[Federal Register Volume 69, Number 159 (Friday, October 8, 2004)]
[Proposed Rules]
[Pages 60328-60343]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-22485]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[AZ104-0069; FRL-7823-6]


Approval and Promulgation of Implementation Plans and Designation 
of Areas for Air Quality Planning Purposes; Arizona

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing 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 
proposing to approve the MAG CO redesignation request and maintenance 
plan for the Maricopa County CO nonattainment area as meeting CAA 
requirements for redesignation requests and maintenance plans. In 
addition, we are proposing to make a boundary change under Section 107 
of the CAA to take the Gila River Indian Community (GRIC) out of the 
Maricopa County maintenance area. The portion of the Gila River Indian 
Community which is currently in the Maricopa County CO nonattainment 
area will be ``unclassifiable/attainment'' for CO, and will not be 
subject to the 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 should be mailed or emailed to 
Wienke Tax, Office of Air Planning (AIR-2), U.S. Environmental 
Protection Agency, Region 9, 75 Hawthorne Street, San Francisco, CA 
94105-3901, [email protected]. Comments may also be submitted through 
the Federal Register Web site at http://www.regulations.gov. We prefer 
electronic comments.
    You can inspect copies of EPA'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 that we can make arrangements to have someone meet you. The 
Federal Register document and TSD are also available as electronic 
files on EPA's

[[Page 60329]]

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, Air Division, Air 
Planning Office (AIR-2), 75 Hawthorne Street, San Francisco, CA 
94105.

    Copies of the SIP materials are also available for inspection at 
the address listed below:
    Arizona Department of Environmental Quality, 1110 W. Washington 
Street, First Floor, Phoenix, AZ 85007, Phone: (602) 771-4335.

FOR FURTHER INFORMATION CONTACT: Wienke Tax, Office of Air Planning, 
U.S. Environmental Protection Agency, Region 9, (520) 622-1622, e-mail: 
[email protected], or http://www.epa.gov/region09/air.

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

Table of Contents

I. Summary of Today's Proposed Action
II. The Serious Area CO SIP for the Phoenix Area
III. The CAA's Requirements for Serious CO Nonattainment Area Plans
IV. The Revised 1999 CO Plan's Compliance With the CAA's 
Requirements for Serious CO Nonattainment Area Plans
    A. Completeness of the SIP Submittals and Adequacy of the Motor 
Vehicle Emissions Budget
    B. Emissions Inventory
    C. Adequate Monitoring Network
    D. Implementation of Reasonably Available Control Measures
    E. Demonstration of Attainment
    F. Reasonable Further Progress
    G. VMT Tracking and Reporting
    H. Transportation Control Measures To Offset Growth in Emissions
    I. Contingency Measures
    J. Enhanced I/M Program
    K. Wintertime Oxygenated Gasoline Program
    L. General SIP Requirements
V. The CAA's Requirements for Serious CO Maintenance Plans and 
Redesignation Requests
VI. The MAG CO Redesignation Request and Maintenance Plan's 
Compliance With the CAA's Requirements for CO Redesignation Requests 
and Maintenance Plans
    A. General SIP Requirements
    B. Attainment of the CO NAAQS
    C. Meeting Applicable Requirements of Section 110 and Part D
    D. Fully-Approved SIP Under Section 110(k) of the CAA (NSR)
    E. Improvement in Air Quality Due to Permanent and Enforceable 
Measures
    F. Fully-Approved Maintenance Plan Under Section 175A
VII. EPA's Evaluation of the 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 of the Community's Request
    C. Redesignation of the Northern Portion of the Reservation
IX. Proposed Action
X. Statutory and Executive Order Reviews

I. Summary of Today's Proposed Action

    We are proposing to approve the MAG serious area SIP for attainment 
of the 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 also proposing to approve the MAG CO redesignation request 
and maintenance plan for the Maricopa County CO nonattainment area as 
meeting CAA requirements for redesignation requests and maintenance 
plans.
    We are also proposing to make a boundary correction under Section 
107 of the CAA for the Gila River Indian Community.

