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Citation: 69 Fed. Reg. 60328 2004

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of$10,125. Such fee is not required when, in connection with the change soughtunder this paragraph, a petition is filed for the establishment ofnew tolerances totake the place ofthose soughtto be revoked and a fee ispaid

asrequired byparagraph (a) ofthis section.



### (1) * * * A fee of $2,025 shall accompany every request for awaiver or refund, as specified in paragraph (in) of this section, except that the fee under this paragraph shall notbe imposed on any person who has no financial interest in any action requested by such person under paragraphs (a)through (j) ofthis section. * * *

33. Section 180.40 is amendedby revising the last sentence in paragraph (f)toread as follows: 

### §180.40 Tolerances forcrop groups.

(f) * * * Processing data will be required prior to establishment of a group tolerance, and tolerances will not be granted on a group basis as to processed foods prepared from crops covered by the group tolerance.

34. Section 180.1229 is added to subpart D to read as follows: §180.1229 Benzaldehyde; exemption from
the requirement of atolerance.

An exemption from the requirement ofa tolerance is established for residues ofbenzaldehyde when used as a bee repellant in the harvesting ofhoney. 35. Section 180.1230 is added to subpart D to read as follows: 

### §180.1230 Ferrous sulfate;exemption from the requirement ofatolerance.

An exemption from the requirement ofa tolerance is established for residues offerrous sulfate.

36. Section 180.1231 is added to subpart D to read as follows:
§180.1231 Lime; exemption from the requirement ofatolerance.

An exemption from the requirement ofa tolerance is established for residues oflime.

37. Section 180.1232 is added to subpart D to read as follows:
§180.1232 Lime-sulfur; exemption from the requirement of atolerance.

An exemption from the requirement ofa tolerance is established for residues oflime-sulfur.

38. Section 180.1233 is added to subpart D to read as follows: 

### §180.1233 Potassium sorbate; exemption from the requirement ofatolerance.

An exemption from the requirement ofa tolerance is established for residues ofpotassium sorbate.

39. Section 180.1234 is addedto subpart D to read as follows:
§180.1234 Sodium carbonate; exemption from the requirement ofatolerance.

An exemption from the requirement ofa tolerance is established for residues ofsodium carbonate.

40. Section 180.1235 is addedto subpart D to read as follows:
§180.1235 Sodium hypochlorite; exemption from the requirement ofa tolerance.

An exemption from the requirement ofa tolerance is established for residues ofsodium hypochlorite.

41. Section 180.1236 is addedto subpart D to read as follows: 

### §180.1236 Sulfur;exemption from the requirement of atolerance.

An exemption from the requirement ofa tolerance is established for residues ofsulfur.

42. Section 180.1237 is addedto subpart D to read as follows:
§180.1237 Sodium metasilicate; exemption from the requirement ofa tolerance.

An exemption from the requirement ofa tolerance is established for residues ofsodium metasilicate when used as plant desiccants, so long as the metasilicate does not exceed 4% by weight in aqueous solution.

43. Section 180.1238 is addedto subpart D to read as follows:
§180.1238 Oilof lemon; exemption from the requirement of atolerance.

An exemption from the requirement ofa tolerance is established for residues ofoil oflemon when used as a postharvest fungicide.

44. Section 180.1239 is addedto subpart D to read as follows: 

### §180.1239 Oilof orange; exemption from the requirement of atolerance.

An exemption from the requirement ofa tolerance is established for residues ofoil oforange when used asa postharvest fungicide.
[FR Doc. 04-22584 Filed 10-7-04; 8:45 am]

BILLING CODE 6560-50-S ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 52 and 81 [AZ104-0069; FRL-7823-6]
Approval and Promulgation of Implementation Plans and Designation of Areas forAir Quality Planning Purposes; Arizona

AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule.

SUMMARY: EPA isproposing to approve the Maricopa Association of Governments (MAG) serious area carbon monoxide (CO) state implementation plan (SIP) for the Maricopa County CO nonattainment area (the metropolitan Phoenix area, Arizona) as meeting the Clean Air Act (CAA)requirements for serious CO nonattainment areas. We are also proposingto approve the MAG CO redesignation request and maintenance planfor the Maricopa County CO nonattainment area as meeting CAA requirements for redesignation requests and maintenance plans. In addition, we
are proposing to make aboundary change under Section 107 ofthe CAA to take the Gila River Indian Community (GRIC) out ofthe Maricopa County maintenance area. The portion ofthe Gila River Indian Community which is currently in the Maricopa County CO nonattainment area will be "unclassifiable/attainment" for CO, and will notbe subject tothe MAG CO Redesignation Request and Maintenance Plan. DATES: Written comments must be received at the address below on or before November 8, 2004. ADDRESSES: Formal written comments shouldbe mailed or emailed toWienke Tax, Office ofAir Planning (AIR-2), U.S. Environmental Protection Agency, Region 9, 75 Hawthorne Street, San Francisco, CA 94105-3901, tax.wienke@epa.gov.Comments may alsobe submitted through the Federal Register Web site at http:// www.regulations.gov.Weprefer electronic comments.

You can inspect copies ofEPA's Federal Register document and technical support documents (TSD) at

our Region 9 office during normal business hours (see address above). Due
to increased security, we suggest that you call at least 24 hours prior to visiting the Regional Office so thatwe

can make arrangements to have

someone meet you.The Federal Register document and TSD are also available as electronic files onEPA's 

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Region 9 Web Page at http:// www.epa.gov/region09/air.

You may inspect and copy the rulemaking docket for this notice at the following location during business hours.

Environmental Protection Agency, Region 9,AirDivision, AirPlanning Office (AIR-2), 75 Hawthorne Street, SanFrancisco, CA 94105.

Copies ofthe SIP materials are also available for inspection at the address listed below:

Arizona Department ofEnvironmental Quality, 1110 W. Washington Street, First Floor, Phoenix, AZ 85007, Phone: (602) 771-4335.

FOR FURTHER INFORMATION CONTACT: Wienke Tax, Office ofAir Planning, U.S. Environmental Protection Agency, Region 9, (520) 622-1622, e-mail: tax.wienke@epa.gov,orhttp:// www.epa.gov/region09/air.

SUPPLEMENTARY INFORMATION: Throughout this document, the terms "we," "us," and "our" mean U.S. EPA.

Table ofContents
I. Summary of Today's ProposedAction II.The Serious Area CO SIPfor thePhoenix Area III. The CAA's Requirements for Serious CO Nonattainment AreaPlans IV. The Revised 1999 COPlan's Compliance With the CAA'sRequirements for Serious CO Nonattainment Area Plans A. Completeness ofthe SIP Submittals and

Adequacy ofthe Motor Vehicle Emissions Budget B.Emissions Inventory C.Adequate Monitoring Network D.Implementation ofReasonably Available

Control Measures E. Demonstration ofAttainment F. Reasonable Further Progress G. VMTTracking and Reporting H. Transportation Control Measures To

Offset Growth in Emissions I.Contingency Measures J.Enhanced I/MProgram K. Wintertime Oxygenated Gasoline

Program L.General SIPRequirements V. The CAA's Requirements for Serious CO Maintenance Plans and Redesignation Requests VI. The MAGCO Redesignation Request and Maintenance Plan's Compliance With the CAA's Requirements forCO Redesignation Requests and Maintenance Plans A. General SIPRequirements B.Attainment ofthe CO NAAQS C.Meeting Applicable Requirements of

Section 110 and PartD D.Fully-Approved SIPUnder Section

110(k) ofthe CAA (NSR) E. Improvement in Air Quality Due to

Permanent andEnforceable Measures F. Fully-Approved Maintenance Plan

Under Section 175A VII. EPA's Evaluation ofthe Transportation Conformity Requirements in the MAG CO Redesignation Request and Maintenance Plan VIII. GRIC Boundary Change Under CAA Section 107 A. Background B. EPA Review ofthe Community's

Request C. Redesignation ofthe Northern Portion of

the Reservation IX. Proposed Action X. Statutory andExecutive Order Reviews
I. Summary ofToday's Proposed Action

We are proposing to approve the MAG serious area SIP for attainment ofthe CO air quality standard in the metropolitan Phoenix (Maricopa County), Arizona

area. This action is based on our determination that this SIP complies with the CAA's requirements for attaining the CO standard in serious CO nonattainment areas such as the metropolitan Phoenix area.

We are alsoproposing to approve the MAG CO redesignation request and maintenance plan for the Maricopa County CO nonattainment area as meeting CAArequirements for redesignation requests andmaintenance plans.

We are alsoproposing to make a boundary correction under Section 107 ofthe CAA for the Gila River Indian Community.

II. The Serious Area COSIP forthe Phoenix Area

We are proposing to approve the RevisedMAG 1999Serious Area Carbon MonoxidePlan fortheMaricopaCounty
NonattainmentArea,March 2001. The plan was developed by MAG, the lead air quality planning agency in Maricopa County. The Arizona Department of Environmental Quality (ADEQ submitted this plan as arevision to the Arizona SIP onMarch 30, 2001 and EPA received it onApril 2, 2001. We refer to this plan in this document asthe Revised CO Plan or the Revised 1999 CO plan, orvariations ofthese.

As submitted, the Revised 1999 CO plan consists ofthe mainplan document, three volumes oftechnical appendices and three volumes of commitments fromvarious agencies to implement CO controls. The plan contains 1993 and 1996 emission inventories, a reasonably available control measures (RACM) analysis, vehicle miles traveled (VMT) tracking procedures, annual VMT projections through 2000, and contingency

measures. Ituses the Urban Airshed Model (UAM) and CAL3QHC microscale model tomodel air quality in 1994 as a base year and in 2000 as the attainment year and demonstrates both reasonable further progress towards and attainment ofthe CO standard by December 31, 2000.

The MAGplan shows thatthe principal sources contributing to CO exceedances are gasoline on-road motor vehicles, gasoline non-road engines, and woodburning. MAG plan, p. ES-1.

In earlier actions, we have already approved revisions to Arizona's Cleaner Burning Gasoline (CBG) program and to Arizona's Vehicle Emissions Inspection (VEI) Program as well as the Maricopa County Woodburning curtailment program. 69 FR 10161 (March 4, 2004), 68 FR 2912 (January 22, 2003), 64 FR 60678 (November 8, 1999) and 67 FR 48718 (July 25, 2002). The revisions to these programs are the principal controls relied on in the revised MAG CO plan to demonstrate attainment. We have alsopreviously approved the commitments by the Phoenix area cities and towns to adopt and/orimplement CO control measures. We approved these commitments aspart ofthe serious area PM-10 plan approval on July 25, 2002 at 67 FR48718. See 40 CFR 52.120(c)(100). Many ofthese commitments by Phoenix area cites and
towns commit to measures which address CO as well as PM-10 emissions reductions.

For a complete history ofthe CO planning efforts in the Phoenix area as well as the history ofthe development ofthe CO plan,please see Section 1in EPA'sTSD.

III.The CAA's Requirements for Serious CO Nonattainment AreaPlans

The Phoenix area was reclassified frommoderate to serious for CO onJuly 29, 1996 (61FR 39343) because the area had not attainedthe CO standard bythe moderate area deadline ofDecember 31, 1995. As a result ofthis reclassification, Arizona was required to submitby February 28, 1998, a revision to its SIP for the Phoenix area that met the CAA requirements for serious CO nonattainment areas found in section 187(a) and section 172(c)(1). This SIP revision needed to show attainment of the CO standard byDecember 31, 2000. In summary, these requirements are:

(a) Implementation of allreasonably available control measures (RACM), including reasonably available control technology (RACT) for stationary

sources (CAA section 172(c)(1));

(b)Provisions for attainment, and a demonstration thatthe plan will provide for attainment by no laterthan December 31, 2000 (CAA section 187(b)(7));

(c) Provisions for such specific annual emission reductions as are necessary to attainby December 31, 2000 (CAA sections 172(c)(2) and 187(b)(7)); 60329

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(d)Forecasts ofvehicle miles traveled (VMT) in the nonattainment area for eachyear before the year in which the plan projects attainment (CAA section 187(a)(2)(A));

(e) An enhanced vehicle inspection and maintenance program (CAAsection 187(a)(6));

(f)An oxygenated gasoline program (CAA sections 187(b)(3) and 211(m));

(g)Transportation control strategies and measures to offset any growth in emissions fromvehicle miles traveled or numbers ofvehicle trips (CAA section 187(b)(2));

(h)Contingency measures that will be implemented ifthe area fails to attainby its applicable deadline, fails to make reasonable further progress, or vehicle mile traveled estimates exceed those forecasted (CAA sections 172(c)(9) and 187(a)(3));

(i) Acomprehensive, accurate, current inventory ofactual emissions from all

sources ofCO (CAA sections 172(c)(3) and 187(a)(5)); and

(j)A transportation conformity budget (CAA section 176(c)).

