------------------------------------------------------

    \7\ EPA has established ambient air quality monitoring 
requirements and standards for State and Local Air Monitoring 
Stations (SLAMS) and for National Air Monitoring Stations (NAMS). 
These requirements and standards provide for operating schedules, 
data quality assurance, and for the design and siting of CO 
samplers.
---------------------------------------------------------------------------

    While the number of CO monitoring stations has been reduced, we 
conclude in our Technical Systems Audit Report (February 2010) that the 
network currently meets or exceeds the requirements for the minimum 
number of CO monitoring sites. Moreover, we note that the Sunrise Acres 
monitoring station, which is the site at which the highest CO 
concentrations have historically been recorded, remains among those 
that continue to be operated by Clark County DAQEM.
    For the purposes of this proposed rule, we reviewed complete, 
quality-assured monitoring data that are

[[Page 44739]]

uploaded to our Air Quality System (AQS) database. We found that no 
exceedances of the CO NAAQS were recorded in Las Vegas Valley during 
the entire period from 2004-2009. During this period, the highest 8-
hour CO concentrations were 60% of the NAAQS or less at all of the 
monitoring stations. Table 1 summarizes the 2nd highest 8-hour and 1-
hour average CO concentrations at the various monitoring stations 
during the most recent two-year period. As shown in the table, the 8-
hour design value for the area based on 2008-2009 data is 3.7 ppm, 
eight-hour average, and 4.7 ppm, 1-hour average, both of which are well 
below the corresponding NAAQS of 9 and 35 ppm, respectively. 
Preliminary data available for 2010 show that there continue to be no 
exceedances of the CO NAAQS in the area.

                                           Table 1--Summary of Las Vegas Valley CO Monitoring Data, 2008-2009
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              2nd highest 8-hour concentration (ppm)          2nd highest 1-hour concentration (ppm)
                  Monitoring site name                   -----------------------------------------------------------------------------------------------
                                                               2008            2009        Design value        2008            2009        Design value
--------------------------------------------------------------------------------------------------------------------------------------------------------
Winterwood..............................................             2.9             2.8             2.9             3.8             3.7             3.8
East Sahara.............................................             3.7             3.1             3.7             4.7             4.2             4.7
Sunrise Acres...........................................             3.5             2.8             3.5             4.2             4.7             4.7
Orr School..............................................             2.6             2.6             2.6             3.2             3.2             3.2
J.D. Smith..............................................             2.5             2.4             2.5             3.6             3.2             3.6
                                                         -----------------------------------------------------------------------------------------------
Area Design Value.......................................  8-Hour CO Design Value = 3.7 ppm (East Sahara)
                                                          1-Hour CO Design Value = 4.7 ppm (East Sahara
                                                          and Sunrise Acres)
                                                         -----------------------------------------------------------------------------------------------
CO NAAQS................................................  9 ppm
                                                          35 ppm
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on the AQS data presented above and the positive assessment 
of the Clark County DAQEM ambient CO monitoring network that we made in 
February 2010, we propose to determine that Las Vegas Valley has 
attained the CO NAAQS, and thus meets the criterion for redesignation 
set forth in section 107(d)(3)(E)(i).

B. The Area Must Have a Fully Approved SIP Meeting Requirements 
Applicable for Purposes of Redesignation Under Section 110 and Part D

    Section 107(d)(3)(E)(ii) and (v) require EPA to determine that the 
area has a fully approved applicable SIP under section 110(k) that 
meets all applicable requirements under section 110 and part D for the 
purposes of redesignation.
1. Basic SIP Requirements Under CAA Section 110
    Section 110(a)(2) sets forth the general elements that a SIP must 
contain in order to be fully approved. Although section 110(a)(2) was 
amended in 1990, a number of the requirements did not change in 
substance, and therefore, EPA believes that the pre-amendment EPA-
approved SIP met these requirements in Las Vegas Valley with respect to 
CO. As to those requirements that were amended, (see 57 FR 27936 and 
27939, June 23, 1992), many are duplicative of other requirements of 
the Act. EPA has analyzed the Nevada SIP and determined that it is 
consistent with the requirements of amended section 110(a)(2). The Las 
Vegas Valley portion of the approved Nevada SIP contains enforceable 
emission limitations; requires monitoring, compiling and analyzing of 
ambient air quality data; requires preconstruction review of new or 
modified stationary sources; provides for adequate funding, staff, and 
associated resources necessary to implement its requirements; and 
provides the necessary assurances that the State maintains 
responsibility for ensuring that the CAA requirements are satisfied in 
the event that Clark County is unable to meet its CAA obligations.\8\
---------------------------------------------------------------------------

    \8\ The applicable SIP for NDEP and Clark County may be found at 
http://yosemite.epa.gov/r9/r9sips.nsf/allsips?readform&state=Nevada.
    We note that SIPs must be fully approved only with respect to 
applicable requirements for purposes of redesignation in accordance 
with section 107(d)(3)(E)(ii). Thus, for example, CAA section 
110(a)(2)(D) requires that SIPs contain certain measures to prevent 
sources in a State from significantly contributing to air quality 
problems in another State. However, the section 110(a)(2)(D) 
requirements for a State are not linked with a particular 
nonattainment area's designation and classification in that State. 
EPA believes that the requirements linked with a particular 
nonattainment area's designation and classification are the relevant 
measures to evaluate in reviewing a redesignation request. The 
transport SIP submittal requirements, where applicable, continue to 
apply to a State regardless of the designation of any one particular 
area in the State.
    Thus, we do not believe that these requirements should be 
construed to be applicable requirements for purposes of 
redesignation. In addition, EPA believes that the other section 110 
elements not connected with nonattainment plan submissions and not 
linked with an area's attainment status are not applicable 
requirements for purposes of redesignation. The State will still be 
subject to these requirements after Las Vegas Valley is 
redesignated. The section 110 and part D requirements, which are 
linked with a particular area's designation and classification, are 
the relevant measures to evaluate in reviewing a redesignation 
request. This policy is consistent with EPA's existing policy on 
applicability of conformity (i.e., for redesignations) and 
oxygenated fuels requirement. See Reading, Pennsylvania, proposed 
and final rulemakings 61 FR 53174-53176 (October 10, 1996), 62 FR 
24816 (May 7, 1997); Cleveland-Akron-Lorain, Ohio, final rulemaking 
61 FR 20458 (May 7, 1996); and Tampa, Florida, final rulemaking 60 
FR 62748 (December 7, 1995). See also the discussion of this issue 
in the Cincinnati redesignation 65 FR 37890 (June 19, 2000), in the 
Pittsburgh redesignation 66 FR 50399 (October 19, 2001), and in the 
Los Angeles redesignation 72 FR 6986 (February 14, 2007) and 72 FR 
26718 (May 11, 2007). EPA believes that section 110 elements not 
linked to the area's nonattainment status are not applicable for 
purposes of redesignation.
---------------------------------------------------------------------------

    On numerous occasions over the past 38 years, NDEP has submitted 
and we have approved provisions addressing the basic CAA section 110 
provisions. There are no outstanding or disapproved applicable SIP 
submittals with respect to the Las Vegas Valley portion of the SIP. We 
propose to conclude that NDEP and Clark County have met all SIP 
requirements for Las Vegas Valley applicable for purposes of 
redesignation under section 110 of the CAA (General SIP Requirements). 
With the exception discussed below in Section V.B.2.l of this document, 
the SIP for Las Vegas Valley also has been approved as meeting 
applicable requirements under part D of Title I of the CAA.
2. Part D Requirements
a. Introduction
    The requirements that apply under part D (of Title I) of the Act to 
``serious'' CO nonattainment areas are set forth in sections 172, 176, 
187, and 211. In the General Preamble, we have issued guidance 
describing how we will review SIPs and SIP revisions submitted under 
part D (of Title I) of the Act, including

[[Page 44740]]

those containing ``serious'' CO nonattainment area SIP provisions. In 
the following paragraphs, we explain how the State has met the 
applicable SIP revision requirements under part D for the Las Vegas 
Valley CO nonattainment area or where, in the case of certain 
requirements, how the requirement does not apply because Las Vegas 
Valley has attained the CO standard.\9\
---------------------------------------------------------------------------

    \9\ In addition, we note that the State has not sought to 
exercise the options available under CAA sections 172(c)(4) 
(identification and quantification of certain emissions increases) 
and 172(c)(8) (equivalent techniques). Thus, these provisions are 
not relevant to the request for redesignation for the Las Vegas 
Valley CO nonattainment area.
---------------------------------------------------------------------------

b. RFP and Attainment Demonstration
    Under CAA sections 172(c)(2) and 187(a)(7), with respect to a 
serious CO nonattainment area, States are required to a submit a SIP 
revision that provides, and a demonstration that the plan as revised 
will provide, for attainment of the CO NAAQS by the applicable 
attainment date and provisions for such specific annual emission 
reductions as are necessary to attain the standard by that date. In 
2004, in approving the 2000 Las Vegas Valley CO Plan, we approved the 
area's RFP demonstration under sections 172(c)(2) and 187(a)(7) and 
attainment demonstration under section 187(a)(7). See 69 FR 56351, at 
56353 (September 21, 2004). Thus, the area has met the SIP requirements 
under CAA sections 172(c)(2) and 187(a)(7).
c. Reasonable Available Control Measures/Control Technology
    Section 172(c)(1) of the Act requires States to submit a SIP 
revision for nonattainment areas that provide for the implementation of 
all reasonably available control measures (RACM) as expeditiously as 
practicable (including such reductions in emissions from existing 
sources in the area as may be obtained through the adoption, at a 
minimum, of reasonably available control technology (RACT)) and shall 
provide for attainment of the NAAQS. RACM is a more general term that 
can refer to stationary, area or mobile sources while RACT is a term 
that refers to stationary sources.
    Attainment of the CO NAAQS in Las Vegas Valley relied upon the 
Federal Motor Vehicle Control Program and five State or local control 
measures: The State's vehicle I/M program, the State's Low RVP Rule, 
Clark County's rules (AQR sections 53 (i.e., wintertime oxygenated 
gasoline rule) and the CBG Rule) establishing wintertime gasoline 
requirements related to oxygen content, sulfur content, and aromatics, 
and to a lesser degree, the State's Alternative Fuels for Government 
Fleets program, and RTC's TCM/TDM program. We have previously approved 
all of these State and local control measures into the Nevada SIP. 
Based on our 2005 determination that Las Vegas Valley had attained the 
CO NAAQS by the applicable attainment date (2000), we believe that no 
additional measures need be submitted to fulfill the RACM/RACT 
requirement of CAA section 172(c)(1) in the Las Vegas Valley CO 
nonattainment area.
d. Emissions Inventory
    Sections 172(c)(3) and 187(a)(1) of the Act require States to 
submit a comprehensive, accurate, current inventory of actual CO 
emissions for year 1990 from all sources within the nonattainment area. 
The inventory is to address actual CO emissions during the peak CO 
season for the area, and all stationary (generally referring to larger 
stationary source or ``point'' sources), area (generally referring to 
smaller stationary and fugitive (non-smokestack) sources), and mobile 
(on-road, nonroad, locomotive and aircraft) sources are to be included 
in the inventory. Section 187(a)(5) requires States to submit periodic 
(every three years) updates to the inventories required under section 
187(a)(1).
    We interpret the Act such that the emission inventory requirements 
of section 172(a)(3), 187(a)(1), and 187(a)(5) are satisfied by the 
inventory requirements of the maintenance plan. See 57 FR 13498, at 
13564 (April 16, 1992). Thus, our proposed approval of the Las Vegas 
Valley CO Maintenance Plan and related CO emission inventories 
satisfies the requirements of sections 172(a)(3), 187(a)(1), and 
187(a)(5) for the purposes of redesignation of Las Vegas Valley to 
attainment for the CO NAAQS. See section V.D herein for details 
concerning the CO emission inventories in the Maintenance Plan.
e. Permits for New and Modified Major Stationary Sources
    Under section 172(c)(5), the CAA requires States to submit SIP 
revisions that establish certain requirements for new or modified 
stationary sources in nonattainment areas, including provisions to 
ensure that major new sources or major modifications of existing 
sources of nonattainment pollutants incorporate the highest level of 
control, referred to as the Lowest Achievable Emission Rate (LAER), and 
that increases in emissions from such stationary sources are offset so 
as to provide for reasonable further progress towards attainment in the 
nonattainment area. The process for reviewing permit applications and 
issuing permits for new or modified stationary sources of air pollution 
is referred to as ``New Source Review'' (NSR). With respect to 
nonattainment pollutants in nonattainment areas, this process is 
referred to as ``nonattainment NSR.''
    In 2004 (69 FR 54006, September 7, 2004), we approved Clark 
County's NSR rules as meeting the requirements of section 172(c)(5). 
See our proposed rule at 69 FR 31056, at 31059 (June 2, 2004) for 
details concerning how Clark County's NSR rules comply with CAA 
requirements for CO nonattainment areas. We have also made a finding 
under section 187(c)(1) that stationary sources do not contribute 
significantly to ambient CO levels in the Las Vegas Valley CO 
nonattainment area. See at 69 FR 56351, at 56353 (September 21, 2004).
    For certain types of power plants in Clark County, NDEP rather than 
Clark County has the authority to issue air pollution permits under 
State law. In 2004, we approved a State rule (NAC section 445B.22083) 
that prohibits new power plants or major modification to existing power 
plants under State jurisdiction within the Las Vegas Valley 
nonattainment area. See 69 FR 31056, 31059 (June 2, 2004) and 69 FR 
54006, at 54017 (September 7, 2004). In 2008, we approved an amended 
version of NAC section 445B.22083. See 73 FR 20536 (April 16, 2008).
    Based on our previous approvals of Clark County's NSR rules and NAC 
section 445B.22083, we find that the State has met the requirements of 
CAA section 172(c)(5).
f. Contingency Provisions
    Sections 172(c)(9) and 187(a)(3) of the Act require a State to 
submit contingency measures that will be implemented if an area fails 
to make reasonable further progress (RFP), if VMT estimates in the 
attainment plan are exceeded, or if the area fails to attain by the 
applicable attainment date. In 2005, based on our determination that 
Las Vegas Valley had attained the CO NAAQS by the applicable attainment 
date, we found that the CAA's requirement for the SIP to provide for CO 
contingency provisions under CAA sections 172(c)(9) and 187(a)(3) no 
longer applies to Las Vegas Valley. See 70 FR 31353 (June 1, 2005).
g. Conformity Requirements
    Under section 176(c) of the Clean Air Act Amendments of 1990, 
States were required to establish criteria and