II. The Serious Area CO SIP for the Phoenix Area

    We are proposing to approve the Revised MAG 1999 Serious Area 
Carbon Monoxide Plan for the Maricopa County Nonattainment Area, 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 a revision to the Arizona SIP on 
March 30, 2001 and EPA received it on April 2, 2001. We refer to this 
plan in this document as the Revised CO Plan or the Revised 1999 CO 
plan, or variations of these.
    As submitted, the Revised 1999 CO plan consists of the main plan 
document, three volumes of technical appendices and three volumes of 
commitments from various 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. It uses the Urban Airshed Model (UAM) and CAL3QHC microscale 
model to model air quality in 1994 as a base year and in 2000 as the 
attainment year and demonstrates both reasonable further progress 
towards and attainment of the CO standard by December 31, 2000.
    The MAG plan shows that the 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 also previously approved the commitments by the 
Phoenix area cities and towns to adopt and/or implement CO control 
measures. We approved these commitments as part of the serious area PM-
10 plan approval on July 25, 2002 at 67 FR 48718. See 40 CFR 
52.120(c)(100). Many of these commitments by Phoenix area cites and 
towns commit to measures which address CO as well as PM-10 emissions 
reductions.
    For a complete history of the CO planning efforts in the Phoenix 
area as well as the history of the development of the CO plan, please 
see Section 1 in EPA's TSD.

III. The CAA's Requirements for Serious CO Nonattainment Area Plans

    The Phoenix area was reclassified from moderate to serious for CO 
on July 29, 1996 (61 FR 39343) because the area had not attained the CO 
standard by the moderate area deadline of December 31, 1995. As a 
result of this reclassification, Arizona was required to submit by 
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 by December 31, 2000. In summary, these 
requirements are:
    (a) Implementation of all reasonably 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 that the plan 
will provide for attainment by no later than December 31, 2000 (CAA 
section 187(b)(7));
    (c) Provisions for such specific annual emission reductions as are 
necessary to attain by December 31, 2000 (CAA sections 172(c)(2) and 
187(b)(7));

[[Page 60330]]

    (d) Forecasts of vehicle miles traveled (VMT) in the nonattainment 
area for each year before the year in which the plan projects 
attainment (CAA section 187(a)(2)(A));
    (e) An enhanced vehicle inspection and maintenance program (CAA 
section 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 from vehicle miles traveled or numbers of vehicle 
trips (CAA section 187(b)(2));
    (h) Contingency measures that will be implemented if the area fails 
to attain by 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) A comprehensive, accurate, current inventory of actual 
emissions from all sources of CO (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 that the 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 as required by 40 CFR 51.111.\1\
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    \1\ Serious area SIPs must also include new source review (NSR) 
permitting rules that meet the requirements of sections 172(c)(5) 
and 173. In practice, NSR rules are submitted and reviewed 
separately from the rest of the serious area CO plan. Maricopa 
County has submitted a complete NSR rule.
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    We have issued a General Preamble \2\ describing our preliminary 
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 of those SIPs, 
including the ``Technical Support Document to Aid States with the 
Development of Carbon Monoxide State Implementation Plans,'' Office of 
Air Quality Planning and Standards (OAQPS), U.S. EPA, EPA-452/R-92-003 
(July 1992).
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    \2\ ``State Implementation Plans; General Preamble for the 
Implementation of Title I of the Clean Air Act Amendments of 1990,'' 
57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28, 1992).
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    On July 8, 1999, ADEQ submitted the MAG 1999 Serious Area CO Plan 
(``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 House Bill (HB) 2104 during the 2000 regular session, which 
repealed the remote sensing portion of the VEI program. We indicated 
that the 1999 CO Plan would need to be revised to reflect the change in 
the VEI program. MAG conducted new air quality modeling and revised the 
1999 CO Plan. On April 2, 2001, ADEQ submitted the Revised 1999 MAG 
Serious Area CO Plan (``Revised 1999 CO Plan'') to EPA.