Serious area CO SIPs must also meet the general requirements applicable to all SIPs including reasonable notice and public hearing under section 110(a), necessary assurances thatthe implementing agencies have adequate personnel, funding and authority under section 110(a)(2)(E)(i) and 40 CFR 51.280; and the description of enforcement methods asrequired by40 CFR 51.111.1

We have issued a General Preamble 2 describing ourpreliminary views on how the Agency intends to review SIPs submitted to meet the Clean Air Act's requirements for CO SIPs. We have also issued other guidance documents related to CO SIPs or provisions ofthose SIPs, including the "Technical Support Document to Aid States with the Development ofCarbon Monoxide State Implementation Plans," Office ofAir Quality Planning and Standards (OAQPS), U.S. EPA, EPA-452/R-92- 003 (July 1992).

On July 8, 1999, ADEQ submitted the
MAG 1999SeriousArea COPlan("1999 CO Plan") to EPA. We found the submittal complete on September 9, 1999. The 1999 CO Plan was revised because the Arizona legislature passed

'Serious area SIPs must alsoinclude new source review (NSR) permitting rules that meetthe requirements ofsections 172(c)(5) and 173. In practice, NSR rules are submitted and reviewed separately from the rest ofthe serious area CO plan. Maricopa County has submitted a complete NSR rule.

2"State Implementation Plans; General Preamble
for the Implementation of Title I ofthe Clean Air Act Amendments of 1990," 57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28, 1992). House Bill (HB) 2104 during the 2000 regular session, which repealed the
remote sensing portion ofthe VEI
program. We indicated that the 1999 CO Plan would need to be revised toreflect the change in the VEIprogram. MAG conducted new air quality modeling and revised the 1999 CO Plan. On April 2, 2001, ADEQ submitted the Revised 1999 MAG Serious Area COPlan("Revised 1999 CO Plan") to EPA.

IV. The Revised 1999 COPlan's Compliance WiththeCAA's Requirements for Serious CO Nonattainment Area Plans

The following sections present a summary ofour evaluation ofthe Revised 1999 CO Plan's compliance with the applicable CAArequirements for serious area SIPs for CO. Our complete evaluation isfound in the EPA TSD for this action.3A copy ofthe EPA TSD can be obtained by calling or writing the contact person listed above.

A. CompletenessoftheSIPSubmittals andAdequacyoftheMotorVehicle EmissionsBudget

The first step we take afterreceiving

a SIP submittal is to determine ifit is complete. CAA section 110(k)(1)(B) requires that we review all SIPs and SIP revisions for completeness within 60 days ofreceipt. The completeness review allows us to quickly determine if the submittal includes allthe necessary items and information we need totake action onit.We make completeness determinations using criteria we have established in 40 CFR part 51, Appendix V.We found ADEQ's March 30, 2001 submittal (received onApril 2, 2001) of the Revised 1999 CO Plan complete and notified the State on October 9, 2001. See Letter, Jack P. Broadbent, EPA, to Jacqueline Schafer, ADEQ. Our completeness determination is documented in Section 2 ofthe EPA TSD. Section 176(c) ofthe Clean Air Act requires that federally funded or approved transportation plans,
programs, and projects in nonattainment

areas "conform" tothe area's air quality SIPs. Conformity ensures that federal transportation actions donot worsen an area's air quality orinterfere with its meeting the air quality standards. We have issued a conformity rule that establishes the criteria andprocedures for determining whether or not transportation plans, programs, and

3See "Technical Support Document forthe Notice ofProposed Rulemaking on the Carbon Monoxide Serious Area Planning Requirements for the Maricopa County, Arizona Nonattainment Area," June 2004, AirDivision, USEPA Region 9. projects conform. See 40 CFRpart 93, subpart A.

One ofthe primary tests for conformity is to show that transportation plans and improvement programs will not cause motor vehicle emissions to increase above levels needed to make progress toward andto meet the air quality standards. The
motorvehicle emissions levels needed
to make progress toward and to meet the air quality standards are set forth in the area's air quality SIPs as an "emissions budget for motor vehicles." The conformity rule's requirements and EPA'spolicy on emissions budgets are foundin the preamble tothe November 24, 1993 transportation conformity rule (58 FR 62193-96), in the sections ofthe rule referenced above, andin subsequent revisions to the conformity rule (69 FR 40004, July 1,2004).

Before an emissions budget in a submitted SIP revision may be used in

a conformity determination, we must first determine that it is adequate. The criteria by which we determine adequacy of submitted emission budgets

are outlined in conformity rules in 40 CFR 93.118(e)(4).

The Revised 1999 CO Plan, submitted

on March 30, 2001, established arevised mobile source emissions budget of412.2 metric tons per day (mtpd). Revised 1999 CO Plan, p. 9-11. Wefound this budget adequate for transportation conformity purposes on September 28, 2001. See letter,JackBroadbent, EPA Region 9 toJacqueline Schafer, ADEQ, andJames Bourey, MAG. Our finding

was published in the Federal Register

on October 17, 2001 (66FR 52761) and became effective 15 days later on November 1, 2001.

B.EmissionsInventory

CAA section 172(c)(3) requires all serious area CO SIP submittals to include a comprehensive, accurate, and
current inventory ofactual emissions from all sources in the base year inventory to forecast and backcast other years. Maricopa County chose the year 1993 as thebase year for its serious area CO SIP since itwas the most complete emission inventory available at the time MAG started its modeling forthe 1999 CO Plan.MAG developed a 1994 modeling inventory based onthe 1993 annual CO inventory. The base year and forecasted 1996 emission inventories described all the sources ofCO for the nonattainment area. In 1998, Maricopa County completed the draft 1996 CO emissions inventory. In response to public comments onthe Draft MAG 1998 CO Plan, a comparison ofthe 1993 and 1996 periodic inventories and an evaluation ofthe 1994 base case 60330

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modeling inventory were conducted. MAG subsequently revised the nonroad equipment modeling assumptions tobe

more consistent with the 1996 CO inventory. The comparison concluded that the 1994 modeling inventory contained the most recent and valid assumptions.

The emission inventory is divided into source categories and subcategories. The main source categories are stationary sources (bothpoint and aggregated), area sources, on-road mobile sources, and off-road mobile

sources. Source categories provide a convenient way to organize the emission inventory and to determine the significance ofparticular sources. Seasonal inventories are provided to account for the differences in emissions occurring during the times ofyear when Maricopa County used to exceed the 8- hour CO standard. We are approving the emission inventories ofthe Maricopa County CO nonattainment area as meeting therequirements of section 172(c)(3) ofthe CAA.

On September 18, 1996, we proposed approval ofthe 1990base year CO emissions inventory for Maricopa County (see 61 FR 49087). When we finalize today's proposed action, we will also finalize approval ofthe 1990 base year emissions inventory proposed on September 18, 1996.

C.AdequateMonitoringNetwork

The CAArequires states to establish and operate air monitoring networks to compile data onambient air quality for all criteria pollutants. Section 110(a)(2)(B)(i). Our regulations in 40 CFR part 58 establish specific regulatory requirements for operating air quality surveillance networks tomeasure ambient concentrations ofCO, including
measurement method requirements, network design, quality assurance procedures, and in the case oflarge urban areas, the minimum number of monitoring sites designated as National Air Monitoring Stations (NAMS).

Ambient networks, however, do not need tomeet all our regulations tobe found adequate to support air quality modeling. A good spatial distribution of sites, correct siting, and quality-assured and quality-controlled data are the most important factors for air quality modeling. Nonattainment area plans developed under title I,part D ofthe Clean Air Act are not generally required
to address howthe area's air quality network meets our monitoring regulations. These plans are submitted
too infrequently to serve as the vehicle for assuringthat monitoring networks remain current. For this action, we are discussing the adequacy ofthe Phoenix area monitoring network solelyto support

our finding that the Revised 1999 CO Plan appropriately evaluates the CO problem in the Phoenix area. Reliable ambient datais necessary to validate the base year air quality modeling which in
turn is necessary to assure a sound attainment demonstration.

There are fourteen CO monitoring sites in the metropolitan Phoenix area; thirteen are operated bythe Maricopa County Environmental Services Department and one byADEQ. Figure 4-3 on page 4-7 in the Revised 1999 CO Plan lists the names ofthe sites and their locations in the Phoenix area. These sites all use EPAreference methods, are sited according to our regulations, meet the applicable monitoring objections in our regulations, and are operated according
to ourregulations. We therefore find that the monitoring network operated by the MCESD andADEQ is adequate to support the technical evaluation ofCO nonattainment problem in the Revised 1999 CO Plan. See also EPA TSD section "Ambient Air Quality Surveillance".

D.Implementationof Reasonably Available ControlMeasures

CAA section 172(c)(1) requires that nonattainment plans provide for the implementation of allreasonably available control measures (RACM) as expeditiously aspracticable. We interpret this requirement to require a state to consider available measures for controlling CO and to adopt and implement those measures that are reasonably available for implementation in the area as components ofthe area's attainment demonstration. In general,

we do not consider a measure tobe reasonably available ifit is economically ortechnologically infeasible for the area, would not advance attainment ofthe relevant standard in the area, oris absurd, unenforceable orimpracticable. General Preamble at 13560.

As described above, the principal

sources ofCO in the metropolitan Phoenix area are (in order of importance) on-road motor vehicles, non-road engines, and residential woodburning, which collectively
account for 99 percent ofthe 1996 seasonal inventory. Revised 1999 CO Plan, Figure ES-2. The Revised 1999 CO Plan evaluates abroad range ofcontrols for each ofthese sources categories. See Revised 1999 CO Plan, Chapter 6.

For on-road motor vehicles, adopted controls include the State's enhanced vehicle emission inspection program, cleaner burning gasoline program including a 3.5 percent oxygen content and 9 psi volatility standard, requirements andincentives for the use ofalternative fueled vehicles, and

numerous transportation control

measures (TCMs). See Revised 1999 CO Plan, Chapter 8. We find thatthese

measures along with the federal motor vehicle tailpipe standards provide a comprehensive control strategy for attaining the CO standard and provide for the implementation ofRACM in the on-road motor vehicle category as required by CAA section 172(c)(1). See EPATSD section "Implementation of RACM for On-Road Motor Vehicle Controls-Technology."

CAA section 187(b)(2) requires a State with a serious CO nonattainment area to consider the TCMs in section 108(f) and choose to implement suchmeasures as necessary to demonstrate attainment. The Phoenix area has a longhistory of adopting TCMs, including those in section 108(f), for controlling CO. The Revised 1999 CO Planimplements the section 108(f)TCMs and includes additional measures in support ofthe attainment demonstration. SeeRevised 1999 CO Plan, Table 7-2 and Chapter 8. Wetherefore find that the Revised 1999 CO Plan complies with CAA section 187(b)(2) and 172(c)(1). See EPATSD section "Implementation ofRACM for On-Road Motor Vehicle ControlsTransportation Control Measures."

The nonroad (mobile) engine category

covers a diverse collection ofengines, equipment and vehicles fueled by gasoline, diesel, and other fuels and includes outdoor power equipment, recreational equipment, farm equipment, construction equipment, lawn and garden equipment, aircraft, locomotives, and marine vessels. Although diesel engines dominate the market fornonroad engines, ninety percent ofCO emissions fromthe nonroad category come from gasolinepowered nonroad engines.