[[Page 44741]]

procedures to ensure that Federally supported or funded projects 
conform to the air quality planning goals in the applicable SIP. 
Section 176(c) further provided that State conformity provisions must 
be consistent with Federal conformity regulations that the CAA required 
EPA to promulgate. EPA's conformity regulations are codified at 40 CFR 
part 93, subparts A (referred to herein as ``transportation 
conformity'') and B (referred to herein as ``general conformity''). 
Transportation conformity applies to transportation plans, programs, 
and projects developed, funded, and approved under title 23 U.S.C. or 
the Federal Transit Act, and general conformity applies to all other 
Federally-supported or funded projects. SIP revisions intended to 
address the conformity requirements are referred to herein as 
``conformity SIPs.''
    In November 2008, EPA approved Clark County's transportation 
conformity criteria and procedures as meeting the related SIP 
requirements under part 51, subpart T (``Conformity to State or Federal 
Implementation Plans of Transportation Plans, Programs, and Project 
Developed, Funded or Approved Under Title 23 U.S.C. or the Federal 
Transit Laws''). See 73 FR 66182 (November 7, 2008).
    In August 2005, Congress passed the Safe, Accountable, Flexible, 
Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), 
which eliminated the requirement for States to adopt and submit 
conformity SIPs addressing general conformity requirements. See 75 FR 
17254 (April 5, 2010) for conforming changes to EPA's general 
conformity regulations. Based on our approval of Clark County's 
transportation conformity SIP and SAFETEA-LU's elimination of the 
general conformity SIP requirement, we find that Clark County and the 
State have met the requirements for conformity SIPs in Las Vegas Valley 
under CAA section 176(c). In any event, EPA believes it is reasonable 
to interpret the conformity requirements as not applicable for purposes 
of evaluating a redesignation request under section 107(d)(3)(E). See 
Wall v. EPA, 265 F.3d 426, 439 (6th Cir. 2001) upholding this 
interpretation.
h. VMT Forecasts and Annual Updates
    Under CAA section 187(a)(2)(A), States are required to submit a SIP 
revision for serious CO nonattainment areas that contains a forecast of 
VMT in the nonattainment area concerned for each year before the year 
in which the plan projects the CO standard will be attained, and must 
provide for annual updates of the VMT forecasts. In 2004, we approved 
VMT forecasts and the responsible agencies' commitments to revise and 
replace the VMT projections as needed and to monitor actual VMT levels 
in the future, under section 187(a)(2)(A) of the Act (see RTC's 
Resolution No. 149, approved into the SIP in 2004). Thus, we find that 
the SIP requirement for VMT forecasts and annual updates for Las Vegas 
Valley under CAA section 187(a)(2)(A) has been met.
i. Vehicle Inspection and Maintenance Program
    Under section 187(a)(6), the CAA requires States with serious CO 
nonattainment areas to submit a SIP revision that provides for a 
vehicle I/M program that meets applicable Federal I/M requirements, 
including the ``enhanced'' I/M performance standard. In 2004, we 
approved the ``alternate low'' enhanced vehicle I/M program for Las 
Vegas Valley and Boulder City as meeting the requirements of CAA 
section 187(a)(6) and EPA's I/M Regulation (40 CFR part 52, subpart S 
(``Inspection/Maintenance Program Requirements''). See at 69 FR 56351, 
at 56353 (September 21, 2004). Since then, we have approved an update 
to the statutory and regulatory elements of the vehicle I/M program. 
See 73 FR 38124, at 38127 (footnote 31), and 74 FR 3975 (January 22, 
2009). Thus, the vehicle I/M SIP requirement for Las Vegas Valley under 
CAA section 187(a)(6) has been met.
j. TCMs To Offset VMT-Related Emissions Increases and To Provide for 
RFP
    Section 187(b)(2) of the Clean Air Act applies the requirements of 
section 182(d)(1) to serious CO nonattainment areas with the purpose of 
reducing CO emissions rather than emissions of volatile organic 
compounds (VOC). Specifically, section 187(b)(2) requires States with a 
serious CO nonattainment area to submit a SIP revision that identifies 
and adopts specific enforceable transportation control strategies and 
transportation control measures (collectively, ``TCMs'') to offset any 
growth in CO emissions from growth in VMT or numbers of vehicle trips 
in such area and to reduce motor vehicle CO emissions as necessary, in 
combination with other emission reductions requirements, to provide for 
RFP. As noted above, we approved the CO RFP demonstration for Las Vegas 
Valley as part of our approval of the Las Vegas Valley 2000 CO Plan.
    EPA has concluded that States are not required to submit such 
measures if the SIP includes a demonstration that, despite growth in 
projected VMT, CO emissions will decline each year through the 
attainment year. See, e.g., EPA proposed approval of California's 
redesignation request for the South Coast Air Basin at 72 FR 6986 
(February 14, 2007); finalized at 72 FR 26718 (May 11, 2007). In the 
General Preamble, we state that: ``If projected total motor vehicle 
emissions during the ozone season in one year are not higher than 
during the ozone season the year before, given the control measures in 
the SIP, the VMT offset requirement is satisfied.'' General Preamble at 
57 FR 13522. For CO areas, the General Preamble principle quoted above 
applies to motor vehicle emissions of CO during the CO season.
    The Las Vegas Valley 2000 CO Plan includes CO emissions inventories 
for a base year (1996) and the attainment year (2000) that show a sharp 
decline in CO motor vehicle emissions during the 1996 through 2000 
period. See page 6-3 of the Las Vegas Valley 2000 CO Plan. We approved 
the emissions inventories in 2004 (69 FR 56351, September 21, 2004). 
Thus, no TCMs for Las Vegas Valley were required to prevent an increase 
in emissions associated with a growth in VMT or vehicle trips, since 
emissions decline each year through the attainment year despite 
increases in VMT and vehicle trips. Nonetheless, the State did submit a 
TCM/TDM program (RTC's CAT MATCH commuter incentive program) as part of 
the Las Vegas Valley 2000 CO Plan. See 2000 CO Plan, appendix D, 
sections 2 and 9. In 2004, we approved the TCM/TDM program under 
section 187(b)(2) and our voluntary mobile source emissions reduction 
program policy. See 69 FR 56351, at 56353 (September 21, 2004).
    Based on our 2004 approval of the emissions inventories and RFP 
demonstration from the Las Vegas Valley 2000 CO Plan that show that no 
additional TCMs are required to offset VMT-related emissions increases 
or to provide RFP, we find that the TCM-related requirements of CAA 
section 187(b)(2) for Las Vegas Valley have been met.
k. Oxygenated Gasoline Program
    Under sections 187(b)(3) and 211(m), the CAA requires States with 
serious CO nonattainment areas to submit a SIP revision that provides 
for an oxygenated gasoline program. Such a program must require 
gasoline to be blended to contain not less than 2.7% oxygen by weight 
during the period of the year during which CO levels are elevated 
(i.e., the winter months). In 1999, we approved Clark County's 
oxygenated gasoline rule, Section 53 (``Oxygenated

[[Page 44742]]

Gasoline Program'') as meeting the requirements under sections 
187(b)(3) and 211(m). See 64 FR 29573 (June 2, 1999). Clark County AQR 
Section 53 requires gasoline sold in Las Vegas Valley, Eldorado Valley, 
Ivanpah Valley, and the Boulder City limits to be blended to contain 
3.5% oxygen by weight each year from October 1st through March 31st. In 
2004, we approved administrative changes to the rule. See 69 FR 56351, 
at 56353 (September 21, 2004). Thus, the oxygenated gasoline 
requirement under CAA sections 187(b)(3) and 211(m) has been met.
l. Clean Data Policy and CO Milestone Requirement
    CAA section 187(d) (``CO Milestone'') applies to serious CO areas 
and requires: (1) The State to submit a demonstration that the area has 
achieved certain specific annual emission reductions; (2) EPA to 
determine whether the demonstration is adequate; and (3) the State to 
submit a plan revision, if EPA notifies the State that the CO milestone 
demonstration is inadequate, that implements CAA section 182(g)(4) 
economic incentive and transportation control programs sufficient to 
achieve the specific annual emission reductions by the attainment date. 
EPA has not approved a CO Milestone demonstration for Las Vegas Valley, 
but, as explained below, the CO Milestone requirement is linked to the 
RFP requirement in section 187(a)(7), and because RFP has no meaning 
when the area has attained the standard, the CO Milestone requirement 
similarly is no longer meaningful and no corresponding SIP revision is 
required to be approved for purposes of redesignation.
    In some designated nonattainment areas, monitored data demonstrates 
that the NAAQS have already been achieved. Based on its interpretation 
of the Act, EPA has determined that certain SIP submission requirements 
of part D, subparts 1, 2, and 4 of the Act do not apply for purposes of 
evaluating redesignation requests and therefore we do not require 
certain submissions for an area that has attained the NAAQS. These 
include RFP requirements, attainment demonstrations and contingency 
measures, because these provisions have the purpose of helping achieve 
attainment of the NAAQS.
    The Clean Data Policy is the subject of two EPA memoranda setting 
forth our interpretation of the provisions of the Act as they apply to 
areas that have attained the relevant NAAQS. EPA also finalized the 
statutory interpretation set forth in the policy in a final rule, 40 
CFR 51.918, as part of its Final Rule to Implement the 8-hour Ozone 
National Ambient Air Quality Standard--Phase 2 (Phase 2 Final Rule). 
See discussion in the preamble to the rule at 70 FR 71645-71646 
(November 29, 2005). We have also applied the same approach to the 
interpretation of the provisions of subparts 1 and 4 applicable to 
particulate matter with an aerodynamic diameter less than or equal to a 
nominal 10 micrometers (PM-10). For detailed discussions of this 
interpretation with respect to the CAA's PM-10 requirements for RFP, 
attainment demonstrations, and contingency measures, see 71 FR 6352, 
6354 (February 8, 2006); 71 FR 13021, 13024 (March 14, 2006); 71 FR 
27440, 27443-27444 (May 11, 2006); 71 FR 40952, 40954 (July 19, 2006); 
and 71 FR 63642 (October 30, 2006).
    EPA believes that the legal bases set forth in detail in our Phase 
2 Final rule, our May 10, 1995 memorandum from John S. Seitz, entitled 
``Reasonable Further Progress, Attainment Demonstration, and Related 
Requirements for Ozone Nonattainment Areas Meeting the Ozone National 
Ambient Air Quality Standard'' (Seitz memo), and our December 14, 2004 
memorandum from Stephen D. Page entitled ``Clean Data Policy for the 
Fine Particle National Ambient Air Quality Standards'' (Page memo), are 
equally pertinent to the interpretation of provisions of subparts 1 and 
3 applicable to CO. EPA's interpretation of how the provisions of the 
Act apply to areas with ``clean data'' is not logically limited to 
ozone, particulate matter with an aerodynamic diameter less than or 
equal to a nominal 2.5 micrometers (``fine particles'' or PM-2.5), and 
PM-10, because the rationale is not dependent upon the type of 
pollutant. Our interpretation that an area that is attaining the 
standard is relieved of obligations to demonstrate RFP and to provide 
an attainment demonstration and contingency measures pursuant to part D 
of the CAA, pertains whether the standard is CO, 1-hour ozone, 8-hour 
ozone, PM-2.5, or PM-10.
    The reasons for relieving an area that has attained the relevant 
standard of certain part D, subpart 1 and 2 (sections 171 and 172) 
obligations, applies equally as well to part D, subpart 3, which 
contains specific attainment demonstration and RFP provisions for CO 
nonattainment areas. As we have explained in the 8-hour ozone Phase 2 
Final Rule, our ozone and PM-2.5 clean data memoranda, and our approval 
of PM-10 SIPs, EPA believes it is reasonable to interpret provisions 
regarding RFP and attainment demonstrations, along with related 
requirements, so as not to require SIP submissions if an area subject 
to those requirements is already attaining the NAAQS (i.e., attainment 
of the NAAQS is demonstrated with three consecutive years of complete, 
quality-assured air quality monitoring data for ozone and PM, and two 
consecutive years for CO). A number of U.S. Circuit Courts of Appeals 
have upheld EPA rulemakings applying its interpretation of subparts 1 
and 2 with respect to ozone. Latino Issues Forum v. EPA, Nos. 06-75831 
and 08-71239 (9th Cir. March 2, 2009) (memorandum opinion); Sierra Club 
v. EPA, 99 F.3d 1551 (10th Cir. 1996); Sierra Club v. EPA, 375 F.3d 537 
(7th Cir. 2004); Our Children's Earth Foundation v. EPA, No. 04-73032 
(9th Cir. June 28, 2005) (memorandum opinion). It has been EPA's 
longstanding interpretation that the general provisions of part D, 
subpart 1 of the Act (sections 171 and 172) do not require the 
submission of SIP revisions concerning RFP for areas already attaining 
the ozone NAAQS. In the General Preamble, we stated:

[R]equirements for RFP will not apply in evaluating a request for 
redesignation to attainment, since, at a minimum, the air quality 
data for the area must show that the area has already attained. A 
showing that the State will make RFP towards attainment will, 
therefore, have no meaning at that point. 57 FR at 13564.

See also page 6 of the Calcagni memo. EPA believes the same reasoning 
applies to the CO RFP provisions of part D, subpart 3.
    With respect to RFP, CAA section 171(1) states that, for purposes 
of part D of title I, RFP:

means such annual incremental reductions in emissions of the 
relevant air pollutant as are required by this part or may 
reasonably be required by the Administrator for the purpose of 
ensuring attainment of the applicable NAAQS by the applicable date.

The stated purpose of RFP is to ensure attainment by the applicable 
attainment date, whether dealing with the general RFP requirement of 
section 172(c)(2), the ozone-specific RFP requirements of sections 
182(b) and (c), the PM-10 specific RFP requirements of section 
189(c)(1), or the CO-specific RFP requirements of section 187(a)(7).
    Section 187(a)(7) states that the SIP for moderate CO areas with a 
design value greater than 12.7 ppm must:

provide a demonstration that the plan as revised will provide for 
attainment of the carbon monoxide NAAQS by the applicable attainment 
date and provisions for such specific annual emission reductions as 
are necessary to attain the standard by that date.

[[Page 44743]]

This same requirement also applies to serious CO areas in accordance 
with CAA section 187(b)(1).
    It is clear that once the area has attained the standard, no 
further specific annual emission reductions are necessary or 
meaningful. With respect to CO areas, this interpretation is supported 
by language in section 187(d)(3), which mandates that a State that 
fails to achieve the milestone must submit a plan that assures that the 
State achieves the ``specific annual reductions in carbon monoxide 
emissions set forth in the plan by the attainment date.'' Section 
187(d)(3) assumes that the requirement to submit and achieve the 
milestone does not continue after attainment of the NAAQS.
    If an area has in fact attained the standard, the stated purpose of 
the RFP and specific annual emissions reductions requirements will have 
already been fulfilled.\10\ The specific annual emission reductions 
required are only those necessary to attain the standard by the 
attainment date. EPA took this position with respect to the general RFP 
requirement of section 172(c)(2) in the April 16, 1992 General Preamble 
and also in the May 10, 1995 memorandum with respect to the 
requirements of sections 182(b) and (c). We are proposing to extend 
that interpretation to the specific provisions of part D, subpart 3.
---------------------------------------------------------------------------

    \10\ For PM-10 areas, we have concluded that it is a distinction 
without a difference that section 189(c)(1) speaks of the PM-10 
nonattainment area RFP requirement as one to be achieved until an 
area is ``redesignated as attainment'', as opposed to section 
172(c)(2), which is silent on the period to which the requirement 
pertains, or the ozone and CO nonattainment area RFP requirements in 
sections 182(b)(1) or 182(c)(2) for ozone and 187(a)(7) for CO, 
which refer to the RFP requirements as applying until the 
``attainment date'', since, section 189(c)(1) defines RFP by 
reference to section 171(l) of the Act. Reference to section 171(l) 
clarifies that, as with the general RFP requirements in section 
172(c)(2) and the ozone-specific requirements of section 182(b)(1) 
and 182(c)(2) and the CO-specific requirements of section 187(a)(7), 
the PM-specific requirements may only be required for the purpose of 
ensuring attainment of the applicable national ambient air quality 
standard by the applicable date. 42 U.S.C. section 7501(1). As 
discussed in the text of this rulemaking, EPA interprets the RFP 
requirements, in light of the definition of RFP in section 171(l), 
to be a requirement that no longer applies once the standard has 
been attained.
---------------------------------------------------------------------------

    As noted above, CAA section 187(d), CO Milestone, applies to 
serious CO areas and requires the State to submit a demonstration that 
the area has achieved certain specific annual emission reductions. EPA 
interprets this provision consistent with its interpretation of section 
182(g) in subpart 2. See May 10, 1995 Seitz Memorandum at page 5. 
There, EPA included in its identification of SIP submission 
requirements linked with attainment and RFP requirements the ``Section 
182(g) requirements concerning milestones that are based on the section 
182(b)(1) and 182(c)(2)(B) and (C) submissions.'' In Subpart 3, 
similarly, milestone requirements are based on the section 187(a)(7) 
specific annual emission reduction requirements.
    Thus, while Las Vegas Valley does not have an approved SIP with 
respect to the CO Milestone demonstration, we believe that, for the 
reasons set forth here and established in our prior ``clean data'' 
memoranda and rulemakings, a CO nonattainment area that has ``clean 
data'' should be relieved of the part D, subpart 3 obligation to 
provide the CAA section 187(d) CO milestone demonstration. Based on our 
2005 determination that Las Vegas Valley attained the CO NAAQS by the 
applicable attainment date, and the above detailed rationale, we 
conclude that the requirement for a CO milestone demonstration under 
section 187(d) no longer applies to Las Vegas Valley.
3. Conclusion With Respect to Section 110 and Part D Requirements
    Based on our evaluation of the various SIP requirements and 
submittals discussed above, we propose to find that the State has a 
fully approved SIP for section 110 and part D requirements applicable 
for purposes of redesignation of Las Vegas Valley for the CO NAAQS, and 
that the criteria for redesignation in section 107(d)(3)(E)(ii) and (v) 
are met.

C. The Area Must Show the Improvement in Air Quality Is Due to 
Permanent and Enforceable Emissions Reductions

    Section 107(d)(3)(E)(iii) precludes redesignation of a 
nonattainment area to attainment unless EPA determines that the 
improvement in air quality is due to permanent and enforceable 
reductions in emissions resulting from implementation of the applicable 
SIP and applicable Federal air pollution control regulations and other 
permanent and enforceable regulations. If EPA makes such a 
determination, then the criterion is satisfied.
    The 2000 and 2005 Las Vegas Valley CO plans credit the following 
control measures in demonstrating attainment of the CO NAAQS in Las 
Vegas Valley: the Federal Motor Vehicle Control Program; the State's 
vehicle I/M program; the State's Low RVP Rule (NAC section 590.065); 
Clark County's wintertime gasoline requirements, including Clark County 
AQR Section 53 (``Oxygenated Gasoline Program'') and the CBG Rule; and 
to a lesser extent, the State's Alternative Fuels for Government Fleets 
Program and RTC's voluntary TCM/TDM program. All of the State and local 
control measures listed above have been approved into the SIP and are 
thus Federally enforceable.
    The Federal Motor Vehicle Control Program has contributed to 
improved air quality through the gradual, continued turnover and 
replacement of older vehicle models with newer models manufactured to 
meet increasingly stringent Federal tailpipe emissions standards. The 
emissions reductions from the Federal Motor Vehicle Control Program are 
reflected in the emissions inventories and maintenance demonstration 
discussed later in this document through the use of EPA's MOBILE 
emission factor model for on-road motor vehicles. The State and local 
control measures further reduce CO emissions from on-road motor 
vehicles, the single largest source category in the CO emissions 
inventory for Las Vegas Valley.
    A rough sense of the effectiveness of the control measures to 
reduce CO emissions can be gained by a comparison between area-wide CO 
emissions in 1996 (a nonattainment year) with those in 2006 (an 
attainment year). In 1996, area-wide CO emissions in Las Vegas Valley 
were estimated to be approximately 662 tons per day (average winter 
weekday), and in 2006, despite an increase in population and VMT of 
approximately 90% and 70%, respectively, area-wide CO emissions dropped 
approximately 10% (to 581 tons per day average winter weekday).\11\
---------------------------------------------------------------------------

    \11\ See tables 3-2 and 3-12 from the 2005 CO Plan for estimates 
of population, VMT, and area-wide CO emissions.
---------------------------------------------------------------------------

    With respect to permanence and enforceability, none of the State or 
local control measures relied upon for attainment have sunset clauses, 
and all would continue to be implemented under the Las Vegas Valley CO 
Maintenance Plan, with the exception of the State's Low RVP Rule, and 
the County's CBG Rule.\12\ For the reasons set forth in section VI of 
this document, we are proposing to approve the suspension or relaxation 
of these two control measures because, among other reasons, the 
maintenance demonstration in the Las Vegas Valley CO Maintenance

[[Page 44744]]

Plan shows that they are not necessary to maintain the CO standard, at 
least through 2020. Moreover, as required under CAA section 175A(d), 
Clark County has committed to reinstating the CBG Rule as a contingency 
measure if needed to address any violations of the CO standard that 
might occur after redesignation to attainment. The Nevada Department of 
Agriculture has not yet made the commitment to seek reinstatement of 
the Low RVP Rule, and thus our proposed approval of the relaxation of 
the Low RVP Rule is contingent upon submittal of the necessary 
commitment. The commitments to reinstatement of the wintertime gasoline 
requirements by Clark County and the Nevada Department of Agriculture, 
once approved, will become Federally enforceable under the CAA.
---------------------------------------------------------------------------

    \12\ The CO Maintenance Plan also lists the State's Alternative 
Fuels for Government Fleets Program and RTC's TCM/TDM program as 
contingency measures, meaning that the plan takes no credit for the 
measures in its maintenance demonstration. However, the State has 
not requested rescission, suspension, or relaxation of these two 
control measures and thus they will remain Federally enforceable 
control measures under the CAA until EPA approves such a request as 
a revision to the Nevada SIP.
---------------------------------------------------------------------------

    With respect to the connection between the emissions reductions and 
the improvement in air quality, the Las Vegas Valley CO Maintenance 
Plan provides a demonstration that the air quality improvement in Las 
Vegas Valley, that resulted in attainment of the CO NAAQS by 2000 and 
continued attainment since then, is due to emission reductions from 
implementation of the control measures discussed above and is not the 
result of a local economic downturn or unusual or extreme weather 
patterns. The demonstration shows that from 1990 to 2007, despite 
increases in population, employment growth, increases in vehicle miles 
traveled (VMT), and strong economic conditions, CO levels decreased. 
The demonstration also examined wintertime meteorological data for the 
years 1998 through 2007 to determine if favorable meteorology 
influenced CO levels. The data showed that only a few periods had 
favorable meteorology. See pages 5-1 through 5-10 of the Las Vegas 
Valley CO Maintenance Plan.
    Thus, we find that the improvement in CO air quality in Las Vegas 
Valley is the result of permanent and enforceable emissions reductions 
from a combination of the Federal Motor Vehicle Control Program and 
EPA-approved State and local control measures. As such, we propose to 
find that the criterion for redesignation set forth at CAA section 
107(d)(3)(E)(iii) is satisfied.