IV. The Revised 1999 CO Plan's Compliance With the CAA's Requirements 
for Serious CO Nonattainment Area Plans

    The following sections present a summary of our evaluation of the 
Revised 1999 CO Plan's compliance with the applicable CAA requirements 
for serious area SIPs for CO. Our complete evaluation is found in the 
EPA TSD for this action.\3\ A copy of the EPA TSD can be obtained by 
calling or writing the contact person listed above.
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    \3\ See ``Technical Support Document for the Notice of Proposed 
Rulemaking on the Carbon Monoxide Serious Area Planning Requirements 
for the Maricopa County, Arizona Nonattainment Area,'' June 2004, 
Air Division, USEPA Region 9.
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A. Completeness of the SIP Submittals and Adequacy of the Motor Vehicle 
Emissions Budget

    The first step we take after receiving a SIP submittal is to 
determine if it is complete. CAA section 110(k)(1)(B) requires that we 
review all SIPs and SIP revisions for completeness within 60 days of 
receipt. The completeness review allows us to quickly determine if the 
submittal includes all the necessary items and information we need to 
take action on it. 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 on April 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 of the EPA TSD.
    Section 176(c) of the Clean Air Act requires that federally funded 
or approved transportation plans, programs, and projects in 
nonattainment areas ``conform'' to the area's air quality SIPs. 
Conformity ensures that federal transportation actions do not worsen an 
area's air quality or interfere with its meeting the air quality 
standards. We have issued a conformity rule that establishes the 
criteria and procedures for determining whether or not transportation 
plans, programs, and projects conform. See 40 CFR part 93, subpart A.
    One of the 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 and to meet the air quality standards. The motor vehicle 
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's policy on emissions budgets are found in the 
preamble to the November 24, 1993 transportation conformity rule (58 FR 
62193-96), in the sections of the rule referenced above, and in 
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 
a revised mobile source emissions budget of 412.2 metric tons per day 
(mtpd). Revised 1999 CO Plan, p. 9-11. We found this budget adequate 
for transportation conformity purposes on September 28, 2001. See 
letter, Jack Broadbent, EPA Region 9 to Jacqueline Schafer, ADEQ, and 
James Bourey, MAG. Our finding was published in the Federal Register on 
October 17, 2001 (66 FR 52761) and became effective 15 days later on 
November 1, 2001.

B. Emissions Inventory

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

[[Page 60331]]

modeling inventory were conducted. MAG subsequently revised the nonroad 
equipment modeling assumptions to be 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 (both 
point 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 of 
particular sources. Seasonal inventories are provided to account for 
the differences in emissions occurring during the times of year when 
Maricopa County used to exceed the 8-hour CO standard. We are approving 
the emission inventories of the Maricopa County CO nonattainment area 
as meeting the requirements of section 172(c)(3) of the CAA.
    On September 18, 1996, we proposed approval of the 1990 base year 
CO emissions inventory for Maricopa County (see 61 FR 49087). When we 
finalize today's proposed action, we will also finalize approval of the 
1990 base year emissions inventory proposed on September 18, 1996.

C. Adequate Monitoring Network

    The CAA requires states to establish and operate air monitoring 
networks to compile data on ambient 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 to measure ambient concentrations of CO, 
including measurement method requirements, network design, quality 
assurance procedures, and in the case of large urban areas, the minimum 
number of monitoring sites designated as National Air Monitoring 
Stations (NAMS).
    Ambient networks, however, do not need to meet all our regulations 
to be 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 of 
the Clean Air Act are not generally required to address how the area's 
air quality network meets our monitoring regulations. These plans are 
submitted too infrequently to serve as the vehicle for assuring that 
monitoring networks remain current.
    For this action, we are discussing the adequacy of the Phoenix area 
monitoring network solely to support our finding that the Revised 1999 
CO Plan appropriately evaluates the CO problem in the Phoenix area. 
Reliable ambient data is 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 by the Maricopa County Environmental 
Services Department and one by ADEQ. Figure 4-3 on page 4-7 in the 
Revised 1999 CO Plan lists the names of the sites and their locations 
in the Phoenix area. These sites all use EPA reference methods, are 
sited according to our regulations, meet the applicable monitoring 
objections in our regulations, and are operated according to our 
regulations. We therefore find that the monitoring network operated by 
the MCESD and ADEQ is adequate to support the technical evaluation of 
CO nonattainment problem in the Revised 1999 CO Plan. See also EPA TSD 
section ``Ambient Air Quality Surveillance''.