Starting in the mid-1990s, EPA promulgated national emission standards for a broad range ofnonroad engines. SeeEPA TSD section "Implementation ofRACM for Nonroad Engines." Nonroad engines soldin Arizona are required to comply with these national standards which constitutes a RACM-level program for controlling emissions from nonroad engines.

In addition, Arizona's CBGprogram regulates gasoline used in nonroad engines. The Revised 1999 CO Plan also includes anumber ofothernonroad engine measures. SeeEPATSD section "Implementation ofRACM for Nonroad Engines." With the national emission standards and the additional State 

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measures, we find thatthe Revised 1999 CO Plan provides for the implementation ofRACM for nonroad engines.

The residential wood combustion (RWC) category includes emissions from the burning of solidfuel in residential fireplaces and woodstoves as well as barbecues and fire pits. Measures to control CO from residential woodburning include apublic education program, woodburning curtailment programs, retrofit requirements and restrictions or bans on the installation ofwoodburning stoves and/or fireplaces.

The Maricopa County Environmental Services Department's Rule 318, Approval ofResidential Woodburning Devices, establishes standards for the approval ofresidential woodburning devices that can be used during restricted-burn periods. Maricopa County's Residential Woodburning Restriction Ordinance provides that restricted-burn periods are declared by the Control Officer when the Control Officer determines that air pollution levels could exceed the CO standard and/orthe PM standard (150 gg/m3). We approved Rule 318 and an earlier version ofthe ordinance (revised April 21, 1999) as providing for the implementation ofRACM. See 64 FR 60678 (November 8, 1999).

The Revised 1999 CO Plan includes a number ofother woodburning measures. We find thatthese measures along with Maricopa County's woodburning rules provide for the implementation of RACM for residential wood combustion. SeeEPA TSD section "Implementation ofRACM for Residential Wood Combustion."

E.Demonstrationof Attainment
CAA section 187(a)(7) requires serious

area plans to provide for attainment of the CO NAAQS by December 31, 2000 andto contain ademonstration thatthe plan will provide for attainment. Under

our guidance, an attainment demonstration maybe made using EPAapproved air quality models and must include the control strategy. General Preamble at 13533.

There are two parts to reviewing a modeled attainment demonstration: (1) Evaluating the technical adequacy ofthe modeling itself, and (2)evaluating the control measures that are relied on to demonstrate attainment. We discuss each partbelow.

1.Air Quality Modeling

MAG used the Urban Airshed Model (UAM), the standard model for carbon monoxide attainment demonstrations, consistent with EPA guidance, to predict the effect ofcontrolmeasures in its attainment demonstration. UAM requires meteorological inputs, such as temperature and wind speeds, as well as initial and boundary conditions for CO concentrations, and CO emissions. These must be allocated in time and
space; every hour ofthe simulation and every one square mile grid cell requires these inputs. Diagnostic testing is performed to ensure the model is performing well for achosen CO episode, which in this case was December 17, 1994, which at 10.5 ppm had the highest CO peak and most widespread high COreadings observed during 1994. Once the model predicts observed CO concentrations for this chosen CO episode adequately, postcontrol measure emissions are input to the model to project future air quality. Separate predictions are also made "hot spots", intersections with high traffic and congested conditions, using the CAL3QHC model. This "microscale" component is then combined with the UAM results. The total prediction is then compared tothe level ofthe NAAQS, 9.0 ppm, to demonstrate attainment.

As detailed in the TSD, MAG followed accepted procedures in developing the model inputs, performing diagnostic testing ofthe results, and showing adequate model performance. Model performance statistics met EPA-recommended goals. The observed spatial andtemporal patterns ofCO were replicated fairly well bythe model. While there were

some discrepancies, these were attributed to lack ofobservations at

some locations, and by slight shifts in wind patterns. Thatis, ifthe wind field input to the model hadbeen slightly different, some high CO locations in the model predictions would have better matched the monitor locations. But since the magnitude, spatial extent, and timing of elevated CO concentrations is very similar between the model and observations, EPA determines the model performed adequately for attainment demonstration purposes.

Overall, the modeling done byMAG
meets EPA guidelines and performs well enough to be relied upon asthe basis for the CO attainment demonstration. EPA therefore proposes to approve the CO attainment demonstration.

2.Control Measures Relied on for Attainment

For demonstrating attainment ofthe CO standard, the Revised 1999 CO Plan relies primarily on reductions from the VEI and CBG programs as well as much smaller reductions from three other
measures, traffic synchronization, intelligenttransportation systems, and deferring emissions associated with government activities. See Revised 1999 CO Plan,Figure 9-1. We have previously approved all ofthese

measures. See 68 FR 2912, 69 FR 10161, 64 FR 60678, and 67FR 48718.

As part ofthese approvals, we have evaluated each ofthese measures to

ensure thatthey meet our SIP enforceability criteria. These criteria

ensure thatthe measure's compliance requirements-applicability, performance standards, compliance schedule, and monitoring methods-are clear.

We have also evaluated the CO emissions reductions credited to each

measure in the attainment demonstration to ensure they are reasonable. We found thatthe emission reduction estimates for each source category are consistent with research on the applicable control methods and are appropriately applied in the attainment demonstrations. Finally, we have determined thatthe measures relied on for attainment are being expeditiously implemented. See EPA TSD, section "Attainment Demonstration".

F. ReasonableFurther Progress
CAA section 172(c)(2) requires nonattainment plans to provide for reasonable further progress (RFP), which is defined in section 171(1) as "such annual incremental reductions in emissions ofthe relevant air pollutant as

are required bythis part [part D oftitle I]or may reasonably be required by the Administrator forthe purpose of ensuring attainment ofthe applicable national ambient air quality standard by the applicable date." For serious CO nonattainment areas, CAA section 187(a)(7) alsorequires the plans to provide for such specific annual emission reductions as are necessary to attain the standard by the applicable attainment date.

We find thatthe Revised 1999 CO Planprovides for RFP andfor such specific annual emission reductions as

are necessary to attain the standard by the December 31, 2000 as required by the Act.4The Revised 1999 CO Plan includes an RFP demonstration for the years 1994, 1999, and 2000. 1994 is the base year, 1999 is the year before the
two largest measures in the Revised 1999 CO Plan (revisions to the VEI and CBGprograms) were implemented, and 2000 is the attainment year.Total design day CO emissions drop from 687 mtpd

4This finding is further supported by our finding that the area attained the CO standard by December 31, 2000. (68 FR 55008, effective November 21, 2003). 60332

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in 1994 to 686 mtpd in 1999 to 640 mtpd in 2000. Revised 1999 CO Plan, Figure 9-4. Total CO emissions drop
very little from 1994 to 1999 primarily because a large increase in emissions from non-road engines offsets the decreases in on-road emissions. See MAG TSD, Table 11-4.

G. VMT TrackingandReporting

CAA section 187(a)(2)(A) requires each State with a serious CO nonattainment area to forecast VMT in the nonattainment area for each year before the attainment year. These forecasts must be developed following guidance issued by EPAin consultation with the U.S. Department of Transportation. This section also requires the plan toprovide for annual updates ofthe forecasts to be submitted along with a report containing estimates ofactual VMT for the year. Weprovided detailed guidance to States regarding the VMT tracking and reporting requirement in "Section 187 VMT Forecasting andTracking Guidance," USEPA, January 1992.

We find thatthe Revised 1999 CO Plan fully complies with CAA section 187(a)(2)(A) and our guidance implementing that section. Specifically, the VMT forecasts in the Revised 1999 CO Plan were developed consistent with applicable EPA guidance including (1) forecasting VMT using a validated network-based travel demand model; (2) clearly identifying a VMT tracking area; (3)estimating actual VMT onHighway Performance Monitoring System (HPMS)traffic counts adjusted in a reasonable manner to coverthe entire VMT tracking area; and (4) committing
to submitting annual reports meeting EPA requirements.

MAG has submitted VMT tracking reports for the years 1999, 2000, and 2001. These reports follow EPA guidance regarding content and procedures for determining actual VMT. All three reports show that VMT levels in the metropolitan Phoenix CO nonattainment area remain within the levels projected in the Revised 1999 CO Plan. See "1999 Vehicle Miles Travel Forecasting andTracking Report," MAG, September 22, 1999 (submitted September 23, 1999); "2000 Vehicle Miles Travel Forecasting and Tracking Report," MAG, September 11, 2000 (submittedSeptember 21, 2000); and "2001 Vehicle Miles Travel Forecasting and Tracking Report," MAG, October 23, 2001 (submitted November 14, 2001). H. TransportationControl MeasuresTo Offset GrowthinEmissions

CAA section 187(b)(2) requires serious area CO plans to identify and adopt "specific and enforceable transportation control strategies and TCMs to offset any growth in emissions from growth in VMT andnumbers of trips" and to achieve reductions in mobile source emissions asnecessary in conjunction with other measures to comply withthe applicable periodic emission reduction and attainment requirements.

We interpret this provision to require that sufficient measures be adopted so that projected motor vehicle CO emissions will never be higher during the CO season in one year than during the CO season in the year before. Where growth in VMT and trips would otherwise cause a motorvehicle emissions upturn, this upturn must be prevented. General Preamble at 13521.

The Revised 1999 CO Plan provides sufficient information for us to conclude that on-road mobile source emissions will decrease from the base year of1994 until the attainment year of2000 and this decrease will occur even before we take into account the additional controls in the Revised 1999 CO Plan. Moreover, the Revised 1999 CO Plan provides for expeditious attainment ofthe CO standard. Therefore, we propose to find that the Revised 1999 CO Plan meets CAA section 187(b)(2).

L Contingency Measures
CAA section 172(c)(9) requires that nonattainment area SIPs provide for the implementation of specific measures to be undertaken ifthe area fails to make RFP or attain byits attainment deadline. CAA section 187(a)(7) requires that serious CO nonattainment area plans also contain contingency measures that would be implemented ifthe area exceeds its vehicle mile traveled (VMT) projections. Both sections require that these contingency measures areto take effect without further actionby the State

orthe Administrator. The Act does not specifyhow many contingency

measures are necessary nor does it specifythe magnitude ofthe emission reductions (or VMT reductions) they
must produce. In policy and in previous rulemaking we have suggested that one appropriate choice ofcontingency

measures wouldbe to provide for the implementation of sufficient VMT reductions or emissions reductions to counteract the effect ofone year's growth in VMT in order to ensure continued progress while theplan was being revised to correct any deficiencies that resulted in a failure to attain, make RFP, orkeep within VMT forecasts. General Preamble at 13532.

Under applicable Agency policy,
states may use already adopted and implemented measures as contingency
measures, provided that those measures' emission reductions are not needed to demonstrate expeditious attainment and/or RFP and are not included in either the attainment orRFP demonstrations. This approach effectively allows for the early implementation ofcontingency

measures. 5

The Revised 1999 CO Plan includes 9 contingency measures, all ofwhich have already been adopted and implemented. See Table Con-1 in the EPA TSD. Collectively these measures result in approximately a 4.1 percent reduction in total CO emissions in 2001 and provide emission reductions from each ofthe largest categories ofCO emissions in the Phoenix area: woodburning, gasoline on-road vehicles, and gasoline nonroad engines. See Revised 1999 CO Plan, p. 9-12.

The annualized VMT growth in the Phoenix area from 2000 to 2005 is projected to be 2.6 percent. On-road mobile source account for 67 percent of the 2000 base case (e.g.,prior to control) CO inventory of714.9 mtpd. Revised 1999 CO Plan, p. 8-12. Therefore, one year's growth in VMT is equivalent to 0.67 x 2.6 percent or 1.7 percent (12.2 mptd)ofthe 2000 base case inventory.

One ofthe eight contingency

measures listed in the Revised 1999 CO Planis no longer applicable. Funding for the lawn mower reduction program ended in FY 2001. Prior to 2001, the program resulted in the retirement ofa large number ofgasoline-powered commercial andresidential lawn

mowers and otherhand-held gasolinepowered equipment.6 However, because these lawnmowers have been presumably replaced with cleaner units earlier then they would otherwise have been replaced, the program will have continuing effects for several years after 2000.