D. The Area Must Have a Fully Approved Maintenance Plan Under CAA 
Section 175A

    Section 175A of the CAA sets forth the elements of a maintenance 
plan for areas seeking redesignation from nonattainment to attainment. 
We interpret this section of the Act to require, in general, the 
following core elements: attainment inventory, maintenance 
demonstration, monitoring network, verification of continued 
attainment, and contingency plan. See Calcagni memo, pages 8 through 
13.
    Under CAA section 175A, a maintenance plan must demonstrate 
continued attainment of the applicable NAAQS for at least ten years 
after EPA approves a redesignation to attainment. Eight years after 
redesignation, the State must submit a revised maintenance plan that 
demonstrates continued attainment for the subsequent ten-year period 
following the initial ten-year maintenance period. To address the 
possibility of future NAAQS violations, the maintenance plan must 
contain such contingency provisions, that EPA deems necessary, to 
promptly correct any violation of the NAAQS that occurs after 
redesignation of the area. Based on our review and evaluation of the 
plan, as detailed below, we are proposing to approve the Las Vegas 
Valley CO Maintenance Plan because we believe that it meets the 
requirements of CAA section 175A.
1. Attainment Inventory
    The plan must contain an attainment year emissions inventory to 
identify a level of emissions in the area that is sufficient to attain 
the CO NAAQS. This inventory is to be consistent with EPA's most recent 
guidance on emissions inventories for nonattainment areas available at 
the time and should represent emissions during the time period 
associated with the monitoring data showing attainment. The inventory 
should also be based on actual ``CO season data'' (i.e., wintertime) 
emissions for an attainment year.
    In this case, we have already approved an ``attainment year'' 
emissions inventory in that we approved the 2006 emissions inventory 
contained in the 2005 CO plan. The emissions inventories in the Las 
Vegas Valley CO Maintenance Plan represent updates to the previously 
approved emissions inventories in the 2005 CO Plan. As with the 
previous plan, the emission inventories in the Las Vegas Valley CO 
Maintenance are comprehensive, including emissions from stationary 
point sources, area sources, nonroad mobile sources, and on-road mobile 
sources, and represent CO season data (weekday in December). As was the 
case with the inventories in the 2000 and 2005 CO attainment plans for 
Las Vegas Valley, the CO inventories in the Maintenance Plan are not 
used directly to demonstrate maintenance of the CO standard, but they 
reflect the same methods, factors, and assumptions used to develop the 
CO emission rates used for the dispersion modeling analysis which 
provides the basis for the maintenance demonstration.
    As noted in our proposed approval of the 2005 CO Plan, the 2005 CO 
Plan provided a comprehensive revision to the base year (1996) 
emissions inventory and future year emissions projections reflecting 
updated underlying data, such as population and VMT forecasts, and 
updated methods, such as MOBILE6.2 and NONROAD2004. The 2005 CO Plan 
presented an emissions inventory for years 2006, 2010, 2015, 2020, and 
2030. The Las Vegas Valley CO Maintenance Plan presents emissions 
inventories for 2008, 2010, and 2020 that were developed using similar 
emissions calculations procedures, models, and assumptions as were used 
for the 2005 CO Plan (and described in detail in our proposed approval 
of the 2005 CO Plan at 71 FR 26910, at 26913-26915, May 9, 2006), but 
that were revised to reflect use of:
     Updated population and vehicle activity projections 
developed by the Regional Transportation Commission (RTC) (from RTC's 
FY2006-2030 Regional Transportation Plan, approved by RTC in October 
2006);
     Updated TransCAD travel demand model output from RTC;
     Revised wintertime gasoline properties that assume 
relaxation of the RVP limit from 9.0 psi to 13.5 psi, and suspension of 
the County's CBG Rule (i.e., suspension of the local sulfur content and 
aromatic hydrocarbon limits);\13\
---------------------------------------------------------------------------

    \13\ The revised wintertime gasoline specifications were used in 
developing the emissions inventories in the Maintenance Plan to 
calculate CO emissions from both on-road and nonroad gasoline-
powered vehicles.
---------------------------------------------------------------------------

     An updated emissions factor model (NONROAD2005, Core Model 
Version 2005a, February 2006) to estimate emissions for the nonroad 
source category; and
     Updated emissions information for Nellis Air Force Base.

In addition, the emissions projections in the Las Vegas Valley CO 
Maintenance Plan take no credit for the RTC's TCM program or the 
State's alternative fuels for government vehicles program. More 
detailed descriptions of the 1996 base year inventory, the 2008 
projected inventory, and the 2010 and 2020 projected inventory are 
documented in the Las Vegas Valley CO Maintenance Plan on pages 7-2 
through 7-8, and in the plan's Technical Support Document (attached to 
the plan as appendix B).
    We have summarized the emissions projections in table 2, below. As 
shown

[[Page 44745]]

in table 2, on-road mobile sources would continue to dominate CO 
emissions within the nonattainment area through the initial maintenance 
period (i.e., 10 years beyond redesignation). The 2005 CO Plan 
estimated on-road CO emissions at approximately 441 tons per day (see 
table 3-12 of the 2005 plan) for year 2006, and the increase in CO 
emissions from on-road mobile sources for 2008, 2010, and 2020 as shown 
in table 2 (relative to 2006) reflects the change in wintertime 
gasoline specifications, as described above. The change in wintertime 
gasoline specifications has not yet occurred, and will not occur until 
EPA approves the suspension/relaxation of the State and local gasoline 
rules, as proposed herein, thus, the emissions projections shown in 
table 2 below overestimate emissions that actually occurred in year 
2008. Aggregate emissions of CO are expected to hold steady, or to 
increase slightly, over the course of the initial maintenance period.

                                Table 2--Summary of CO Emissions in Tons per Day
                                           [For a weekday in December]
----------------------------------------------------------------------------------------------------------------
                                                                       2008            2010            2020
----------------------------------------------------------------------------------------------------------------
Point sources...................................................            15.8            15.8            15.8
Area sources....................................................            13.9            14.7            18.6
Aviation........................................................            39.7            42.2            53.5
Railway.........................................................             0.3             0.3             0.4
Non-road mobile sources.........................................            57.7            60.8            71.2
On-road mobile sources..........................................           579.3           579.7           574.4
                                                                 -----------------------------------------------
    Total.......................................................           706.7           713.5           733.9
----------------------------------------------------------------------------------------------------------------
Source: See Las Vegas Valley CO Maintenance Plan, Table 7-3.

    Based on our review and prior approval of the emissions inventories 
(and related documentation) from the 2005 CO plan, and our review of 
the changes to the earlier-approved inventories, we find that the 2006 
emission inventory from the 2005 CO Plan suffices as an attainment 
inventory for Las Vegas Valley, and that the emissions inventories in 
the Maintenance Plan reflect the latest planning assumptions and 
emissions models and provide a comprehensive and reasonably accurate 
forecast of CO emissions in Las Vegas Valley for years 2010 and 2020. 
As described in the next section in this document, dispersion modeling 
results derived from the same emissions methods, factors and 
assumptions used to develop the inventories provide the basis for the 
demonstration of maintenance of the CO NAAQS through 2020.
2. Maintenance Demonstration
    CAA section 175A(a) requires that the maintenance plan ``provide 
for the maintenance of the national primary ambient air quality 
standard for such air pollutant in the area concerned for at least 10 
years after the redesignation.'' Generally, a State may demonstrate 
maintenance of the CO NAAQS by either showing that future emissions 
will not exceed the level of the attainment inventory or by modeling to 
show that the future mix of sources and emissions rates will not cause 
a violation of the NAAQS. For areas that are required under the Act to 
submit modeled attainment demonstrations, the maintenance demonstration 
should use the same type of modeling. Calcagni memorandum, page 9. 
Because the attainment demonstration for Las Vegas Valley in the 2000 
CO Plan, and revised in the 2005 CO Plan, relied upon modeling 
techniques, the CO Maintenance Plan also relies on modeling techniques 
to demonstrate maintenance of the standard through the initial 
maintenance period.
    The Las Vegas Valley CO Maintenance Plan builds upon, and updates, 
previous modeling efforts conducted, most recently, in support of 
attainment demonstration in the 2005 CO Plan. Like the previous 
approved plan, the maintenance plan includes both area-wide modeling 
analysis and micro-scale modeling analyses at heavily-traveled 
intersections and local airports. As before, area-wide analysis, was 
conducted using the Urban Airshed Model (UAM), and the micro-scale 
analyses were conducted using CAL3QHC for local intersections, and the 
Emissions Dispersion Modeling System (EDMS) for the local airports. 
Generally, the micro-scale analyses combine the results of UAM modeling 
with those using either CAL3QHC (for intersections) or EDMS (for 
airports) to generate worst-case maximum CO concentrations in the 
various analysis years. The maintenance demonstration is discussed on 
pages 7-6 through 7-14 of the Maintenance Plan, and at more length in 
appendix B to the plan.
    The Maintenance Plan provides an area-wide UAM-based modeling 
demonstration of maintenance from year 2008 through year 2020 using 
December 8-9, 1996 episode conditions (which is the same episode used 
in the 2000 and 2005 CO plans) to determine peak CO concentrations. The 
UAM modeling for the Maintenance Plan uses updated emission inventories 
(see table 2, above) that reflect continued implementation of those 
control measures that are being retained for CO maintenance purposes, 
including the State's vehicle I/M program and the county's wintertime 
oxygenated gasoline program. The concentration estimates are shown in 
table 3, below. The estimates in table 3 do not include any CO 
emissions reductions from those measures in the maintenance plan that 
are identified as contingency measures, such as the State's Low RVP 
Rule and the County's CBG Rule.
    In the area-wide modeling demonstration, spatial patterns of 
predicted 8-hour CO are similar to those predicted by previous modeling 
in the 2005 CO plan. While the CO concentrations estimated for the 
Maintenance Plan are higher than those estimated in previous modeling 
completed for the 2005 CO Plan (due to the suspended/relaxed gasoline 
requirements assumed for the maintenance plan), they are below the 8-
hour CO standard of 9 ppm and decrease over time. Also, as in previous 
modeling, the area-wide impact of McCarran Airport increases over time 
with peak values increasing around the airport due to growth in airport 
activities.

[[Page 44746]]

Table 3--Las Vegas Valley CO Maintenance Plan Area-Wide Modeling Results
                    [Peak 8-hour UAM concentrations]
------------------------------------------------------------------------
                                                           Concentration
                          Year                                 (ppm)
------------------------------------------------------------------------
2008....................................................             8.8
2010....................................................             8.5
2020....................................................             7.7
------------------------------------------------------------------------
Source: Table 7-4 of the Las Vegas Valley CO Maintenance Plan.

    As noted above, in addition to the area-wide modeling effort, two 
micro-scale models, CAL3QHC and EDMS, were used to predict maximum CO 
concentrations at potential hot spot receptors at heavily traveled 
intersections and at local area airports. CAL3QHC is used to predict 
the micro-scale impacts of vehicles operating at congested 
intersections. Vehicles operating under congested conditions spend more 
time in idle mode that can contribute to high levels of CO near the 
roadways. As in the 2005 CO plan, micro-scale modeling was completed 
for three intersections (1) Eastern Avenue/Charleston Blvd., (2) 
Eastern Avenue/Fremont Street, and (3) Fremont Street/Charleston Blvd. 
These three intersections comprise the ``5 points'' area, which is near 
the Sunrise Acres CO monitoring station. Traffic data from the 2005 CO 
Plan were scaled based on updated TransCAD transportation modeling 
outputs and combined with emission factors from MOBILE6.2 and worst-
case meteorological data to predict local hotspot concentrations. These 
hourly results from the micro-scale model were then combined with 
hourly concentrations from the background UAM grid cell to compute 
maximum running 8-hour concentrations. The combined results from 
CAL3QHC and UAM are shown in table 4, below.