D. Implementation of Reasonably Available Control Measures

    CAA section 172(c)(1) requires that nonattainment plans provide for 
the implementation of all reasonably available control measures (RACM) 
as expeditiously as practicable. 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 of the area's attainment 
demonstration. In general, we do not consider a measure to be 
reasonably available if it is economically or technologically 
infeasible for the area, would not advance attainment of the relevant 
standard in the area, or is absurd, unenforceable or impracticable. 
General Preamble at 13560.
    As described above, the principal sources of CO 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 of the 1996 seasonal inventory. Revised 1999 CO Plan, 
Figure ES-2. The Revised 1999 CO Plan evaluates a broad range of 
controls for each of these 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 and incentives for the use of alternative fueled 
vehicles, and numerous transportation control measures (TCMs). See 
Revised 1999 CO Plan, Chapter 8. We find that these measures along with 
the federal motor vehicle tailpipe standards provide a comprehensive 
control strategy for attaining the CO standard and provide for the 
implementation of RACM in the on-road motor vehicle category as 
required by CAA section 172(c)(1). See EPA TSD 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 such measures as necessary to demonstrate attainment. The 
Phoenix area has a long history of adopting TCMs, including those in 
section 108(f), for controlling CO. The Revised 1999 CO Plan implements 
the section 108(f) TCMs and includes additional measures in support of 
the attainment demonstration. See Revised 1999 CO Plan, Table 7-2 and 
Chapter 8. We therefore find that the Revised 1999 CO Plan complies 
with CAA section 187(b)(2) and 172(c)(1). See EPA TSD section 
``Implementation of RACM for On-Road Motor Vehicle Controls--
Transportation Control Measures.''
    The nonroad (mobile) engine category covers a diverse collection of 
engines, 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 for nonroad engines, ninety percent of CO emissions 
from the nonroad category come from gasoline-powered nonroad engines.
    Starting in the mid-1990s, EPA promulgated national emission 
standards for a broad range of nonroad engines. See EPA TSD section 
``Implementation of RACM for Nonroad Engines.'' Nonroad engines sold in 
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 CBG program regulates gasoline used in 
nonroad engines. The Revised 1999 CO Plan also includes a number of 
other nonroad engine measures. See EPA TSD section ``Implementation of 
RACM for Nonroad Engines.'' With the national emission standards and 
the additional State

[[Page 60332]]

measures, we find that the Revised 1999 CO Plan provides for the 
implementation of RACM for nonroad engines.
    The residential wood combustion (RWC) category includes emissions 
from the burning of solid fuel in residential fireplaces and woodstoves 
as well as barbecues and fire pits. Measures to control CO from 
residential woodburning include a public education program, woodburning 
curtailment programs, retrofit requirements and restrictions or bans on 
the installation of woodburning stoves and/or fireplaces.
    The Maricopa County Environmental Services Department's Rule 318, 
Approval of Residential Woodburning Devices, establishes standards for 
the approval of residential 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/or the PM 
standard (150 [mu]g/m3). We approved Rule 318 and an earlier 
version of the ordinance (revised April 21, 1999) as providing for the 
implementation of RACM. See 64 FR 60678 (November 8, 1999).
    The Revised 1999 CO Plan includes a number of other woodburning 
measures. We find that these measures along with Maricopa County's 
woodburning rules provide for the implementation of RACM for 
residential wood combustion. See EPA TSD section ``Implementation of 
RACM for Residential Wood Combustion.''