The use ofan adopted and implemented federal program, the national LEV program, as a contingency

measure is acceptable. The purpose of contingency measures is to assure continued progress towards attainment

5See memorandum, G. T. Helms, Chief, Ozone/ Carbon Monoxide Programs Brand, OAQPS to Air Branch Chiefs, Regions I-X, "Early Implementation ofContingency Measures for Ozone and Carbon Monoxide (CO) Nonattainment Areas," August 13, 1993 ("Helms memo").

6In 1998/99, the program retired 1780 old, polluting gas mowers and 563 otherpieces of garden equipment. See "Current Status ofCarbon Monoxide," Maricopa County Environmental Services Department, (January 2000). 

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in an area while its SIP isbeing revised
to correct for a failure to attain or to make RFP orto deal withhigher than expected VMT growth. To the extent that federal programs provide for this continued progress and the State has not otherwise relied on theprogram to demonstrate attainment or RFP, the State may rely on thatmeasure. 7

We have approved the other seven contingency measures into the Arizona SIP in earlier rulemakings. See 67 FR 48718 (July 25, 2002) and 68 FR 2912 (January 22, 2003).

Because the contingency measures collectively provide for emission reductions consistent with EPApolicy and meet the statutory requirement that they "take effect without further action by the State or the Administrator," we propose to find thatthe Revised 1999 CO Plan meets the CAA sections 172(c)(9) and 187(a)(7) requirement for contingency measures. We also propose to find that the emissions reductions resulting from these contingency

measures are not already accounted for in the Phoenix CO nonattainment area's RFP or attainment demonstrations.

J.EnhancedI/MProgram

CAA section 187(b)(6) requires that all serious CO nonattainment areas implement an enhanced I/Mprogram which complies with EPA guidance. We issued our initial rule containing the requirements for enhanced I/M programs in 1992 and have amended those rules several times since. Formore information on therequirements for enhanced I/Mprograms, see 60 FR 22518 (May 8, 1995) (initial approval of Arizona's enhanced and basic I/M program) and 67 FR 52433 (August 12, 2002) (proposed approval ofrevisions to Arizona's enhanced and basic I/M program).

Arizona first submitted the legislation andregulations for the Maricopa County enhanced vehicle emission inspection
program in 1994 as part ofits moderate

area plans for CO and ozone. Subsequently, Arizona made a number ofmodifications to itsprogram including revising the testing protocol, requiring on-board diagnostic system testing, expanding the exemption to the latest five model years, changing the waiver provisions, andremoving the
remote sensing element ofthe program. The State resubmitted the program for approval in 2001. See 2001 I/M submittal.

7 However, ifthe federal program is delayed or does not generate the expected emission reductions, the Statewould have to revise its contingency

measures to assure adequate emission reductions or face a finding ofSIP inadequacy. In a separate action, we approved Arizona's vehicle emission inspection program for the Phoenix area as meeting the enhanced I/M program requirements ofCAA section 187(b)(6) and our regulations. See 68 FR 2912 (January 22, 2003).

K. WintertimeOxygenated Gasoline Program

CAA section 211(m) requires states with CO nonattainment areas with design values of9.5 ppm or higher to implement a wintertime oxygenated gasoline program requiring that gasoline contain not less than 2.7 percent oxygen by weight. All serious CO nonattainment areas, which by definition have design values exceeding the 211(m) thresholds, must include an oxygenated gasoline program in their SIPs. See also CAA § 187(b)(3). Under both 211(m) and 187(b)(3), theprogram is to apply to all gasoline sold, supplied, offered for sale or supply, dispensed, transported orintroduced into

commerce in the consolidated metropolitan statistical area (CMSA) or, ifno CMSA exists, the metropolitan statistical area (MSA).

1.History ofState Program

Arizona first adopted a wintertime oxygenated gasoline program in 1988, before sections 187(b) and 211(m) were added to the Act aspart ofthe 1990 Clean Air Act Amendments. The original State wintertime oxygenated gasoline program applied throughout Maricopa County and established a fairly complicated scheme of shifting averages and exemptions. In general, however, itrequired leaded gasoline to contain between 2.4 and 3.7 percent oxygenby weight andunleaded gasoline
to contain between 1.9 and 3.7percent oxygenby weight. The program applied from September 30 through March 31 of each year.EPA approved this program into the SIP finding the fuel control

measure was not preempted under CAA section 211(c)(4) andwould, in any event, provide necessary CO emission reductions. See 53 FR 30224 (Aug. 10, 1988).

The August 10, 1988 SIP approval, however, was vacated by the Ninth Circuit Court ofAppeals in Delaneyv. EPA, 898 F.2d 687 (9thCir. 1990). In 1991, in response to an order from the court, EPA disapproved the Maricopa CO SIP including the State's wintertime oxygenated gasoline requirement. 56 FR 5458 (Feb. 11, 1991). In itsplace, EPA adopted aFIP with an oxygenated gasoline program. EPA modeled the FIP
program onthe then newly adopted requirements in 211(m). It required all gasoline sold in the Maricopa nonattainment area to contain a minimum oxygen content of2.7 percent by weight from October 1toMarch 31 ofeach year. In the FIP notice, we noted that section 211(m) addedby the 1990 Clean Air Amendments would require Maricopa to adopt a similar state requirement beginning in 1992. As a result, we anticipated thatthe oxygenated gasoline requirement in the FIP would only be in effect for one year.

Arizona adopted new oxygenated gasoline requirements on June 11, 1991 in Arizona House Bill 2181. On March 9, 1992, EPA approved Arizona's revised wintertime oxygenated gasoline
program into the SIP. 57 FR 8268. The revised program required that all gasoline in the Maricopa nonattainment

area contain no lessthan 2.7 percent oxygenby weight from September 30 to March 31 of each year. In that approval, EPAnoted thatthe area covered by the
program did not include the entire MSA

as required under section 211(m). Instead, the program applied only tothe Maricopa CO nonattainment area, which

was then defined as the MAG urban planning area. As aresult, we found the State program couldbe approved into the SIP as an equivalent substitution for the FIP programbut concluded that Arizona would need to modify the
program furtherby November 1, 1992 in order to meet all the requirements of 211(m). Id.

Since our March 1992 approval, Arizona has made anumber ofchanges
to the wintertime oxygenated gasoline
program. In 1998, EPA approved changes to the wintertime program as part ofour approval ofthe State's new CleanerBurning Gasoline (CBG) program. 63 FR 6653 (Feb. 10, 1998). The wintertime program approved at thattime continued to require that gasoline supplied or sold in the Maricopa CO nonattainment area 8 contain a minimum 2.7 percent oxygen by weight, but changed the control period to November 1through March 31. In our approval, we did not address compliance with 211(m), instead finding the revisions necessary for attainment ofthe ozone andPM-10 NAAQS.

On March 4, 2004, we approved into the SIP furtherrevisions to the State CBGprogram, including changes to the wintertime oxygenated gasoline

8Therevised rules established new defined
"areas" for specifying the applicabilityoftheir requirements. The wintertime oxygenated gasoline requirements apply to "Area A", which was originally defined as the Maricopa County CO nonattainment area. As explained below,Arizona has made a number ofchanges to the definition of Area Ato affect the applicabilityof the fuel requirements. 

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requirements. 69 FR 10161. The current SIP-approved wintertime program requires all gasoline sold in Maricopa County and in parts ofPinal and Yavapai Counties from November 1to March 31 to contain a minimum of 3.5 percent oxygen by weight. Although Arizona's wintertime CBG program adopted by the State on July 18, 1988 covered the MSA, as required by 211(m), subsequent changes tothe covered area thathave been approved into the SIP (i.e.,the inclusion of portions ofYavapai and Pinal Counties) donot correspond to the entire MSA, which itselfhasbeen subsequently modified by the Census Bureau.9

2.Compliance With 211(m)

The State's wintertime oxygenated gasoline program approved in the SIP has provided significant CO emissions reductions in the Maricopa CO nonattainment area and has helped the

area attain the CO NAAQS, as evidenced by the Phoenix area's lack of violations ofthe CO standard since 1997, when the program was initiated. As a result, we are proposing to find that further changes to theprogram to meet the specific requirements of 211(m), including therequirement that the program apply tothe entire MSA,

are not required under the Act.

Section 211(m)(6) provides: Nothing in this subsection shallbe interpreted as requiring an oxygenated gasoline program inan area whichis in attainment for carbon monoxide, except that in acarbon monoxide nonattainment area which isredesignated as attainment for carbonmonoxide, therequirements ofthis subsection shallremain in effect tothe extent suchprogram isnecessary tomaintain such standardthereafter inthe area.

See also CAA section 187(b)(3)(B) (providingthat a wintertime oxygenated program is not required for an area ifthe State demonstrates thatthe revision is
not necessary for attainment and maintenance ofthe CO NAAQS). We have interpreted this language to mean that once EPA determines that a CO nonattainment area is actually attaining the CO NAAQS andthe area demonstrates itdoes not need a program meeting 211(m), section 211(m) no longer requires submittal ofa SIP revision so long as the area continues to maintain the standard. See, e.g., 60 FR 62741 (Dec. 7, 1995) (waiving 211(m) requirements for portions ofthe Camden, New Jersey area).

Today's finding thatthe State need
not submit a program complying with section 211(m) does not mean the State

9AllofPinalCountywas added tothe definition of the Phoenix-Mesa MSA by the 1990census. can abandon its wintertime oxygenated gasoline program. The program remains approved in the SIP. Any revision to

remove these requirements from the SP would be subject to the requirements of section 110(1).

L. GeneralSIPRequirements

CAA section 110(a)(2)(C) requires SIPs toinclude aprogram to provide for the enforcement of SIP measures. Section 110(a)(2)(E)(i) requires that SIPs provide necessary assurances that the State (orthe general purpose local government) will have adequate personnel, funding and authority under State law toimplement the submitted SIP. Finally, section 110(a)(2)(E)(iii) requires SIPs to include necessary

assurances that where a State has relied

on alocal or regional government, agency orinstrumentality for the implementation of any plan provision, the State has responsibility for ensuring adequate implementation oftheplan provision.

The principal control measures in the Revised 1999 CO Plan are Arizona's VEI program, the wintertime CBG program, andMaricopa County's woodburning restrictions program. We approved these programs at 68 FR 2912 (January 12, 2003), 69 FR 10161 (March4, 2004), 64 FR 60678, and 67 FR 48718 (July 25, 2002) respectively. As part ofour approval actions, we found that Arizona had adequate personnel, funding and authority toimplement these programs andhad adequately provided for the enforcement ofthese programs.

We have previously found that Arizona law includes the necessary

assurances that where a State has relied

on alocal or regional government agency orinstrumentality for the implementation of any plan provision, the State has responsibility for ensuring adequate implementation oftheplan provision. 60 FR 18010, 18019 (April 10, 1995).

V. The CAA's Requirements for Serious CO Maintenance Plans and Redesignation Requests

Under the Clean Air Act, we can change designations ifacceptable data

are available and ifcertain other requirements aremet. See CAA Section 107(d)(3)(D). Section 107(d)(3)(E) ofthe CAA provides that the Administrator
may promulgate a redesignation ofa nonattainment area to attainment ifthe following five criteria are met: (i) The Administrator determines that the area has attained the national ambient air quality standard;

(ii)The Administrator has fully approved the applicable implementation plan for the area under CAA section 110(k);

(iii)The Administrator determines thatthe improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation ofthe applicable implementation plan and the applicable Federal airpollutant control regulations and other permanent and enforceable reductions;

(iv)The Administratorhas fully approved a maintenance planfor the

area as meeting the requirements of CAA section 175A; and

(v)The State containing the area has
met all requirements applicable to the

area under section 110 andpart D ofthe CAA.