      Table 4--Las Vegas Valley CO Maintenance Plan Maximum Predicted Combined Modeling Results at Selected
                                                  Intersections
                                         [Peak 8-hour CO concentrations]
----------------------------------------------------------------------------------------------------------------
                                                                                       Year
                          Intersection                           -----------------------------------------------
                                                                       2008            2010            2020
----------------------------------------------------------------------------------------------------------------
Eastern Ave./Charleston Blvd....................................             8.1             7.7             6.9
Eastern Ave./Fremont St.........................................             7.7             7.4             6.7
Fremont St./Charleston Blvd.....................................             7.0             6.7             6.0
----------------------------------------------------------------------------------------------------------------
Source: Table 3-2 in appendix B to the Las Vegas Valley CO Maintenance Plan.

    To model the impact of airport sources, EDMS was used again as in 
the 2005 CO Plan. This model was developed for evaluating the specific 
emission sources typically located at airports. The hotspot results 
from EDMS were combined with the results of the UAM analysis to predict 
the concentrations at receptors around the airports. The Maintenance 
Plan presents the results of the combined UAM and EDMS models for all 
the future years in table 3-3 of appendix B. No values were modeled 
above the 9.0 ppm CO standard at any publicly accessible receptor 
location. The peak combined concentration at McCarran International 
Airport for future years is 8.9 ppm for 2020.
    Lastly, UAM was used to identify a safety margin \14\ to be 
included in the on-road motor vehicle emissions budgets to facilitate 
future transportation conformity determinations for CO during the 
initial maintenance period. See section V.D.7 of this document for 
EPA's review and proposed approval of the budgets in the Las Vegas 
Valley CO Maintenance Plan.
---------------------------------------------------------------------------

    \14\ The term ``safety margin'' refers to the amount by which 
the total projected emissions from all sources of a given pollutant 
are less than the total emissions that would satisfy the applicable 
requirement for reasonable further progress, attainment or 
maintenance. See 40 CFR 93.101.
---------------------------------------------------------------------------

    To identify a safety margin consistent with maintenance of the CO 
standard through the initial maintenance period, the maintenance plan 
scaled up the on-road motor vehicle emissions initially estimated and 
used for concentration modeling purposes (see table 2 above) over the 
entire modeling domain to the point at which the peak 8-hour CO 
concentration reached 8.9 ppm in 2008, 2010, and 2020. The on-road 
motor vehicle emissions outside the central urban sub-domain were then 
increased by an additional 60% in each year to reach a maximum peak 8-
hour CO concentration of just under 9.0 ppm in the peak UAM grid cell, 
at peak UAM plus CAL3QHC receptor, or at the peak UAM plus EDMS 
receptor. See pages 3-11 through 3-16 of appendix B to the Maintenance 
Plan.
    The target CO concentration was reached at the point where on-road 
motor vehicle emissions were increased to 658 tpd (13% higher than 
baseline 2008 on-road emissions), 686 tpd (18% higher), and 704 tpd 
(23% higher), in 2008, 2010, and 2020, respectively. See table 3-5 of 
appendix B to the Maintenance Plan. The corresponding peak 8-hour 
modeled concentrations (assuming this higher level of on-road motor 
vehicle emissions) ranged from 8.87 ppm in 2008 to 8.98 ppm in 2020. 
The 2020 value reflects microscale analysis (combining UAM plus EDMS) 
for a receptor at McCarron Airport. We find this procedure to be a 
reasonable means to identify an acceptable safety margin for CO 
emissions in Las Vegas Valley.
    Based on our review of the documentation provided in the CO 
maintenance plan as summarized above, we find that the revised modeling 
results are consistent with the underlying emission estimates and 
reflect reasonable methods and assumptions. Further, we find that the 
revised modeling results demonstrate continued maintenance of the CO 
NAAQS in Las Vegas Valley through 2020.
3. Monitoring Network
    Continued ambient monitoring of an area is generally required over 
the maintenance period. As discussed in section V.A of this document, 
CO is currently monitored by Clark County DAQEM at five stations within 
Las Vegas Valley. In the Las Vegas Valley CO Maintenance Plan (see page 
7-15 of the plan), Clark County DAQEM indicates its intention to 
continue operation of an air quality monitoring network consistent with 
EPA's monitoring requirements in 40 CFR part 58 (``Ambient Air Quality 
Surveillance'') to verify continued attainment of the CO NAAQS within 
Las Vegas Valley. The Las Vegas Valley CO Maintenance Plan also states 
that, in addition, Clark County DAQEM's CO monitoring network will be 
reviewed annually pursuant to 40 CFR 58.10 to determine

[[Page 44747]]

whether the system continues to meet the monitoring objectives in 40 
CFR part 58, appendix D. We find the County's commitment for continued 
ambient CO monitoring as set forth in the Las Vegas Valley CO 
Maintenance Plan to be acceptable.
4. Verification of Continued Attainment
    NDEP, the State Board of Agriculture, and the Clark County Board of 
County Commissioners have the legal authority to implement and enforce 
the requirements of the Las Vegas Valley CO Maintenance Plan. This 
includes the authority to adopt, implement and enforce any emission 
control contingency measures determined to be necessary to correct CO 
NAAQS violations. To verify continued attainment, Clark County DAQEM 
commits in the Maintenance Plan to the continued operation of a CO 
monitoring network that meets EPA monitoring requirements, and also to 
conduct studies to determine whether additional or re-sited CO monitors 
are necessary in response to measured changes in mobile source 
parameters (e.g., VMT, fleet mix). See page 7-15 of the Las Vegas 
Valley CO Maintenance Plan. This is acceptable.
5. Contingency Provisions
    Section 175A(d) of the Act requires that maintenance plans include 
contingency provisions, as EPA deems necessary, to promptly correct any 
violations of the NAAQS that occur after redesignation of the area. 
Such provisions must include a requirement that the State will 
implement all measures with respect to the control of the air pollutant 
concerned which were contained in the SIP for the area before 
redesignation of the area as an attainment area.
    Under section 175A(d), contingency measures identified in the 
contingency plan do not have to be fully adopted at the time of 
redesignation. However, the contingency plan is considered to be an 
enforceable part of the SIP and should ensure that the contingency 
measures are adopted expeditiously once they are triggered by a 
specified event. The maintenance plan should clearly identify the 
measures to be adopted, a schedule and procedure for adoption and 
implementation, and a specific timeline for action by the State. As a 
necessary part of the plan, the State should also identify specific 
indicators or triggers, which will be used to determine when the 
contingency measures need to be implemented.
    The Las Vegas Valley CO Maintenance Plan identifies four specific 
contingency measures: RTC's TDM/TCM program, the State's Alternative 
Fuels for Government Fleets Program, Clark County's CBG Rule, and the 
State's Low RVP Rule. All of these measures have been approved by EPA 
into the SIP and are currently in effect. The first two measures would 
remain in effect but are identified as ``contingency measures'' in the 
Maintenance Plan because the maintenance demonstration takes no 
emissions credit for these programs. EPA has concluded that contingency 
measures need not be new measures that would be triggered by a 
violation, but may consist of early implementation of measures that 
provide surplus reductions beyond those needed for attainment or 
maintenance. See ``Early Implementation of Contingency Measures for 
Ozone and Carbon Monoxide (CO) Nonattainment Areas,'' memorandum from 
G.T. Helms to EPA Air Branch Chiefs, August 13, 1993. Identification of 
RTC's TDM/TCM program and the State's Alternative Fuels for Government 
Fleets Program as contingency measures in the Las Vegas Valley CO 
Maintenance Plan is acceptable because, based on the rationale 
presented above, we believe that the Maintenance Plan adequately 
demonstrates maintenance of the CO NAAQS without taking any credit for 
these two measures.
    With respect to the Clark County's CBG Rule and the State Board of 
Agriculture's Low RVP Rule, we are proposing to approve the suspension 
of the former, and the relaxation of the latter, in this document. As 
noted above, contingency provisions must include a requirement that the 
State will implement all measures with respect to the control of the 
air pollutant concerned which were contained in the SIP for the area 
before redesignation of the area as an attainment area. In this 
instance, Clark County's CBG Rule and the State's Low RVP Rule are two 
measures that were contained in the SIP prior to redesignation and thus 
must be included as contingency measures in the maintenance plan. The 
Maintenance Plan does in fact list both measures as contingency 
measures (see page 5-8 of the Maintenance Plan), and we believe that, 
by adopting the Las Vegas Valley CO Maintenance Plan, Clark County has 
adequately committed to reinstate the suspended fuels program, if 
necessary in light of a monitored violation of the CO NAAQS, and 
thereby implement the related contingency measure. The State Department 
of Agriculture has yet to specifically commit to seek reinstatement by 
the Board of Agriculture of the Low RVP Rule if needed to remedy future 
CO NAAQS violations in Las Vegas Valley. Based on our discussions with 
Clark County, NDEP and the Department of Agriculture, however, we 
expect that such a commitment from the Department of Agriculture will 
be forthcoming in the near future, and we will not finalize our 
proposed approval of the Maintenance Plan and redesignation request 
unless and until we receive and approve the State's submittal of this 
commitment as a revision to the Nevada SIP.
    The contingency provisions of the Las Vegas Valley CO Maintenance 
Plan (see pages 7-15 and 7-16 of the plan) are triggered upon the 
occurrence of an exceedance of the 8-hour CO standard (i.e., a 
monitored level of 9.5 ppm or greater) at any of the monitoring 
stations in the area. Upon such an occurrence, Clark County DAQEM will 
review and verify the monitoring data within three months, and 
recommend contingency measures within six months. The types of 
contingency measures envisioned under these circumstances would be 
local, voluntary measures.
    However, if a second exceedance occurs at the same monitoring site 
within a consecutive two-year period, DAQEM will make a recommendation 
to the Clark County Board of County Commissioners (within six months of 
the second exceedance) from among those contingency measures 
specifically listed in the Maintenance Plan, as described above, 
including reinstatement of Clark County's CBG Rule and reinstatement of 
the State's Low RVP Rule. The Maintenance Plan would not require 
implementation of these contingency measures unless the area 
experiences a violation of the 8-hour CO NAAQS (i.e. a second 
exceedance at the same site during the same calendar year). The 
Maintenance Plan states that the contingency measures will be 
implemented six to 12 months after approval by the Clark County Board 
of Commissioners, depending on the time needed to put the measures in 
place. See page 7-16 of the Maintenance Plan.
    Upon our review of the plan, as summarized above, we find that the 
contingency provisions of the Maintenance Plan clearly identify 
specific contingency measures, contain tracking and triggering 
mechanisms to determine when contingency measures are needed, contain a 
description of the process of recommending and implementing contingency 
measures, and contain specific timelines for action. Thus, we conclude 
that, with the exception of the absence of a commitment by the State 
Department of

[[Page 44748]]

Agriculture to seek reinstatement by the Board of Agriculture of the 
Low RVP Rule, the contingency provisions of the Las Vegas Valley CO 
Maintenance Plan are adequate to ensure prompt correction of a 
violation and therefore comply with section 175A(d) of the Act. We will 
not take final action to approve the Maintenance Plan until we receive 
the commitment by the State Department of Agriculture to seek 
reinstatement of the Low RVP Rule if needed to remedy a future CO NAAQS 
violation in Las Vegas Valley.\15\
---------------------------------------------------------------------------

    \15\ On July 12, 2010, the Nevada Department of Agriculture 
initiated a 30-day comment period to solicit comment (or request a 
public hearing) on the draft commitment regarding implementation of 
the contingency measure in the Maintenance Plan related to 
reinstatement of the Low RVP Rule. The Department's notice of intent 
to solicit public comment, which includes the commitment language, 
has been placed in the docket for this rulemaking. We have reviewed 
the language of the Department's draft commitment and expect to 
approve it if it is ultimately submitted to us without significant 
modification.
---------------------------------------------------------------------------

6. Subsequent Maintenance Plan Revisions
    CAA section 175A(b) provides that States shall submit a SIP 
revision 8 years after redesignation providing for maintaining the 
NAAQS for an additional 10 years. The Las Vegas Valley CO Maintenance 
Plan provides that Clark County DAQEM will prepare a revised 
maintenance plan eight years after redesignation to attainment. See 
page 7-17 of the Maintenance Plan.
7. Motor Vehicle Emissions Budgets
    Transportation conformity is required by section 176(c) of the CAA. 
Our transportation conformity rule (codified in 40 CFR part 93, subpart 
A) requires that transportation plans, programs, and projects conform 
to SIPs and establishes the criteria and procedures for determining 
whether or not they do so. Conformity to the SIP means that 
transportation activities will not produce new air quality violations, 
worsen existing violations, or delay timely attainment of the national 
ambient air quality standards.
    Maintenance plan submittals must specify the maximum emissions of 
transportation-related CO emissions allowed in the last year of the 
maintenance period, i.e., the motor vehicle emissions budget (MVEB). 
The submittal must also demonstrate that these emissions levels, when 
considered with emissions from all other sources, are consistent with 
maintenance of the NAAQS. In order for us to find these emissions 
levels or ``budgets''adequate and approvable, the submittal must meet 
the conformity adequacy provisions of 40 CFR 93.118(e)(4) and (5). For 
more information on the transportation conformity requirement and 
applicable policies on MVEBs, please visit our transportation 
conformity Web site at: http://www.epa.gov/otaq/stateresources/
transconf/index.htm.
    The Las Vegas Valley CO Maintenance Plan includes the CO MVEBs 
shown in table 5 below. The budgets are based on table 7-9 of the 
Maintenance Plan and other documentation in section 7.5 of the plan. 
See also the discussion of projected emissions in section V.D.2 
(``Maintenance Demonstration'') of this document.

