44734 Federal Register / Vol. 75, No. 145 / Thursday, July 29, 2010 / Proposed Rules 

considered as contributing to 

nonattainment in Denver. 

With respect to the 1997 8-hour ozone 

standards, we believe that the 

submission adequately establishes that 

sources in Albuquerque/Bernalillo 

County are not significantly 

contributing to violations of that 

NAAQS in any other state. As noted 

previously, EPA will be acting on the 

other elements of Section 110(a)(2)(D)(i) 

in separate rulemakings. 

V. Proposed Action 

We are proposing to approve a 

revision to the New Mexico SIP which 

adequately demonstrates that air 

pollutant emissions from sources within 

Albuquerque/Bernalillo County do not 

significantly contribute to 

nonattainment of the relevant NAAQS 

on any other state. 

Information provided by New Mexico 

Environment Department and AQCB in 

the technical demonstration sufficiently 

demonstrates that emissions from 

Albuquerque/Bernalillo County do not 

significantly contribute to downwind 

nonattainment. Thus, EPA concludes 

that the New Mexico SIP as it pertains 

to Albuquerque/Bernalillo County 

complies with CAA section 

110(a)(2)(D)(i)(I). 

VI. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

Federal regulations. 42 U.S.C. 7410(k); 

40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, EPA’s role is to approve 

state choices, provided that they meet 

the criteria of the Clean Air Act. 

Accordingly, this action merely 

approves state law as meeting Federal 

requirements and does not impose 

additional requirements beyond those 

imposed by state law. For that reason, 

this action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Order 12866 (58 FR 51735, 

October 4, 1993); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this rule does not have 

tribal implications as specified by 

Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the state, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Intergovernmental 

relations, Ozone, Particulate matter, 

Reporting and recordkeeping 

requirements, Volatile organic 

compounds. 

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

Dated: July 20, 2010. 

Lawrence E. Starfield, 

Acting Regional Administrator, Region 6. 

[FR Doc. 2010–18560 Filed 7–28–10; 8:45 am] 

BILLING CODE 6560–50–P 

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 

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1Specifically, 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. 

2The 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’’). 

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: 

Plan or Rule Adoption date(s) State of Nevada 

submittal date(s) 

Carbon Monoxide Redesignation Request and 

Maintenance Plan, Las Vegas Valley Nonattainment Area, Clark County, Nevada (September 2008).

Adopted by the Clark County Board of Commissioners on September 2, 2008.Submitted by NDEP by letter dated September 18, 2008. 

Clark County Air Quality Regulations, Section 

54 (‘‘Cleaner Burning Gasoline (CBG): Wintertime Program’’) (Suspended).

Adopted by the Clark County Board of Commissioners on September 15, 2009, effective September 29, 2010.Submitted by NDEP by letter dated March 26, 

2010. 

Nevada Administrative Code (NAC) section 

590.065 (amended).

Adopted by the Nevada Board of Agriculture 

on December 9, 2010, effective January 28, 

2010.

Submitted by NDEP by letter dated March 26, 

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, 

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3We 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. 

4On 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. 

5Thus, 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. 

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. 

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

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

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). 

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 thenapplicable 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. 

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6While 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. 

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

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 EPAapproved 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. 

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7EPA 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. 

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, eighthour 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. 

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, qualityassured monitoring data that are 

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8The 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. 

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 

Monitoring site name 

2nd highest 8-hour concentration (ppm) 2nd highest 1-hour concentration (ppm) 

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 EPAapproved 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

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 

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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. 

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

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 

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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 TCMrelated 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 

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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. 

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10For 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 ozonespecific 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. 

11See tables 3–2 and 3–12 from the 2005 CO Plan 

for estimates of population, VMT, and area-wide CO 

emissions. 

12The 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. 

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. 

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 onroad 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

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 

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13The 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. 

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. 

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 EPAapproved 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

• 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 

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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. 

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14The 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. 

TABLE 3—LAS VEGAS VALLEY CO 

MAINTENANCE PLAN AREA-WIDE

MODELING RESULTS

[Peak 8-hour UAM concentrations] 

Year Concentration 

(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 microscale 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 microscale 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 microscale 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] 

Intersection 

Year 

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. 

To identify a safety margin consistent 

with maintenance of the CO standard 

through the initial maintenance period, 

the maintenance plan scaled up the onroad 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 

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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 

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15On 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. 

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

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. 

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16The 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. 

17The 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.’’ 

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

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. 

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 

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18The 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. 

19While 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. 

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. 

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). 

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 

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20The 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). 

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. 

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 μg/m3) 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, 

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44752 Federal Register / Vol. 75, No. 145 / Thursday, July 29, 2010 / Proposed Rules 

21The PM–10 NAAQS is 150 micrograms per 

cubic meter (μg/m3), 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 μg/m3, as determined in 

accordance with appendix K to 40 CFR part 50, is 

equal to or less than one. See 40 CFR 50.6. 

22An 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. 

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. 

24On 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. 

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

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 μg/m3, well 

below the corresponding 24-hour 

NAAQS of 35 μg/m3. The highest 

annual concentration, also recorded as 

the Sunrise Avenue site, is 10.3 μg/m3, 

well below the corresponding annual 

NAAQS of 15.0 μg/m3. 

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

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

We are also proposing to approve, 

under section 110(k)(3) of the CAA, 

NDEP’s March 26, 2010 submittal of the 

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Federal Register / Vol. 75, No. 145 / Thursday, July 29, 2010 / Proposed Rules 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 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

50 CFR Part 622 

RIN 0648–AY10 

Fisheries of the Caribbean, Gulf of 

Mexico, and South Atlantic; SnapperGrouper Fishery off the Southern 

Atlantic States; Amendment 17A 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice of Availability of 

Amendment 17A to South Atlantic 

Snapper-Grouper Fishery Management 

Plan; request for comments. 

SUMMARY: The South Atlantic Fishery 

Management Council (Council) has 

submitted Amendment 17A to the 

Fishery Management Plan for the 

Snapper-Grouper Fishery of the South 

Atlantic Region (FMP) for review, 

approval, and implementation by 

NMFS. The amendment proposes to 

establish a rebuilding plan for red 

snapper, specify a proxy for the fishing 

mortality rate that will produce the 

maximum sustainable yield (MSY), 

specify the optimum yield (OY), specify 

the value for the minimum stock size 

threshold (MSST), and specify an 

annual catch limit (ACL) and 

accountability measures (AMs) for red 

snapper. Amendment 17A would also 

prohibit harvest and possession of red 

snapper in or from Federal waters of the 

South Atlantic and in or from state 

waters for vessels holding a Federal 

snapper-grouper permit, and implement 

an area closure that extends from 

southern Georgia to northern Florida 

where all harvest and possession of 

snapper-grouper would be prohibited 

(except when fishing with black sea bass 

pots or spearfishing gear for species 

other than red snapper). Additionally, 

Amendment 17A would require the use 

of non-stainless steel circle hooks north 

of 28° N. lat. and require a monitoring 

program for South Atlantic red snapper. 

The actions contained in Amendment 

17A are intended to end overfishing of 

South Atlantic red snapper and rebuild 

the fishery. 

DATES: Comments must be received no 

later than 5 p.m., eastern time, on 

September 27, 2010. 

ADDRESSES: You may submit comments, 

identified by ‘‘0648–AY10’’, by any one 

of the following methods: 

• Electronic Submissions: Submit all 

electronic public comments via the 

WReier-Aviles on DSKGBLS3C1PROD with PROPOSALS