Before we can approve the redesignation request, we must determine that all applicable SIP elements have been fully approved. Approval ofthe applicable SIP elements may occur simultaneously with the final approval ofthe redesignation request.
VI.The MAG CO Redesignation Request and Maintenance Plan's Compliance Withthe CAA's Requirements for CO Redesignation Requests andMaintenance Plans

We are proposing to approve theMAG CarbonMonoxideRedesignation RequestandMaintenance Plan forthe MaricopaCountyNonattainment Area, May 2003 ("MAG CO Redesignation Request andMaintenance Plan"). The MAG CO Redesignation Request and Maintenance Plan was developed by the Maricopa Association ofGovernments (MAG), the lead air quality planning
agency in Maricopa County. The Arizona Department ofEnvironmental Quality (ADEQ) submitted this plan as

a revision to the Arizona SIP onJune 16, 2003 and EPA received it onJune 24, 2003. We refer to thisplan in this document as the MAG CO redesignation request and maintenance plan, the MAG maintenance plan, orvariations ofthese.

As submitted, the MAG CO Redesignation Request and Maintenance Plan consists ofthe mainplan document and one volume oftechnical appendices. The MAG CO Redesignation Request and Maintenance Plan contains 1994 and 1999 emission inventories and projected inventories for 2006 and 2015, a modeling demonstration showing maintenance of the CO standard through 2015, a list of committed control measures, mobile

source emissions budgets for 2006 and 2015, and contingency measures. Ituses UAM and the CAL3QHC microscale model to model air quality in 1994 as

abase year and in 2006 as an interim
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and demonstrates maintenance ofthe CO standard through 2015.

The MAG CO Redesignation Request andMaintenance Plan shows thatthe principal sources contributing to past CO exceedances are gasoline on-road
motor vehicles, gasoline non-road engines, and woodburning. MAG CO Redesignation Request andMaintenance Plan, p. ES-5.

In earlier actions, we have already approved revisions toArizona's CBG program andto Arizona's VEIprogram

as well as the Maricopa County Woodburning curtailment program. 69 FR 10161 (March 4, 2004), 68 FR 2912 (January 22, 2003), 64 FR 60678 (November 8, 1999) and 67 FR 48718 (July 25, 2002). The revisions to these programs are the principal controls relied on in the MAG CO Redesignation Request and Maintenance Plan to demonstrate attainment. We have also previously approved the commitments by the Phoenix area cities and towns to adopt and/orimplement CO control

measures. We approved these commitments as part ofthe serious area PM-10 plan approval on July 25, 2002
at67 FR 48718. See 40 CFR 52.120(c)(100).

We have reviewed the MAG CO Redesignation Request andMaintenance Plan and believe that proposing to approve the request is warranted, consistent with the requirements of CAA section 107(d)(3)(E). The following sections ofthis notice describe how the requirements of section 107(d)(3)(E) are addressed by the MAG submittal.

A. GeneralSIPRequirements

Section 110(k) ofthe CAA addresses

our actions on submissions ofrevisions
to a SIP. The CAA requires States to observe certain procedural requirements in developing SIP revisions for submittal tous. Section 110(a)(2) ofthe CAA requires that each SIP revision be adopted afterreasonable notice and public hearing. This must occur prior to the revisionbeing submittedby a State
to us.

MAG held a public hearing for the MAG CO Redesignation Request and Maintenance Plan on May 5, 2003. The MAG Regional Council adoptedthe MAG CO Redesignation Request and Maintenance Plan on May 28, 2003. These SIP revisions were adopted and submittedby ADEQto us onJune 16, 2003. We received the submittal onJune 24, 2003.

We have evaluated MAG's submittal andhave determined that the State met the requirements for reasonable notice andpublic hearing under section 110(a)(2) ofthe CAA. The MAG CO Redesignation Request andMaintenance Plan was deemed complete by operation oflaw six months after the submittal date.

B.AttainmentoftheCONAAQS
Section 107(d)(3)(E)(i) ofthe CAA
states that for an area to be redesignated
to attainment, the Administrator must determine thatthe area has attained the applicable NAAQS. As described in 40 CFR part 50.8, the national primary ambient air quality standard for carbon monoxide is 9 parts per million (10 milligrams per cubic meter) for an 8- hour average concentration not to be exceeded more than once per year.40 CFR part 50.8 continues by stating that the levels ofCO in the ambient air shall be measured by areference method based on40 CFR part 50, Appendix C and designated in accordance with 40 CFR part 53. We consider an area tobe in attainment ifeach ofthe CO ambient air quality monitors in the area does not have more than one exceedance ofthe CO standard over a one-year period. See 40 CFR part 50.8 and 40 CFR part 50, Appendix C. Ifany monitor in the area's CO monitoring network records more than one exceedance ofthe CO standard during a one-year calendar period, then the area is inviolation ofthe CO NAAQS.

In addition, our interpretation ofthe CAA and EPAnational policy has been that an area seeking redesignation to attainment must show attainment ofthe CO NAAQS for at least a continuous two-year calendar period. In addition, the area must also continue to show attainment throughthe date that we promulgate the redesignation in the Federal Register.

December 31, 2000 was the attainment date for the Maricopa County serious CO nonattainment area. We published afinding of attainment ofthe CO standard for the Maricopa County nonattainment area on September 22, 2003 (see 68 FR 55008). In our finding,

we noted thatnot onlydid Maricopa County have the required clean data for the two years preceding the attainment date, but also thatthe Maricopa County nonattainment area hasbeen in attainment forthe national standards for CO since 1997. Further information on CO monitoring is presented in Chapter 3,page 3-15 ofthe MAG CO Redesignation Request andMaintenance Plan, and in our finding of attainment (see 68 FR 55008, September 22, 2003).

Therefore, we believe the Maricopa County area has met the first component for redesignation: demonstration of attainment ofthe CO NAAQS. We note too thatMAG has indicated in the MAG CO Redesignation Request and Maintenance Plan that ADEQ and MCESD will continue to operate an appropriate air quality monitoring network ofNational Ambient Monitoring Stations (NAMS) and State and Local AirMonitoring Stations (SLAMS) monitors in accordance with 40 CFR Part 58 to verify the continued attainment ofthe CO standard.

C.MeetingApplicableRequirementsof Section 110 andPart D
To be redesignated to attainment, section 107(d)(3)(E)(v) requires that an

area must meet all applicable requirements under section 110 and part D ofthe CAA. We interpret section 107(d)(3)(E)(v) to mean that for a redesignation to be approved byus, the State mustmeet all requirements that applied to the subject area prior to or at the time of submission ofa complete redesignation request.
1.CAA Section 110 Requirements

The Maricopa County nonattainment

area was initially classified as moderate for CO. MAG submitted the 1993 Carbon Monoxide Plan by November 15, 1993 in order to meet the moderate area requirements. An addendum to this planwas submitted in March 1994. On July 29, 1996, the nonattainment area

was reclassified to serious effective August 28, 1996 due to failure to attain the CO standard byDecember 31, 1995. The new attainment date was December 31, 2000.

OnJuly 8, 1999, ADEQsubmitted the 1999 CO Planto EPA. This submittal contained an attainment demonstration for December 2000. The submittal was found complete on September 9, 1999.

During the 2000 legislative session, the Arizona Legislature passed House Bill (HB) 2104, which repealed the Random Onroad Testing Requirements (Remote Sensing Program) from the Vehicle Emissions Inspection (VEI)
program. EPA indicated that the 1999 CO Plan would have tobe revised to reflect this legislative change. MAG conducted new air quality modeling and documented the impact ofthe repeal of the remote sensing program in the Revised 1999 CO Plan, dated March 2001.

On March 30, 2001, ADEQ submitted the Revised 1999 CO Plan to EPA. We foundthe submittal complete on October 9, 2001. We have analyzed the SIP elements in the Revised 1999 CO Planthat we areproposing for approval

as part our action today, and have determined thatthey comply with the relevant requirements ofsection 110(a)(2).

OnJune 16, 2003, ADEQsubmitted theMAG CarbonMonoxide RedesignationRequestand 

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MaintenancePlan fortheMaricopa CountyNonattainment Area,May 2003. The submittal was deemed complete by operation oflaw six months after receipt by EPA.

2.Part D Requirements

Before the Maricopa County serious CO nonattainment area may be redesignated to attainment, the State
must have fulfilled the applicable requirements ofpart D. Under part D, an area's classification indicates the requirements to which it was subject. Subpart 1ofpart D sets forth thebasic nonattainment requirements applicable
to all nonattainment areas. Subpart 3of part D contains specific provisions for serious CO nonattainment areas.

The relevant subpart 1requirements

are contained in sections 172(c) and 176. Our General Preamble (see 57 FR 13529, 13533, April 16, 1992) provides EPA's interpretation ofthe CAA requirements for serious CO nonattainment areas.

The General Preamble provides that the applicable requirements ofCAA section 172 are 172(c)(3) [emissions inventory], 172(c)(5) [the section 110(a)(2) air quality monitoring requirements], and 172(c)(9) [contingency measures]. Itis also worth noting that we interpret the requirements of sections 172(c)(2) [reasonable further progress-RFP] and 172(c)(6) [other measures] asbeing irrelevant to a redesignation request because they only have meaning for an

area thatis not attaining the standard. 10 Finally, the State has not sought to exercise the options that would trigger sections 172(c)(4) [identification of certain emissions increases] and 172(c)(8) [equivalent techniques]. Thus, these provisions are also not relevant to the redesignation request.

Regarding the requirements of sections 172(c)(3) [emissions inventory] and 172(c)(9) [contingency measures], please refer to our discussion below of sections 187(a)(1) and 187(a)(3), which

are provisions ofsubpart 3ofpart D of the CAA that address the same requirements as sections 172(c)(3) and 172(c)(9).

For the section 172(c)(5) New Source Review (NSR)requirements, the CAA requires allnonattainment areas to meet several requirements regarding NSR, including provisions to ensure that increased emissions will not result from any new or modified major stationary

sources and a general offset rule. We

10

SeeEPA's September 4, 1992 John Calcagni
memorandum entitled "Procedures for Processing Requests to Redesignate Areas to Attainment", and the General Preamble, 57 FRat 13564, dated April 16, 1992. have determined that areas being redesignated from nonattainment to attainment do not need to comply with the requirement that an NSR programbe approved prior toredesignation provided that the area demonstrates maintenance ofthe standard without part D nonattainment NSR in effect. The rationale for this decision is described in amemorandum from Mary Nichols dated October 12, 1994 ("PartD New Source Review (partD NSR) Requirements for Areas Requesting Redesignation to Attainment"). We have determined that the maintenance demonstration for Maricopa County does not rely onnonattainment NSR. Therefore, the State need not have a fully-approved nonattainment NSR
program prior to approval ofthe redesignation request.

Prevention of Significant Deterioration (PSD)is the replacement for NSR, and part ofthe obligation under PSD is for a new source to review increment consumption and maintenance ofthe air quality standards. The PSD program requires stationary sources to undergo preconstruction review before facilities

are constructed ormodified, and to apply Best Available Control Technology (BACT). This program will apply to any major source wishing to locate in the Maricopa County area once the area is redesignated to attainment. Effective November 22, 1993, we delegated PSD authority to Maricopa County via a PSD Delegation Agreement (59 FR 1730, January 12, 1994).

For the CAA section 172(c)(7) provisions [compliance withthe CAA section 110(a)(2) air quality monitoring requirements], our interpretations are presented in the General Preamble (57 FR 13535). CO nonattainment areas are to meet the applicable air quality monitoring requirements of section 110(a)(2) ofthe CAA.

Information concerning CO monitoring in the Maricopa County nonattainment area isincluded in the Monitoring Network Review (MNR) prepared byMCESD and submitted to EPA. In Chapter 3,page 3-15 ofthe MAG CO Redesignation Request and Maintenance Plan, MAG commits to the continued operation ofthe existing NAMS and SLAMS CO monitors run by ADEQ and MCESD, according to all applicable Federal regulations and guidelines, even afterthe Maricopa County area is redesignated to attainment for CO. Annual review ofthe NAMS/SLAMS air quality surveillance system will be conducted in accordance with 40 CFR 58.20(d) to determine whether the system continues to meet the monitoring objectives presented in Appendix D of40 CFR Part 58.