 Table 5--Las Vegas Valley CO Maintenance Plan, Motor Vehicle Emissions
                                 Budgets
               [Winter weekday emissions in tons per day]
------------------------------------------------------------------------
                          Year                                 MVEB
------------------------------------------------------------------------
2008....................................................             658
2010....................................................             686
2020....................................................             704
------------------------------------------------------------------------

    In setting MVEBs, States generally use the on-road motor vehicle 
portion of the emission inventories in the associated plan. Clark 
County, however, did not cap MVEBs at projected motor vehicle emissions 
levels. Because overall projected levels of emissions from all sources 
are expected to be significantly less than the levels necessary to 
maintain the CO NAAQS, Clark County scaled up emissions in the 
maintenance demonstration to set MVEBs at a higher level. As long as 
emissions from all sources are lower than needed to provide for 
continued maintenance of the standard, the State may allocate 
additional emissions to future mobile source growth by assigning a 
portion of the safety margin to the MVEBs (see 40 CFR 93.124).
    The criteria by which we determine whether a SIP's MVEBs are 
adequate and approvable for conformity purposes are outlined in 40 CFR 
93.118(e)(4) and (5). The following paragraphs provide our review of 
the budgets in the Las Vegas Valley CO Maintenance Plan against our 
adequacy criteria and provide the basis for our proposed approval of 
the MVEBs.
    Under 40 CFR 93.118(e)(4)(i), we review a submitted plan to 
determine whether the plan was endorsed by the Governor (or designee) 
and was subject to a public hearing. The Las Vegas Valley CO 
Maintenance Plan was submitted to EPA on September 18, 2008 by NDEP's 
Administrator, the Governor of Nevada's designee for all SIP revision 
submittals. This SIP submittal documents that the Clark County Board of 
Commissioners held a public hearing on the plan on September 2, 2008, 
and adopted the plan on that same date. Therefore, we conclude that the 
plan and related budgets meet the criterion under 40 CFR 
93.118(e)(4)(i).
    Under 40 CFR 93.118(e)(4)(ii), we review a submitted plan to 
determine whether the plan was developed through consultation with 
Federal, State and local agencies, whether full implementation plan 
documentation was provided to EPA, and whether EPA's stated concerns, 
if any, were addressed. Consultation for development of this plan 
largely consisted of public meetings (see appendix C to the Maintenance 
Plan); discussions with Federal, State, and local transportation 
planning agencies; and a public hearing, preceded by notices that were 
published in a newspaper of general circulation. Documentation was 
provided to EPA, and EPA's stated concerns were addressed. We conclude 
that adequate consultation occurred prior to submittal of the 
Maintenance Plan to EPA, and that EPA's concerns were adequately 
addressed for the purposes of 40 CFR 93.118(e)(4)(ii).
    Under 40 CFR 93.118(e)(4)(iii), we review a submitted plan to 
determine whether the MVEBs are clearly identified and precisely 
quantified. The Maintenance Plan clearly identifies and precisely 
quantifies the CO MVEBs for the years 2008, 2010 and 2020 on page 7-15 
of the plan (and table 5, above). We conclude therefore that the plan 
and related budgets meet the adequacy criterion under 40 CFR 
93.118(e)(4)(iii).
    Under 40 CFR 93.118(e)(4)(iv), we review a submitted plan to 
determine whether the MVEBs, when considered together with all other 
emissions sources, are consistent with applicable requirements for 
reasonable further progress, attainment, or maintenance (whichever is 
relevant to a given SIP submission). The Maintenance Plan shows how the 
MVEBs and related safety margins are consistent with maintenance of the 
CO NAAQS through 2020 (see pages 7-6 through 7-15 of the Maintenance 
Plan). In particular, Tables 7-6, 7-7, 7-8, and 7-9 of the Maintenance 
Plan show the extent to which maximum future year emissions (including 
the budget safety margins) fall below ambient concentration levels for 
the 8-hour CO NAAQS. Consequently, we find that the plan and related 
budgets meet this criterion for adequacy.

[[Page 44749]]

    Under 40 CFR 93.118(e)(4)(v), we review a plan to determine whether 
the MVEBs are consistent with and clearly related to the emissions 
inventory and the control measures in the submitted control strategy 
plan or maintenance plan. The MVEBs in the Maintenance Plan 
appropriately reflect the measures relied upon for continued 
maintenance of the CO standard in Las Vegas Valley, including the 
wintertime oxygenated gasoline program and the State's vehicle I/M 
program, as well as the decision by State and Clark County to suspend 
or relax certain other wintertime gasoline requirements (i.e., suspend 
the CBG Rule and relax the Low RVP Rule) and to take no CO credit for 
certain other measures (i.e., the Alternative Fuels for Government 
Fleets program and RTC's TDM/TCM program). Thus, we find that the MVEBs 
are consistent with and clearly related to the emissions inventory and 
the control measures in the submitted maintenance plan and thereby meet 
the criterion for adequacy under 40 CFR 93.118(e)(4)(v).
    Under 40 CFR 93.118(e)(4)(vi), we review a submitted plan to 
determine whether revisions to previously submitted plans explain and 
document any changes to previously submitted budgets and control 
measures; impacts on point and area source emissions; any changes to 
established safety margins; and reasons for the changes (including the 
basis for any changes related to emissions factors or estimates of 
vehicle miles traveled and changes in control measures). There are no 
previously submitted CO maintenance plans for the Las Vegas Valley. 
Changes in the MVEBs relative to the previously approved MVEBs from the 
attainment plans (i.e., the Las Vegas Valley 2000 CO Plan and then 
later from the Las Vegas Valley 2005 CO Plan) reflect updates to EPA's 
MOBILE model, RTC's planning assumptions regarding employment and 
population, and RTC's travel activity and fleet mix projections; the 
decision to establish safety margins for motor vehicle emissions; and 
the decision to take no CO emission reduction credit for certain 
control measures (e.g., CBG Rule and Low RVP Rule). Thus, we find that 
the Maintenance Plan meets the criterion for adequacy under 40 CFR 
93.118(e)(4)(vi).
    Under 40 CFR 93.118(e)(5), we review the State's compilation of 
public comments and response to comments that are required to be 
submitted with any SIP revision. Appendix C of the Maintenance Plan 
submittal documents the notice for public comments on the draft 
Maintenance Plan and documents the proceedings at the public hearing. 
The only comments on the draft Maintenance Plan were submitted by EPA, 
and appendix C (to the Maintenance Plan) documents how the draft 
Maintenance Plan was amended in response to those comments. We find 
Clark County DAQEM's responses to our comments on the draft plan to be 
acceptable, and thus, we find that the Maintenance Plan meets the 
criterion for adequacy under 40 CFR 93.118(e)(5).
    For the reasons set forth above, we find that the MVEBs in the Las 
Vegas Valley CO Maintenance Plan meet the requirements under 40 CFR 
93.118(e)(4) and (5), and that the maintenance plan as a whole will 
ensure maintenance of the CO NAAQS through the last year of the 
maintenance plan. Thus, we propose to approve the motor vehicle 
emissions budgets for transportation conformity purposes. If we 
finalize our action as proposed, RTC (which is the area's Metropolitan 
Planning Organization) and the U.S. Department of Transportation will 
be required to use the CO MVEBs from the Maintenance Plan for future 
transportation conformity determinations.\16\
---------------------------------------------------------------------------

    \16\ The current approved CO motor vehicle emissions budgets 
from the 2005 CO (Attainment) Plan are: 690, 768, and 817 tons per 
winter weekday for 2010, 2015, and 2015, respectively. See 71 FR 
44587 (August 7, 2006). The Maintenance Plan does not explicitly 
indicate that the budgets set forth therein are intended to replace 
the budgets from the 2005 CO Plan. Thus, if EPA takes final action 
to approve the Maintenance Plan budgets as proposed, then both sets 
of budgets (i.e., those from the 2005 CO Plan, and those from the 
Maintenance Plan) would apply because they relate to different CAA 
requirements for the same years. As a practical matter, however, the 
Maintenance Plan budgets, being lower than the 2005 CO Plan budgets, 
would be the constraining budgets for determining conformity.
---------------------------------------------------------------------------

    EPA generally first reviews budgets submitted with an attainment, 
RFP, or maintenance plan for adequacy, prior to taking action on the 
plan itself. The availability of the Las Vegas CO Maintenance Plan with 
the 2008, 2010, and 2020 budgets was announced for public comment on 
EPA's adequacy Web page on September 30, 2008, at: http://www.epa.gov/
otaq/transp/conform/adequacy.htm. The public comment period on the 
adequacy of the budgets closed on October 30, 2008. EPA did not receive 
any comments on the budgets, but did not complete the process and make 
an adequacy determination on the budgets. Instead, we are now proposing 
to approve the budgets.
8. Conclusion
    For the reasons set forth above, we find that the Las Vegas Valley 
CO Maintenance Plan satisfies the applicable CAA requirements, 
including CAA section 175A, and thus, we propose to approve it as a 
revision to the Nevada SIP under section 110(k)(3), contingent upon 
receipt of a commitment from the State Department of Agriculture to 
seek reinstatement by the State Board of Agriculture of the Low RVP 
Rule if needed to remedy a future violation of the CO NAAQS in Las 
Vegas Valley.

VI. Evaluation of Suspended or Relaxed Wintertime Gasoline 
Specifications

    As noted previously, NDEP's March 26, 2010 SIP revision includes an 
amended State fuels rule that relaxes the existing wintertime gasoline 
requirement for RVP (referred to herein as the ``Low RVP Rule''), and 
includes the suspension by Clark County of their local Cleaner Burning 
Gasoline (CBG) rule (referred to herein as the ``CBG Rule''). The CBG 
Rule established sulfur and aromatics limits for gasoline sold in Clark 
County during the period from November 1 to March 31.
    On December 9, 2009, the State Board of Agriculture amended NAC 
section 590.065 (i.e., the Low RVP Rule) to incorporate updated ASTM 
standard specifications and to relax the vapor pressure limit for 
wintertime gasoline sold in Clark from 9.0 psi to 13.5 psi.\17\ EPA 
first approved the Low RVP Rule as a revision to the Nevada SIP in 2004 
when EPA approved the rule as a CO control measure of the 2000 CO Plan. 
See 69 FR 56351 (September 21, 2004). EPA's proposed approval of the 
Low RVP Rule (68 FR 4141, January 28, 2003) describes how lower vapor 
pressure in gasoline reduces CO emissions and the relative magnitude in 
the corresponding reduction in vehicular CO emissions. Please see EPA's 
January 28, 2003 proposed rule for additional information on this topic 
at 68 FR 4141, 4150-4151.
---------------------------------------------------------------------------

    \17\ The State's wintertime vapor pressure limit (raised from 
9.0 psi to 13.5 psi) would continue to apply to gasoline sold within 
Clark County from October 1st through March 31st. Another revision 
to the rule would extend the wintertime vapor pressure limit in 
Clark County to ``any blend of gasoline and ethanol.''
---------------------------------------------------------------------------

    In our 2003 proposed approval of the Low RVP Rule, we considered 
whether the RVP specification is preempted under the Act. Section 
211(c)(4)(A) preempts certain State fuel regulations by prohibiting a 
State from prescribing or attempting to enforce ``any control or 
prohibition respecting any characteristic or component of a fuel or 
fuel additive'' for the purposes of motor vehicle emission control, if 
EPA has prescribed under section 211(c)(1), ``a control or prohibition 
applicable to such characteristic or component of the fuel or fuel 
additive,'' unless the State

[[Page 44750]]

control or prohibition is identical to the control or prohibition 
prescribed by EPA. In our 2003 proposed rule, we concluded that, 
because the Federal controls on RVP, promulgated under section 211(h) 
and section 211(c)(1), apply only in the summer months, there would be 
no Federal preemption of the State's Low RVP Rule. What was true in 
2003 remains true today. There is still no Federal RVP control 
applicable to gasoline in the wintertime, and thus, no Federal 
preemption of the relaxed vapor pressure limit (13.5 psi) established 
in amended NAC section 590.065.
    Further, in 2004, EPA approved CBG into the Nevada SIP. See 69 FR 
56351 (September 21, 2004). The CBG Rule is described in detail in 
EPA's proposed approval of the rule and the related 2000 CO Plan on 
January 28, 2003 (68 FR at 4151-4152). At the time, we also considered 
whether the sulfur content and aromatics limits for CBG were preempted 
under CAA section 211(c)(4)(C).\18\ As earlier explained, CAA section 
211(c)(4)(A) preempts certain State fuel regulations by prohibiting a 
State from prescribing or attempting to enforce ``any control or 
prohibition respecting any characteristic or component of a fuel or 
fuel additive'' for the purposes of motor vehicle emission control, if 
EPA has prescribed under section 211(c)(1), ``a control or prohibition 
applicable to such characteristic or component of the fuel or fuel 
additive,'' unless the State control or prohibition is identical to the 
control or prohibition prescribed by EPA. Further, under CAA section 
211(c)(4)(C), a State may prescribe and enforce an otherwise preempted 
fuel control if EPA approves the control into the State's SIP. In order 
to approve a preempted control into a SIP, EPA must find that the State 
control is necessary to achieve a NAAQS either because no other 
measures that would bring about timely attainment exist or that such 
measures exist but are either unreasonable or impracticable. CAA 
section 211(c)(4)(C) is intended to ensure that a State resorts to a 
fuel measure only if there are no available practicable and reasonable 
non-fuel measures, and in our 2004 approval of the CBG Rule, we found 
that Clark County's requirements for sulfur and aromatics limits were 
``necessary'' to achieve the CO NAAQS.
---------------------------------------------------------------------------

    \18\ The CBG Rule establishes a maximum sulfur content limit of 
80 ppm (by weight). With respect to sulfur content, producers and 
importers must also meet a 40 ppm flat limit or an average limit of 
30 ppm subject to the 80 ppm cap. The standards for aromatic 
hydrocarbons include a 30% cap (by volume), with producers and 
importers required to meet a 25% flat limit or an average limit of 
22% (subject to the 30% cap). The applicable geographic area is 
Clark County, and the applicable period for use of CBG is November 
1st through March 31st.
---------------------------------------------------------------------------

    In addition, the Energy Policy Act of 2005 (EPAct) amended section 
211(c)(4)(C) by including a number of provisions addressing State 
``boutique''fuel programs.\19\ The EPAct required EPA, in consultation 
with the Department of Energy, to determine the total number of fuels 
approved into all SIPs under section 211(c)(4)(C) as of September 1, 
2004, and to publish a list that identifies these fuels, the States and 
Petroleum Administration for Defense Districts (PADD) in which they are 
used. CAA section 211(c)(4)(C)(v)(II).
---------------------------------------------------------------------------

    \19\ While the phrase ``boutique''fuels programs can mean 
different things, it generally refers to State fuels programs that 
establish different requirements than the Federal fuels program 
required in a given area, typically for the purpose of addressing 
specific local air quality issues.
---------------------------------------------------------------------------

    On December 28, 2006, EPA published a notice containing the final 
interpretation, which was by fuel type, of the EPAct provisions in the 
Federal Register. See 71 FR 78192. We also determined and published a 
list of a total of eight (8) fuel types approved into SIPs, under 
section 211(c)(4)(C) as of September 1, 2004, the States and the PADD 
in which they are used. Clark County CBG, which as earlier explained 
has sulfur and aromatics content limits for gasoline in use during the 
period from November 1 to March 31, is on the list.
    The EPAct also placed the following three additional restrictions 
on EPA's authority to waive preemption by approving a State fuel 
program into SIPs under section 211(c)(4)(C):
     First, EPA may not approve a State fuel program into the 
SIP if it would cause an increase in the total number of fuel types 
approved into SIPs as of September 1, 2004.
     Second, in cases where EPA approval of a fuel would 
increase the total number of fuel types on the list but not above the 
number approved as of September 1, 2004, because the total number of 
fuel types in SIPs is below the number of fuel types as of September 1, 
2004, we are required to make a finding after consultation with DOE, 
that the new fuel will not cause supply or distribution interruptions 
or have a significant adverse impact on fuel producibility in the 
affected or contiguous areas.
     Third, with the exception of 7.0 psi RVP, EPA may not 
approve a State fuel into a SIP unless that fuel type is already 
approved in at least one SIP in the applicable PADD. CAA Section 
211(c)(4)(C)(v)(I), (IV) and (V).
    Therefore, EPAct also amended section 211(c)(4)(C) to make any new 
EPA approvals of State fuels under section 211(c)(4)(C) significantly 
more difficult by, for example, limiting the total number of approved 
``boutique'' fuel types to the number of fuel types approved into SIPs 
as of September 1, 2004. If there is no room on the list, for example, 
then EPA cannot approve any more boutique fuels regardless of the needs 
of a given area to address air pollution problems.
    Lastly, CAA section 211(c)(4)(C)(v)(III) requires EPA to remove a 
fuel from the boutique fuels list described above if a fuel either 
ceases to be included in a SIP or if a fuel in a SIP is identical to a 
Federal fuel formulation implemented by EPA. CBG will not cease to be 
included in the SIP because, as earlier discussed, CBG is currently in 
the SIP and will continue in the SIP as a specific contingency measure 
in the Las Vegas Valley CO Maintenance Plan, and because we intend to 
synchronize our final actions on the Maintenance Plan and the 
(suspended) CBG Rule (and thereby avoid a gap in time when the CBG Rule 
would not be either an active or contingency measure in the SIP). Thus, 
in today's action, we are not proposing to remove CBG from the boutique 
fuels list. In addition, since we are not approving any new fuel into 
the SIP under section 211(c)(4)(C), no issues are raised concerning the 
three restrictions on such an approval described above.
    As a general matter, under CAA section 110(l), EPA may approve 
relaxations or suspensions of control measures so long as doing so 
would not interfere with attainment or maintenance of any of the NAAQS 
or would otherwise conflict with applicable CAA requirements. In this 
instance, the relaxation of the Low RVP Rule and the suspension of the 
CBG Rule (and related sulfur and aromatics content limits) would not 
conflict with any applicable CAA requirement. However, the changes to 
the two fuels rules would affect the properties of the gasoline sold in 
Clark County during the winter and would thereby change vehicular 
emissions relative to those that would occur without these changes with 
concomitant effects on ambient pollutant concentrations (and 
potentially interfering with attainment or maintenance of the NAAQS).
    To specify the changes in the properties of wintertime gasoline due 
to the changes in the fuels rules, Clark County DAQEM commissioned a 
study by ENVIRON and Sierra Research. The study was submitted as 
appendix A to the Las Vegas Valley CO Maintenance Plan. As far as 
changes to sulfur content are concerned, the study authors predict

[[Page 44751]]

essentially no increase in gasoline sulfur content due to the 
applicability of Federal tier 2 gasoline sulfur limits [which are very 
similar (30 ppm average, with an 80 ppm cap) to the corresponding 
limits under the CBG rule]. We agree that any increase would be minimal 
due to the similarities between the Federal sulfur limits and those in 
the CBG Rule, and would expect the Federal gasoline sulfur content 
limits to essentially backstop the emissions reductions associated with 
the low sulfur content limit in the CBG Rule.
    As far as aromatics are concerned, the study predicts an increase 
in aromatic content from the current (2006) wintertime average of 
approximately 20% (by volume) to approximately 23%, based on the 
average aromatics content in gasoline nationwide. See page 12 of 
appendix A to the Maintenance Plan. Moreover, wintertime gasoline RVP 
could increase from the current (2006) average of 8.8 psi to as high as 
13.5 psi in response to the relaxation of the Low RVP Rule. The 
relative increases in aromatics and RVP would lead to higher emissions 
of CO and VOC, and potentially of particulate matter as well. We review 
these increases or potential increases, in the context of attainment 
and maintenance of the CO, ozone, and particulate matter NAAQS in the 
paragraphs that follow.
    With respect to CO, we conclude that the changes in wintertime 
gasoline specifications due to the rules changes would not interfere 
with the NAAQS based on the modeling results documented in the Las 
Vegas Valley CO Maintenance Plan and our proposed approval of the 
Maintenance Plan herein. The modeling conducted for the Maintenance 
Plan relies on emissions factors that take no credit for either the CBG 
Rule or the Low RVP Rule and still demonstrates maintenance of the CO 
NAAQS in Las Vegas Valley through 2020.
    For the ozone NAAQS, we recognize that a portion of Clark County is 
designated nonattainment for the 8-hour ozone NAAQS, and thus, absent 
modeling results or other convincing evidence showing non-interference, 
we would not normally approve a SIP revision that would result in an 
increase in ozone precursors within the nonattainment area. However, in 
the Las Vegas Valley CO Maintenance Plan, Clark County DAQEM contends 
that there would be no interference with the ozone NAAQS in this 
instance because the effect of the gasoline fuel changes is limited to 
the winter months whereas ozone exceedances occur during the 
summertime. See pages 6-2 and 6-3 of the Maintenance Plan. At the 
outset, we generally find this line of reasoning for a non-interference 
finding to be acceptable, but to gain a more detailed understanding of 
the seasonal nature of ozone exceedances in Las Vegas Valley, we 
reviewed ozone data by month to determine when exceedances of the 0.075 
ppm, eight-hour average, ozone NAAQS occurred. The data indicates that, 
over the past 6 years (2004-2009), all exceedances of the 0.075 ppm 
standard occurred during and between the months of April and September. 
Conversely, no ozone NAAQS exceedances were recorded from October 
through March, which is the period of time affected by the suspension 
of the CBG Rule and relaxation of the RVP specification. Thus, we find 
that the changes in Clark County wintertime gasoline specifications 
would not interfere with attainment or maintenance of the ozone NAAQS.
    With respect to the 1987 (24-hour average) PM-10, Las Vegas Valley 
is classified as a ``serious'' nonattainment area. See 40 CFR 81.329. 
In 2004, EPA approved the ``serious'' area PM-10 plan for Las Vegas 
Valley and approved the request to extend the applicable attainment 
date to the end of 2006. See 69 FR 32273 (June 9, 2004). In our 2004 
final rule approving the PM-10 plan, we approved a number of fugitive 
dust rules, including Clark County Air Quality Regulations (AQR) 
Sections 90 through 94, that limit emissions from such sources as open 
areas and vacant lots; unpaved roads, unpaved alleys and unpaved 
easement roads; unpaved parking lots; construction sites; and paved 
roads and street sweeping equipment. In approving the Las Vegas Valley 
``serious'' area PM-10 plan, we also indicated that we agreed with 
Clark County DAQEM's conclusion that nonroad and on-road vehicle 
exhaust are not significant source categories in Las Vegas Valley for 
the purpose of implementing Best Available Control Measures (BACM). See 
our proposed approval of the PM-10 plan at 68 FR 2954, at 2959 (January 
22, 2003).
    In the Las Vegas Valley CO Maintenance Plan, Clark County DAQEM 
contends that the changes in wintertime gasoline specifications would 
not interfere with the PM-10 NAAQS based on the determination in the 
approved serious area PM-10 plan that vehicular exhaust is not a 
significant source of PM-10 in Las Vegas Valley.\20\ See pages 6-3 and 
6-4 of the Maintenance Plan. Clark County DAQEM also contends that 
removing fuels controls has no impact on PM-10 emissions from vehicular 
exhaust. Lastly, Clark County DAQEM points to the most recent PM-10 
emissions inventory that shows vehicular exhaust to account for less 
than one percent of the total PM-10 emissions in Las Vegas Valley in 
year 2006.
---------------------------------------------------------------------------