Section 176 ofthe CAA contains requirements related to conformity. Although EPA's regulations (see 40 CFR 51.396) require that states adopt transportation conformity provisions in their SIPs for areas designated nonattainment or subject to an EPAapproved maintenance plan, we have decided that a transportation conformity SIP is not an applicable requirement for purposes ofevaluating a redesignation request under section 107(d) ofthe CAA. This decision isreflected in EPA's 1996 approval ofthe Boston carbon monoxide redesignation (See61 FR 2918, January 30, 1996).

The relevant subpart 3provisions

were created when the CAA was amended on November 15, 1990. The

new CAArequirements for serious CO
areas, such as Maricopa County, required that the SIP be revised to include a 1990 base year emissions inventory (CAAsection 187(a)(1)), vehicle miles traveled tracking (CAA section 187(a)(2)(A)), contingency provisions (CAA section 187(a)(3)), corrections to existing motor vehicle inspection andmaintenance (I/M) programs (CAA section 187(a)(4)), periodic emissions inventories (CAA section 187(a)(5)), enhanced motor vehicle I/M program (CAA section 187(a)(6)), a modeled attainment demonstration with specific annual emissions reductions (CAA section 187(a)(7)) and the implementation ofan oxygenated fuels program (CAAsection 211(m)). How the State met these requirements and our approvals are described earlier in this notice.

Regarding section 187(a)(1) ofthe CAA (baseyear emissions inventory), the State submitted a SIP revision for a 1990 base year inventory (annual and average daily emissions) as well as projected 1995 and 2005 inventories for the entire Maricopa County nonattainment area on November 15, 1993 as part ofthe MAG 1993 Carbon MonoxidePlan fortheMaricopaCounty Area ("COPlan").On April 4, 1994, ADEQsubmitted updated and improved inventories as part ofMAG's 1993 Carbon Monoxide Plan for the Maricopa County AreaAddendum ("Addendum")." These revised

11On August 9, 1993, EPA had issued a SIP call undersection 110(k)(5) ofthe CAA that required Arizona to submit a plan to EPA that demonstrated attainment ofthe CO NAAQS in the Phoenix area by December 31, 1995. As an area witha design value less than 12.7 ppm, the Statewould not otherwise have been required to submit an attainment plan for the Phoenix area. See section 187(a). CAA section 187(a)(1) requires the submittal ofa comprehensive, accurate, current inventory of
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inventories reflected adjustments to growth factors and the impact of

measures in Arizona House Bill 2001. Both submittals became complete by operation oflawunder CAA section 110(k)(1)(B) on May 15, 1994 and October 8, 1994, respectively.

We proposed approval ofthe 1990 base year inventory on September 18, 1996 (61 FR 49087), and did not receive any comments on ourproposed action. We will finalize thatproposed action in

our final rulemaking on today's proposed rule.

Regarding section 187(a)(5) ofthe CAA (periodic emissions inventories),

see Section IV.B. "Emission Inventory" ofthis Federal Register notice for information on the 1993 and 1996 emissions inventories for Maricopa County for CO. We are proposing to approve these inventories in our action today.

D.Fully-ApprovedSIP UnderSection 110(k) ofthe CAA

Section 107(d)(3)(E)(ii) ofthe CAA
states that for an area tobe redesignated
to attainment, it mustbe determined that the Administrator has fully approved the applicable implementation plan for the area under section 110(k).

As noted above, in today's action EPA is approving the SIP revision demonstrating attainment for the Maricopa County serious CO nonattainment area that was required by the CAA. The bump-up ofthe Maricopa County CO nonattainment area from moderate to serious for CO superceded the remaining moderate CO nonattainment area requirements for the

area. Thus, with a final rule to approve the Maricopa County attainment demonstration, redesignation request, and maintenance plan, we will have fully approved the Maricopa County CO element ofthe SIP under section 110(k) ofthe CAA.

E.ImprovementinAirQualityDue to PermanentandEnforceable Measures
Section 107(d)(3)(E)(iii) ofthe CAA provides that for an area tobe redesignated to attainment, the Administrator must determine thatthe improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation ofthe applicable implementation plan, implementation ofapplicable Federal airpollutant control regulations, and other permanent and enforceable reductions.

actual emissions forall CO nonattainment areas whether ornot they have a separate requirement to submit an attainment demonstration. As part ofour action today, we are approving the Revised 1999 CO Plan. This plan is primarily based on emissions reductions from the wintertime oxygenated fuels program, the VEIprogram, traffic synchronization, and intelligent transportation systems (ITS)measures. These programs are further described in Chapter Five ofthe Revised 1999 CO Plan.

As described in Chapter Two, pages 2-11 to 2-15 ofthe MAG CO Redesignation Request andMaintenance Plan, significant additional emissions reductions were realized from Maricopa County's basic inspection and maintenance program (applicable to vehicles 1966 andnewer), and beginning in 2000, the enhanced I/M program (applicable to vehicles 1966 and newer, with an exemption for vehicles ofthe five mostrecent model years). Oxygenated fuels are gasolines that

are blended with additives that increase the level ofoxygen in the fuel and consequently reduce CO tailpipe emissions. Arizona's Cleaner Burning Gasoline (CBG) rule contains the oxygenated fuels provisions for the Maricopa CO nonattainment area. As approved byEPA on March 4, 2004 (see 69 FR 10161), Arizona's CBG program requires allMaricopa County-area gas stations in Area A 1 2 to sell fuels containing a 3.5 percent minimum oxygen content (byweight) during the wintertime season, which runs from November 2toMarch 31 ofeach year.

Maricopa County has also been implementing the requirements ofits clean burning fireplace ordinances. The Arizona legislature passed SB 1427 in 1998 which required cities, towns, and counties in Area Ato adopt, implement, and enforce an ordinance thatcomplies with MAG's clean burning fireplace standards byDecember 31, 1998. The ordinance allows only the use of permanently-installed gas or electric log inserts, fireplaces, woodstoves, or other appliances that are certified byEPA, tested andlisted by anationally recognized testing agency to meet federal performance standards, or determined by the Maricopa County Control Officer tomeet federal performance standards.

We have evaluated the various State andFederal control measures, the original 1990 base year emission inventory, andthe 1993, and 1996 periodic emissions inventories, and

12Area Aincludes the urbanized portion of Maricopa County, a small portion of southern Yavapai County, and the western portions ofPinal County. believe thatthe improvement in air quality in the Maricopa County nonattainment area has resulted from emissions reductions that are permanent and enforceable.

F. Fully-ApprovedMaintenancePlan UnderSection 175A

Section 107(d)(3)(E)(iv) ofthe CAA provides that for an area to be redesignated to attainment, the Administrator must have fully approved

a maintenance plan for the area meeting the requirements of section 175A ofthe CAA.

Section 175A ofthe CAA sets forth the elements ofa maintenance planfor

areas seeking redesignation from nonattainment to attainment. The maintenance plan must demonstrate continued attainment ofthe applicable NAAQS for at least ten years afterthe Administrator approves a redesignation
to attainment. Eightyears afterthe promulgation ofthe redesignation, the State must submit arevised maintenance plan that demonstrates continued attainment for the subsequent ten-year period following the initial tenyear maintenance period. To address the possibility offuture NAAQS violations, the maintenance plan must contain contingency measures, with a schedule for adoption and implementation, that

are adequate to assure prompt correction ofaviolation. In addition, we issued further maintenance plan interpretations in the "General Preamble for the Implementation ofTitle I ofthe Clean Air ActAmendments of 1990" (57 FR 13498, April 16, 1992), "General Preamble for the Implementation of TitleI ofthe Clean Air Act Amendments of1990: Supplemental" (57 FR 18070, April 28, 1992), and the EPA guidance memorandum entitled "Procedures for Processing Requests to Redesignate Areas toAttainment" fromJohn Calcagni, Director, Air Quality Management Division, Office ofAir Quality Planning and Standards, to Regional Air Division Directors, dated September 4, 1992 (hereafter referred to

as the "Calcagni memo"). In this Federal Register action, EPA is proposing approval ofthe maintenance planfor the Maricopa County CO nonattainment area because we believe,

as detailed below, that MAG's CO Redesignation Request and Maintenance Plan submittal meets the requirements ofsection 175A and is consistent with the documents referenced above. Our analysis ofthe pertinent maintenance planrequirements, with reference to MAG's CO Redesignation Request and Maintenance Plan, isprovided below. 

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1.Emissions Inventories-Attainment Year and Projections

EPA's interpretation ofthe CAA section 175A maintenance plan requirements are generally provided in the General Preamble (see 57 FR 13498, April 16, 1992) and the Calcagni memo referenced above. Under our interpretations, areas seeking to redesignate to attainment for CO may demonstrate future maintenance ofthe CO NAAQS either by showing that future CO emissions willbe equal to or less than the attainment year emissions

orby providing a modeling demonstration. However, under the CAA, many areas (suchas Maricopa County) were required to submit a modeled attainment demonstration to show thatreductions in emissions would be sufficient to attain the applicable NAAQS. For these areas, the maintenance demonstration is to be based onthe same level ofmodeling (see the "Calcagni memo"). For the Maricopa County area, this involved the

use ofEPA's Urban Airshed Model (UAM)in conjunction with intersection hotspot modeling using the CAL3QHC model.

The MAG CO Redesignation Request andMaintenance Plan submittedby ADEQ on June 16, 2003 included comprehensive emissions inventories of CO emissions for the Maricopa County

area. These inventories include emissions from stationary point sources,

area sources, non-road mobile sources, and on-road mobile sources. MAG used the 1994 base year inventory, from the Revised 1999 CO Planreceived byEPA

on April 2,2001, and included an interim-year projection for 2006 along with the final maintenance year of2015. More detailed descriptions ofthe 1994 base year inventory from the Revised 1999 CO Plan, the 2006 projected inventory, andthe 2015projected inventory are documented in the MAG redesignation request and maintenance plan onpage 3-8, and in the State's TSD in Appendix A, Exhibit 1. The State's submittal contains detailed emission inventory information that was prepared in accordance with EPA guidance. Summary emissions figures from the 1994 base year, the 2015 maintenance year and the interim projected year 2006

are provided in Table 2below.

TABLE 2.-SUMMARY OF CO EMISSIONS IN TONS PER DAY FOR MARICOPA COUNTY [For a Friday in December]

1994 2006 2015

Poin t sources ........................................................................................................................................... 2.5 21.9 32.2 Area sources ............................................................................................................................................ 21.0 29.7 36.2 Non-road mobile sources ........................................................................................................................ 155.1 161.0 169.9 On-road mobile sources .......................................................................................................................... 869.6 699.7 662.9

Total*

................................................................................................................................................ 1048.2 912.3 901.2 *Total may not equal 100% due to rounding.

We note thatbased on the information in Table 2, minorincreases are projected in years 2006 and 2015 for point sources and area sources. The most significant reductions in the emissions inventory

come from the on-road mobile sources category. Since two ofthe MAG CO Redesignation Request andMaintenance Plan's most significant measures reduce on-roadvehicle emissions, namely the cleaner burning gasoline and vehicle emissions inspection programs, these projected emissions reductions are reasonable. MAG's approach follows EPA guidance on projected emissions, and we believe itis acceptable. Further information on these projected inventories may also be found on page 3-9 ofthe MAG CO Redesignation Request and Maintenance Plan and in Appendix A, Exhibit 2, Section III-1 of the TSD.

2.Demonstration ofMaintenance

The Calcagni memo states that where modeling was relied on to demonstrate maintenance, the plan isto contain a summary ofthe air quality concentrations expected to result from the application ofthe control strategies. Also, the plan isto identify and describe the dispersion model or other air quality model used to project ambient concentrations. For the MAG CO maintenance demonstration, MAG used UAM, the standard model for 1-hour CO attainment demonstrations, consistent with EPA guidance in Guideline for RegulatoryApplication ofthe Urban AirshedModelforAreawideCarbon Monoxide (EPA-450/4-92-011a and b, June 1992; hereafter "Guideline"). Most ofthe inputs for the modeling in the MAG CO Redesignation Request and Maintenance Plan were identical to those in the Revised 1999 CO Plan. The main differences were in mixing height and in the emissions inputs.