    \20\ The significant source categories identified in the serious 
area PM-10 plan for Las Vegas Valley are fugitive types of sources, 
including disturbed vacant land/unpaved parking lots, construction 
(including highway construction), and vehicular travel on paved and 
unpaved roads. See 68 FR 2954, at 2959 (January 22, 2003).
---------------------------------------------------------------------------

    First of all, Clark County DAQEM is correct in pointing out that 
vehicular exhaust was determined not to be a significant source of PM-
10 emissions in Las Vegas Valley for the purposes of implementing the 
BACM requirement. We also believe that Clark County DAQEM's most recent 
inventory presents reasonable estimates of existing sources of PM-10 in 
Las Vegas Valley. As a general matter, we do not agree that removal of 
fuels controls has no affect on vehicular exhaust emissions of PM-10, 
but we recognize that the extent to which the higher aromatics content 
(from 20% to 23%, by volume) and higher RVP (from 8.8 to 13.5 psi) 
would affect PM-10 from vehicle exhaust, and whether that effect would 
be positive or negative, is difficult to predict because EPA's MOBILE 
emissions factor model, which was used in the development of the 
Maintenance Plan, does not have the capability to quantify the 
resulting emissions changes.
    However, even assuming the effect would be an increase in PM-10 
from vehicle exhaust, we can still find that the changes in wintertime 
gasoline specifications due to the fuels changes would not interfere 
with attainment of the PM-10 NAAQS, because, in addition to the minimal 
impact of vehicular emissions on PM-10 concentrations in Las Vegas 
Valley (based on PM-10 inventories), the area appears to have attained 
the standard due to the implementation and enforcement of fugitive dust 
controls. To determine whether Las Vegas Valley is attaining the PM-10 
standard, we reviewed 2007-2009 PM-10 monitoring data from the various 
monitoring stations for which Clark County DAQEM reports data into 
EPA's Air Quality Database (AQS). The review of the data reveals two 
exceedances (i.e., 24-hour-average concentrations equal to or greater 
than 155 [mu]g/m\3\) over the 2007-2009 period, both of which were 
recorded during year 2008 at the Craig Road PM-10 monitoring site in 
North Las Vegas. The PM-10 monitor at the Craig Road site is a 
continuous monitor,

[[Page 44752]]

and thus the expected number of days per year, averaged over the 2007-
2009 period, is less than 1.0,\21\ which means that the PM-10 NAAQS has 
been met at the Craig Road monitor, and since the Craig Road monitor is 
the only site recording any exceedances, it follows that the entire 
valley has attained the standard.\22\
---------------------------------------------------------------------------

    \21\ The PM-10 NAAQS is 150 micrograms per cubic meter ([mu]g/
m\3\), 24-hour average concentration. The standard is attained when 
the expected number of days per calendar year with a 24-hour average 
concentration above 150 [mu]g/m\3\, as determined in accordance with 
appendix K to 40 CFR part 50, is equal to or less than one. See 40 
CFR 50.6.
    \22\ An attainment finding is not the same as redesignation of 
an area to attainment. The latter type of action can only be 
approved by EPA if all of the criteria under CAA section 
107(d)(3)(E) are met, including submittal of, and EPA approval of, a 
maintenance plan.
---------------------------------------------------------------------------

    We do not believe that a hypothetical, incremental increase in PM-
10 emissions, from a source category (vehicular exhaust) estimated to 
contribute less than 1% to the overall emissions inventory, would have 
a discernible effect on ambient PM-10 concentrations. This lack of 
discernible effect, coupled with an attainment finding, provides us 
with a sufficient rationale for concluding that the changes in 
wintertime gasoline properties, expected to occur with the relaxation 
of the Low RVP Rule and the suspension of the CBG Rule, would not 
interfere with attainment or maintenance of the PM-10 NAAQS in Las 
Vegas Valley.
    With respect to the 1997 (annual) and 2006 (24-hour) PM-2.5 NAAQS, 
Las Vegas Valley and the various other hydrographic areas that comprise 
Clark County, are designated as ``unclassifiable/attainment'' areas. 
See 40 CFR 81.329. A review of AQS data from the various PM-2.5 
monitoring sites in Clark County reveals that PM-2.5 concentrations are 
well below the PM-2.5 NAAQS. Over the past three years, the highest 
98th percentile value (for the 24-hour average), recorded at the 
Sunrise Avenue site, is 23 [mu]g/m\3\, well below the corresponding 24-
hour NAAQS of 35 [mu]g/m\3\. The highest annual concentration, also 
recorded as the Sunrise Avenue site, is 10.3 [mu]g/m\3\, well below the 
corresponding annual NAAQS of 15.0 [mu]g/m\3\.
    As discussed above for PM-10, the changes to wintertime gasoline 
properties due to the relaxed Low RVP Rule and suspended County CBG 
Rule could result in increases in PM-10 emissions from vehicular 
exhaust. All of the PM-10 from vehicular exhaust can be assumed also to 
be fine particulate matter (i.e., PM-2.5), and thus the changes to the 
wintertime gasoline properties could also result in increased PM-2.5 
emissions from vehicular exhaust. However, we have no reason to believe 
that this hypothetical increase would be large enough to cause an 
exceedance of the 24-hour or annual PM-2.5 NAAQS. Therefore, we 
conclude that the changes in wintertime gasoline properties, expected 
to occur with the relaxation of the Low RVP Rule and the suspension of 
the CBG Rule, would not interfere with attainment or maintenance of the 
PM-2.5 NAAQS in Clark County.
    Based on our previous approvals of NAC section 590.065 (i.e., the 
Low RVP Rule) and the CBG Rule, and the nature of the regulatory 
changes submitted to us (e.g., relaxing a vapor pressure limit (not 
subject to preemption), updating specifications and test methods in the 
State rule, suspension of the county CBG rule) as well as the above 
evaluation of the impact of the changes in wintertime gasoline 
properties in Clark County on ambient CO, ozone, PM-10, and PM-2.5 
concentrations, we find that the changes would not interfere with 
attainment or maintenance of any of the NAAQS, nor would they interfere 
with any applicable requirement of the Act, and thus are approvable 
under CAA section 110(l). As such, we propose to approve the amendments 
to NAC section 590.065, and suspension of the CBG Rule, as submitted by 
NDEP on March 26, 2010, as revisions to the Nevada SIP.\23\
---------------------------------------------------------------------------

    \23\ In addition to gasoline vapor pressure requirements, NAC 
section 590.065 also includes maximum content limits in gasoline for 
lead, phosphorus, manganese, ethanol, and sulfur. See NAC section 
590.065(7). Because none of these content limits relate to gasoline 
vapor pressure requirements in Las Vegas Valley nor the CO emissions 
reductions achieved therefrom, and because the subsection in NAC 
section 590.065 containing these limits (i.e., subsection (7)) is 
severable from the rest of the rule, we are not including NAC 
section 590.065(7) in our proposed approval of amendments to NAC 
section 590.065.
---------------------------------------------------------------------------

VII. Proposed Action and Request for Comment

    Under section 110(k)(3) of the Act, EPA is proposing to approve 
NDEP's submittal dated September 18, 2008 of the Las Vegas Valley CO 
Maintenance Plan as a revision to the Nevada SIP because we find that 
it satisfies the requirements of section 175A of the CAA to include a 
reasonably accurate and comprehensive attainment inventory, an adequate 
maintenance demonstration, contingency provisions, and commitments to 
continue operation of an acceptable ambient monitoring network to 
verify continued attainment. Final approval of the Las Vegas Valley CO 
Maintenance Plan would make Federally enforceable the commitments, such 
as the commitment to continue operation of an adequate CO monitoring 
network, and the contingency provisions, contained therein. In 
addition, we are proposing to approve for transportation conformity 
purposes the motor vehicle emissions budgets in the Las Vegas Valley CO 
Maintenance Plan for years 2008, 2010, and 2020 because we find they 
meet the criteria found in 40 CFR 93.118(e). The budgets for 2008, 2010 
and 2020 are 658 tons per day, 686 tons per day, and 704 tons per day, 
respectively (based on typical weekday during the winter).
    Based in part on our proposed approval of the Las Vegas Valley CO 
Maintenance Plan, we are also proposing to approve NDEP's September 18, 
2008 request to redesignate Las Vegas Valley to attainment for the CO 
NAAQS. In doing so, we find that the area has met all of the criteria 
for redesignation under CAA section 107(d)(3)(E), i.e., the area has 
attained the CO standard; EPA has fully approved the Las Vegas Valley 
SIP for all requirements under section 110 and part D of the CAA that 
are applicable for purposes of redesignation; the improvement in CO 
conditions in Las Vegas Valley is due to permanent and enforceable 
reductions; and as described above, the State has submitted a 
maintenance plan for the area that meets the requirements of section 
175A.
    Contingency provisions in maintenance plans must include the 
measures contained in the SIP prior to redesignation, and for one such 
contingency measure included in the Las Vegas Valley CO Maintenance 
Plans, the State's Low RVP Rule, the responsible State agency (State 
Department of Agriculture) has not yet made the necessary commitment. 
Thus, our proposed approval of the Maintenance Plan and redesignation 
request is contingent upon submittal (and approval by EPA) of such a 
commitment as a revision to the Nevada SIP.\24\
---------------------------------------------------------------------------

    \24\ On July 12, 2010, the Nevada Department of Agriculture 
initiated a 30-day comment period to solicit comment (or request a 
public hearing) on the draft commitment regarding implementation of 
the contingency measure in the Maintenance Plan related to 
reinstatement of the Low RVP Rule. The Department's notice of intent 
to solicit public comment, which includes the commitment language, 
has been placed in the docket for this rulemaking. We have reviewed 
the language of the Department's draft commitment and expect to 
approve it if it is ultimately submitted to us without significant 
modification.
---------------------------------------------------------------------------

    We are also proposing to approve, under section 110(k)(3) of the 
CAA, NDEP's March 26, 2010 submittal of the

[[Page 44753]]

suspension of Clark County's Air Quality Regulations (AQR) Section 54 
(``Cleaner Burning Gasoline: Wintertime Program'') (``CBG 
Regulation''), and the amendments to the NAC section 590.065, including 
the relaxation in the State's wintertime gasoline RVP requirement for 
Clark County from 9.0 to 13.5 psi, because we find that doing so would 
not interfere with attainment or maintenance of any of the NAAQS or any 
applicable requirement of the Clean Air Act for the purposes of CAA 
section 110(l). We are not including subsection (7) of amended NAC 
section 590.065 in our proposed approval because the limits in 
subsection (7) of the amended rule are unrelated to the vapor pressure 
requirement and associated CO emissions reductions, and are severable 
from the rest of the rule.
    We will accept comments from the public on this proposal for the 
next 30 days.

VIII. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan under section 107(d)(3)(E) 
are actions that affect the status of a geographical area and do not 
impose any additional regulatory requirements on sources beyond those 
imposed by State law. A redesignation to attainment does not in and of 
itself create any new requirements, but rather results in the 
applicability of requirements contained in the CAA for areas that have 
been redesignated to attainment. Moreover, the Administrator is 
required to approve a SIP submission that complies with the provisions 
of the Act and applicable Federal regulations. 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, these actions merely propose to approve a 
State plan and redesignation request as meeting Federal requirements 
and do not impose additional requirements beyond those imposed by State 
law. For these reasons, these actions:
     Are not ``significant regulatory actions'' subject to 
review by the Office of Management and Budget under Executive Order 
12866 (58 FR 51735, October 4, 1993);
     Do not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Are certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Do not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Do not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Are not an economically significant regulatory action 
based on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Are not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Are not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Do not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).

In addition, 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. Nonetheless, EPA has 
discussed the proposed action with the one Tribe, the Las Vegas Paiute 
Tribe, located within Las Vegas Valley.

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Intergovernmental relations, Reporting and recordkeeping requirements.

40 CFR Part 81

    Environmental protection, Air pollution control, Carbon monoxide, 
National parks, Wilderness areas.

    Dated: July 21, 2010.
Keith Takata,
Acting Regional Administrator, Region IX.
[FR Doc. 2010-18645 Filed 7-28-10; 8:45 am]
BILLING CODE 6560-50-P