In the MAG CO Redesignation Request andMaintenance Plan, the UAM model's maximum model height

was increased slightly to accommodate plume rise from growth in peaking
power plants. This adjustment has a relatively small effect on ground-level CO concentrations. Diagnostic and sensitivity testing showed reasonable agreement with observations after adjustment ofthe DIFFBREAK parameter, which in UAM is similar to mixing height, the height above ground through which substantial mixing

occurs. Adjustment ofminimum mixing heights isnot ideal, but may be unavoidable in the absence ofspecific measured data on mixing heights, and has been accepted in other CO plans. Since CO is chemically inert,it isnot unreasonable to adjust the air volume available for CO dilution, and thereby adjust CO concentration. This assumes diagnostic testing for othermodel inputs hasbeen done, asis the case here.

MAG's emission input development
process used EPA's MOBILE6 model to estimate on-road mobile source emission factors instead ofMOBILE5,
perEPA guidance, and newer traffic data were used. Total estimated CO emissions are substantially larger due to the changes in MOBILE model and various traffic and otherinputs. On-road emissions for the 1994 episode increased 73%; total emissions from all

sources increased 52%. However, modeled peak CO concentrations increased only slightly. Several factors
account for the apparent discrepancy between input emissions and output model peak.

First, per EPA guidance, MOBILE6

was used to estimate on-road emissions instead ofthe older MOBILE5a. One effect mitigating the higherMAG CO maintenance plan emissions is that while the base case (1994) on-road emissions are higher, they decline faster thanin the Revised 1999 CO Plan because ofthe enhanced effects of vehicle fleetturnover incorporated in MOBILE6. So higher initial emissions in 

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the MAG CO Redesignation Request and Maintenance Plan are still consistent with maintenance ofthe CO NAAQS later.

Second, the higher emissions in the MAG CO Redesignation Request and Maintenance Plan do not translate into increased peak CO concentrations. Mainly, the higher emissions in the MAG CO Redesignation Request and Maintenance Plan are shifted in time, and spread over a large area and volume; these mitigate the peakincreasing effect ofthe increased emissions. Revised traffic counts show that more ofthe emissions occur during the morning commute than during the evening. As a result, the increased emissions occur earlier in the day, farther from the peak in the 8-hour average, which occurs at 3a.m. The assumed spatial distribution ofcold
start emissions was also different than in the Revised 1999 CO Plan. In the MAG CO Redesignation Request and Maintenance Plan, cold start emissions

were distributed to local and arterial roads, but not to freeways; in the Revised 1999 CO Plan, the emissions

were distributed to all three facility types. The method used in the MAG CO Redesignation Request andMaintenance Plan is more realistic because cold start emissions occur relatively close to the beginning oftrips, when commuting

cars are more likely tobe on local roads than onfreeways. Another effect ofthis different spatial allocation ofemissions is thatthey are more dispersed. Because ofthis and because ofchanges in various othermodel inputs, CO emissions are more widely distributed in the MAG CO Redesignation Request andMaintenance Plan.

Finally, as mentioned above, mixing height was increased to improve model performance. This provided agreater volume for dilution ofCO emissions, andthus a lower ambient concentration.

A third factor in reconciling higher emissions with arelatively unchanged peak concentration isthat, the MAG CO Redesignation Request andMaintenance Plan base case had less error and less negative bias than the Revised 1999 CO Plan's, i.e., itunderpredicted by a smaller amount. The highest CO atany monitor in the MAG CO Redesignation Request andMaintenance Plan was about 2% above the peak observation, whereas in the Revised 1999 CO Plan, it was 10% or more below. In summary, the increased emissions in the MAG CO Redesignation Request andMaintenance Plan did in fact show up in the modeling results, but the effect was not to increase the highest peak, but rather
to increase concentrations more generally, distributed in time and space.

For microscale modeling with CAL3QHC, the same intersections asin the Revised 1999 CO Plan were used, 27th Ave./Grand/Thomas Rd. and 35th Ave./Grand/Indian School Road. Forthe attainment demonstration, the results of the CAL3QHC modeling were combined with that from UAMfor the cell containing the intersection, perEPA guidance. CAL3QHC contributions to peak concentrations was generally lower thanwas modeled for the Revised 1999 CO Plan.As discussed below, the decrease ispartly due to updated traffic data. A shiftin peak traffic to the morning occurred, which is further from the late-night CO peak. But the main

reason for decreased CAL3QHC predictions was the exclusion ofcold
start emissions from idling emissions at intersections, in accordance with EPA guidance. Most cold start emissions

occur within a few minutes oftrip starts, so they have little affect on intersection emissions. Despite generally higher UAM predictions inthe MAG CO Redesignation Request and Maintenance Plan, at the hotspot intersection locations, overall hotspot predictions are slightly lower. Table 3 lists the maximum combined dispersion modeling (UAM)and intersection modeling (CAL3QHC) results for the maintenance demonstration modeling at the West Indian School Road and Grand Avenue intersections (from MAG CO Redesignation Request and Maintenance Plan, page 3-13).

TABLE 3.-MAXIMUM DISPERSION MODELING AND INTERSECTION MODELING RESULTS [In parts per million]

2006 2015 Intersection UAM CAL3QHC Total UAM CAL3QHC Total

WISR1

.............................. . .... .... ..... ..... ..... ... ..... .... ..... ..... .. 7.17 1.08 8.25 6.23 1.81 8.04 Grand Ave

........................................................................ 7.74 0.50 8.24 7.16 0.65 7.81

1 West Indian School Road monitor.

The target CO concentration for the maintenance demonstration modeling is 9.0ppm. MAG therefore needed to show that combined UAM and CAL3QHC concentrations remain below 9 ppm in 2006 and 2015, despite the metropolitan area's growth. The MAG modeling shows a maximum CO concentration of 8.92 ppm in 2006, and 8.06 ppm in 2015; these meet the maintenance goal of9.0 ppm.

For episode selection, modeling domain, wind fields, initial and boundary conditions, sensitivity testing

was essentially identical between the
two episodes (see the EPATSD for the Revised 1999 CO Plan). The tests done showed thatthe model was responding reasonably. MAG's modeling alsomeets EPA's performance goals on peak level, peak timing, and absolute error. Model predictions in the MAG CO Redesignation Request andMaintenance Plan are closer to observations than in the Revised 1999 CO Plan modeling.
Since thepeak values andgeneral spatial patterns match well and EPA's model performance goals were met, overall the model appears to be replicating the episode fairly well, and forms an acceptable basis for a demonstration ofmaintenance. Overall, the modeling doneby MAG for the CO maintenance demonstration performed adequately and meets EPA guidelines. EPA proposes to find the maintenance demonstration approvable. 3.Monitoring Network and Verification ofContinued Attainment

Continued attainment ofthe CO NAAQS in the Maricopa County area depends, in part, on the State's efforts
to track indicators throughout the maintenance period. This requirement is met in two sections ofthe MAG CO Redesignation Request and Maintenance Plan. On page 3-15 ofthe MAG CO Redesignation Request and Maintenance Plan, MAG commits to continue the operation ofthe CO monitors in the Maricopa County area and to annually review this monitoring network and make changes as appropriate.

Also, onpage 3-15 ofthe MAG CO Redesignation Request and Maintenance Plan, MAG commits to track mobile

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largest component ofthe inventories) through the ongoing submittal of periodic emissions inventories every three years in accordance with section 187(a)(5) ofthe CAA. MCESD will coordinate and compile the inventory with input and assistance from ADEQ, the Arizona Department of Transportation, and MAG, as described in the 1992 Air Quality Memorandum of Agreement. Changes in the inventory will be reviewed and evaluated through the regional air quality planning process to determine ifadditional measures shouldbe considered.

Based onthe information above, we

are proposing approval ofthese commitments as satisfying the relevant requirements ofthe CAA for maintenance plans. We note that a final rulemaking approval will render the State's commitments federally enforceable.

4. Contingency Plan

Section 175A(d) ofthe CAArequires that a maintenance plan include contingency provisions. To meet this requirement, the State has identified appropriate contingency measures along with a schedule for the development and implementation of suchmeasures.

As stated on page 3-15 ofthe MAG CO Redesignation Request and Maintenance Plan, implementation of the contingency measures for the Maricopa County area willbe triggered by two verified readings exceeding 9.0
ppm at one monitor during a single CO

season (i.e.,October 1through March 31st). Since aviolation ofthe NAAQS for 8-hourCO occurs when the second highest reading at the same monitor

over two consecutive years is greater than or equal to 9.5 ppm, this triggeris

more stringent than the standard, and will serve to prevent the occurrence of future violations.

When the contingency measure trigger is activated, MAG will consider additional measures onthe following schedule: (a)Verification ofthe monitoring data to be completed three months after activation ofthe trigger; (b) applicable measure tobe considered for adoption six months after the date established in (a) above; and (c) the resultant measure to be implemented within six to twelve months, depending

onthe time needed to put the measure in place.

5.Commitment To Submit Subsequent Maintenance Plan Revisions

In accordance with section 175A(b) of the CAA, as the designated regional air quality planning agency for the Maricopa County area, MAG has committed to submit a revised maintenance plan eight years after redesignation. This provision for revising the maintenance plan is contained in Chapter 3, pages 3-16 to 3- 17 ofthe Maricopa County CO maintenance plan.

VII. EPA's Evaluation ofthe TransportationConformity Requirements in theMAG CO Redesignation Request and Maintenance Plan

One ofthe primary tests for conformity is to show that transportation plans andtransportation improvement programs will not cause motor vehicle emissions to increase above levels needed to make progress towards and tomeet air quality standards. The motor vehicle emissions levels needed to make progress toward andto meet the air quality standards are setin the area's air quality plans as "emissions budgets for motor vehicles". More details about conformity tests are described in section IV.A ofthis notice. EPA hasbeen using a process and specific criteria for determining the adequacy ofemissions budgets in control strategy SIPs since a 1999 court ruling. This process is now codified in

arecent revision to the conformity rule (see 69 FR 40004, July 1, 2004).

The MAG CO Redesignation Request andMaintenance Plan defines the CO
motor vehicle emissions budgets in the Maricopa County area as 699.7 tons per day for 2006 and 662.9 tons per day for 2015 and beyond. The budget for 2015 is equal tothe maintenance year (2015) mobile source emissions inventory for CO for the attainment/maintenance area. The MAG CO Redesignation Request andMaintenance Plan and supporting documentation indicate that the 662.9 budget for 2015 is consistent with maintenance ofthe CO NAAQS throughout the maintenance period. Therefore, we are proposing to approve the 699.7 tons per day CO emissions budget for 2006 andthe 662.9 tons per day CO emissions budget for 2015 for the Maricopa County nonattainment

area.

EPA's adequacy determination on the MAG CO budgets for 2006 and 2015 was made in aletter to ADEQ andMAG on September 9, 2003 and was announced in the Federal Register on September 29, 2003 (68 FR 55950). As a result of this adequacy finding, the 699.7 ton per day budget for 2006 and the 662.9 budget for 2015 took effect for the conformity determinations inthe Maricopa County nonattainment area on October 14, 2003. However, we are not bound by that determination in acting

onthe maintenance plan. VIII. GRICBoundary Change Under CAA Section 107

EPA isproposing to change the boundary ofthe Maricopa County CO nonattainment/maintenance area to exclude the Gila River Indian Reservation ("Reservation").

A. Background

1.Current Area Boundary, Designation, and Classification

Areas ofthe country were originally designated as attainment, nonattainment

or unclassifiable following enactment of the 1977 Amendments to the CAA. See 43 FR 8962 (March 3, 1978). These designations were generally based on monitored air quality values compared
to the applicable NAAQS. The Maricopa County nonattainment area was designated a nonattainment area for CO in April 1977. The boundary forthe Maricopa County CO nonattainment

area was first established following the CAA Amendments of 1977. See 43 FR 8962 (March 3, 1978)

Under the 1990 Clean Air Act Amendments, the Maricopa County CO nonattainment area was again classified

as a nonattainment area for CO. The nonattainment area boundary remained the same. 56 FR 6335 (November 6, 1991). On August 28, 1996, the Maricopa County CO nonattainment

area was reclassified to serious dueto a failure to attain the 8-hour CO standard by December 31, 1995. 61 FR 39345 (July 29, 1996)

Area boundaries and area classifications havebeen amended over the years under the applicable CAA provisions, either by request ofa state, by operation oflaw, orby EPA initiative. Forthe State ofArizona, the
current area designations and classifications are codified at 40 CFR 81.303.

2.GRIC's Request for a Boundary Change

OnJuly 14, 2004, the Gila River Indian Community ("Community"), a federally-recognized tribal government, 15 submitted aformal request to EPAto revise the boundary of the Maricopa County CO nonattainment

area to exclude the Reservation. 16The Community's analysis ofair quality data existing atthe time of and subsequent
to the designation in 1978 as well as the
nature ofthe CO sources onthe Reservation demonstrated thatthe Reservation has not had a monitored or

1567 FR46329 (July 12, 2002). 16The Maricopa County CO nonattainment area includes the portion ofthe Reservation that lies within Maricopa County, approximately the northern 25O%ofthe Reservation. 

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predicted violation ofthe CO NAAQS since, and thatno significant sources of CO exist on the Reservation.

B. EPAReview ofthe Community's Request

1.EPA's Authority to Change Boundaries

Under section 107(d)(3)(A), EPA has the authority to revise the boundary of

anonattainment area on thebasis of air quality data, planning and control considerations, or any other air qualityrelated considerations the Administrator deems appropriate.

2.The Gila River Indian Reservation Airshed

The Gila River Indian Reservation consists ofapproximately 374,000 acres in south central Arizona, south ofthe Phoenix metropolitan area. Currently, the Maricopa County (Phoenix area) CO nonattainment area includes the northern 92,000 acres ofthe Reservation. The Reservation is physically separated from the Phoenix metropolitan areaby the Sierra Estrella and SouthMountain Ranges. The Sierra Estrella Mountain Range runs north and south along the western edge ofthe Reservation. The SouthMountain Range

runs diagonally in a northeasterly direction, between one and five miles beyond the northern Reservation boundary. The mountain ranges act as a physical barrier between the two airsheds.

A segment ofthe northern border of the Reservation adjacent to Chandler does not have a topographical barrier to air pollution transport. However, the prevailing winds flow to the northeast, sending CO emissions from Chandler away from the Reservation. Along the northeastern border ofthe Reservation, the Santan Mountain Range separates the Reservation from Gilbert and Apache Junction.

The Reservation has a population of approximately 11,250 people, with a population density of approximately 20 people per square mile. There are no major population centers within the Reservation. By comparison, Maricopa County (including vast rural areas west ofthe urban area which are not part of the nonattainment area) has a population of2,122,101, with a population density ofover 230 people
per square mile.

3.CO and the Reservation

In general, ambient CO concentrations

are caused by onroad and nonroad mobile emissions sources. The level of mobile source emissions canbe directly correlated to population density and land use patterns. The Community population density of20 people per square mile is minor compared to all of Maricopa County, which has a density ofover 230 people per square mile. Commuting patterns onthe Reservation

are virtually nonexistent. Approximately 2200 cars, trucks and

vans commute to work within the Reservation, compared to 1,250,000 in Maricopa County. There is little economic integration with commercial development in metropolitan Phoenix, andthe Reservation remains largely rural and agricultural. The Community plans to expand its agricultural base by investing millions ofdollars in agricultural infrastructure.

Total annual emissions ofCO on the Reservation areless than one percent of those in the MAG serious CO nonattainment area. High CO concentrations in the MAG nonattainment area are associated almost exclusively with areas ofhigh traffic congestion, which donot exist on the Reservation. Therefore, there is substantial basis for concluding thatthe Reservation is an insignificant generator ofCO emissions.
4. CO Planning Issues

Attainment ofthe CO NAAQS in the Phoenix metropolitan area was achieved by Arizona through the SIP planning
process. It is important to note that, under the Clean Air Act, the state and local airpollution control authorities

are not administering EPA-approved air regulatory programs over the Reservation; consequently, the SIP rules that were appliedto the metropolitan

area and resulted in attainment ofthe NAAQS did not apply tothe Reservation. Furthermore, due tothe Reservation's lack ofCO sources, it was

never considered necessary to apply CO limits to sources in the Reservation. 1 7

Just asit was clear thatit was not necessary for an attainment plan to be applicable tothe Reservation for the Phoenix area to attain the CO NAAQS, it is clear toEPA thatit will notbe
necessary for a maintenance plan to be applicable tothe Reservation for the Phoenix area to maintain attainment of the NAAQS.

C.RedesignationoftheNorthern PortionoftheReservation

In view ofthe above considerations, andbecause no CO air quality data exists for the Reservation, EPA believes "nonclassifiable/attainment" isthe

17EPA could have applied CO limits to sources

on the Reservation, as ithas authority under CAA 301(d) to promulgate regulations for Indian country

as necessary or appropriate "to achieve the appropriate purpose" ofthe Act. appropriate designation for the entire Reservation, including thatportion heretofore included inthe nonattainment area. Therefore, EPA proposes to redesignate to "nonclassifiable/attainment" the portion ofthe Reservation thatis now within the nonattainment area, and make itpart ofthe surrounding nonclassifiable/attainment area.
IX.Proposed Action

We are solicitingpublic comment on all aspects ofthis proposed SIP rulemaking action. We will consider
your comments in deciding our final action ifyour comments are received by November 8, 2004.

We propose to approve the following elements ofthe Revised 1999 CO Plan for the metropolitan Phoenix area and the MAG CO Redesignation Request and Maintenance Plan:

1. 1990 base year and 1993 and 1996 periodic emission inventories as required by sections 172(c)(3) and 187(a)(5).

2. Demonstration thatthe plan provides for the implementation of reasonably available control measures including transportation control

measures under sections 172(c)(1) and 187(b)(2);

3. Demonstration of attainment by December 31, 2000 under section 187(a)(7);

4. Demonstration ofreasonable further
progress under sections 172(c)(2) and 187(a)(7);

5. Contingency measures under sections 172(c)(9) and 187(a)(3);

6. Forecasts ofvehicle miles traveled and provisions for annual tracking and reporting under section 187(a)(2)(A);

7.Transportation control measures as necessary to offset growth in emissions under section 187(b)(2);

8. Attainment year and projected emissions inventories under section 175A;

9. Air quality monitoring requirements under section 110(a)(2) and section 172(c)(7);

10. CO motor vehicle emissions budgets for transportation conformity under section 176(c) for the attainment demonstration and the maintenance planfor the years 2000, 2006 and 2015 underthe transportation conformity rule, 40 CFR Part 93, subpart A;

11. Demonstration ofmaintenance under section 175A(a) and afullyapproved maintenance planunder section 175A;

12. Maintenance plan contingency

measures under section 175A(d);

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14. Redesignation ofthatportion of the Gila River Indian Reservation that is

now within the nonattainment area to "nonclassifiable/attainment'; and

15. A determination thatthe improvement in air quality in the Maricopa County nonattainment area is dueto permanent and enforceable reductions in emissions resulting from the implementation ofthe applicable implementation plan, implementation ofapplicable Federal airpollution control regulations, and other permanent and enforceable reductions.

We have previously approved all control measures relied on for attainment and contingency measures in the Revised 1999 CO Plan, including the area's enhanced inspection and maintenance program (required by section 187(a)(6)), oxygenated gasoline program (requiredby sections 187(b)(3) and 211(m)), and woodburning curtailment regulations. See 68 FR 2912, 69 FR 10161, 64 FR 60678 and 67 FR 52416.

As stated above, we are proposing approval ofMAG's June 16, 2003 request to redesignate the Maricopa County CO nonattainment area to attainment and proposing approval of the maintenance plan for the Maricopa County CO nonattainment area.

We are also proposing to change the designation ofthe portion ofthe Gila River Indian Community which is in the Maricopa County CO nonattainment

area to "unclassifiable/attainment" for CO.

X. Statutoryand Executive Order Reviews

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this proposed action is not a "significant regulatory action" and therefore is not subject to review bythe Office ofManagement and Budget. For this reason, this action is also not subject toExecutive Order 13211, "Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, orUse" (66 FR 28355, May 22, 2001). This proposed action merely
proposes to approve state law as meeting Federal requirements and imposes no additional requirements beyond those imposedby state law. Accordingly, the Administrator certifies that this proposed rule will not have a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.).Because this rule
proposes to approve pre-existing requirements under state law and does
not impose any additional enforceable dutybeyond thatrequired by state law, it does not contain any unfunded mandate or significantly oruniquely affect small governments, as described in the Unfunded Mandates Reform Act of1995 (PublicLaw 104-4).

Executive Order 13175, entitled "Consultation and Coordination with Indian Tribal Governments" (65 FR 67249, November 6, 2000), requires EPA
to develop an accountable process to

ensure "meaningful and timely inputby tribal officials in the development of regulatory policies thathave tribal implications." "Policies that have tribal implications" is defined in the Executive Order toinclude regulations that have "substantial direct effects on

one or more Indian tribes, on the relationship between the Federal government and the Indian tribes, or on the distribution ofpower and responsibilities between the Federal government and Indian tribes."

Under section 5(b) ofExecutive Order 13175, EPA may not issue aregulation that has tribal implications, that imposes substantial direct compliance costs, and thatis not required by statute, unless the Federal government provides the funds necessary to paythe direct compliance costs incurred bytribal governments, orEPA consults with tribal officials early in the process of developing the proposed regulation. Under section 5(c) ofExecutive Order 13175, EPA may not issue aregulation that has tribal implications and that preempts tribal law, unless the Agency consults with tribal officials early in the
process ofdeveloping the proposed regulation.

EPA has concluded that this proposed rule may have tribal implications. EPA's action will remove the Gila River Indian Community from the Phoenix CO maintenance area. However, itwill neither impose substantial direct compliance costs on tribal governments,

nor preempt State law. Thus, the requirements ofsections 5(b) and 5(c) of the Executive Order donot apply to this rule.

Consistent with EPApolicy, EPA nonetheless consulted with representatives oftribal governments early in the process ofdeveloping this regulation topermit them tohave meaningful and timely input into its development. Representatives oftribal governments approached EPAtwo years ago and requested that EPAmake this boundary change. We agree with the technical and policyrationale the tribe provided, and believe that alltribal

concerns have been met.

In the spirit ofExecutive Order 13175, and consistent with EPA policy to promote communications between EPA andtribal governments, EPA specifically solicits additional comment on this proposed rule fromtribal officials.

This action also does not have Federalism implications because itdoes
nothave substantial direct effects onthe States, on the relationship between the national government andthe States, or

on the distribution ofpower and responsibilities among the various levels ofgovernment, as specified in Executive Order 13132 (64 FR 43255, August 10, 1999). This action merely
proposes to approve a state rule implementing a Federal standard, and does not alter the relationship or the distribution ofpower and responsibilities established in the Clean AirAct. This proposed rule also isnot subject to Executive Order 13045 "Protection ofChildren from Environmental HealthRisks and Safety Risks" (62FR 19885, April 23, 1997), because itis not economically significant.

In reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the Clean Air Act. In this context, in the absence ofa prior existing requirement for the State touse voluntary consensus standards (VCS), EPA has no authority
to disapprove a SIP submission for failure to use VCS. Itwould thus be inconsistent with applicable law for EPA, when itreviews a SIP submission,
to use VCS in place ofa SIP submission that otherwise satisfies the provisions of the Clean Air Act. Thus, the requirements ofsection 12(d) ofthe National Technology Transfer and Advancement Act of1995 (15 U.S.C. 272 note) do not apply. This proposed rule does not impose an information collection burden under the provisions ofthe Paperwork Reduction Act of 1995 (44 U.S.C. 3501 etseq.).

List ofSubjects

40 CFRPart52

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

40 CFRPart81

Air pollution control, National parks, Wilderness areas.

Dated: September 21, 2004. Laura Yoshii, ActingRegional Administrator,Region9. [FR Doc. 04-22485 Filed 10-7-04; 8:45 am]

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