E. Demonstration of Attainment

    CAA section 187(a)(7) requires serious area plans to provide for 
attainment of the CO NAAQS by December 31, 2000 and to contain a 
demonstration that the plan will provide for attainment. Under our 
guidance, an attainment demonstration may be made using EPA-approved 
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 of the modeling 
itself, and (2) evaluating the control measures that are relied on to 
demonstrate attainment. We discuss each part below.
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 of control measures 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 of the simulation and every one square mile grid cell 
requires these inputs. Diagnostic testing is performed to ensure the 
model is performing well for a chosen CO episode, which in this case 
was December 17, 1994, which at 10.5 ppm had the highest CO peak and 
most widespread high CO readings observed during 1994. Once the model 
predicts observed CO concentrations for this chosen CO episode 
adequately, post-control 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 to the 
level of the NAAQS, 9.0 ppm, to demonstrate attainment.
    As detailed in the TSD, MAG followed accepted procedures in 
developing the model inputs, performing diagnostic testing of the 
results, and showing adequate model performance. Model performance 
statistics met EPA-recommended goals. The observed spatial and temporal 
patterns of CO were replicated fairly well by the model. While there 
were some discrepancies, these were attributed to lack of observations 
at some locations, and by slight shifts in wind patterns. That is, if 
the wind field input to the model had been 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 by MAG meets EPA guidelines and performs 
well enough to be relied upon as the 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 of the 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, intelligent transportation systems, and deferring 
emissions associated with government activities. See Revised 1999 CO 
Plan, Figure 9-1. We have previously approved all of these measures. 
See 68 FR 2912, 69 FR 10161, 64 FR 60678, and 67 FR 48718.
    As part of these approvals, we have evaluated each of these 
measures to ensure that they meet our SIP enforceability criteria. 
These criteria ensure that the 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 that the 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 that the measures relied on for attainment are being 
expeditiously implemented. See EPA TSD, section ``Attainment 
Demonstration''.

F. Reasonable Further 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 of the relevant 
air pollutant as are required by this part [part D of title I] or may 
reasonably be required by the Administrator for the purpose of ensuring 
attainment of the applicable national ambient air quality standard by 
the applicable date.'' For serious CO nonattainment areas, CAA section 
187(a)(7) also requires the plans to provide for such specific annual 
emission reductions as are necessary to attain the standard by the 
applicable attainment date.
    We find that the Revised 1999 CO Plan provides for RFP and for such 
specific annual emission reductions as are necessary to attain the 
standard by the December 31, 2000 as required by the Act.\4\ The 
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 
CBG programs) were implemented, and 2000 is the attainment year. Total 
design day CO emissions drop from 687 mtpd

[[Page 60333]]

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 II-4.
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    \4\ This 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).
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G. VMT Tracking and Reporting

    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 EPA in consultation with the U.S. 
Department of Transportation. This section also requires the plan to 
provide for annual updates of the forecasts to be submitted along with 
a report containing estimates of actual VMT for the year. We provided 
detailed guidance to States regarding the VMT tracking and reporting 
requirement in ``Section 187 VMT Forecasting and Tracking Guidance,'' 
USEPA, January 1992.
    We find that the 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 
on Highway Performance Monitoring System (HPMS) traffic counts adjusted 
in a reasonable manner to cover the 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 and Tracking Report,'' MAG, September 22, 1999 
(submitted September 23, 1999); ``2000 Vehicle Miles Travel Forecasting 
and Tracking Report,'' MAG, September 11, 2000 (submitted September 21, 
2000); and ``2001 Vehicle Miles Travel Forecasting and Tracking 
Report,'' MAG, October 23, 2001 (submitted November 14, 2001).

H. Transportation Control Measures To Offset Growth in Emissions

    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 and 
numbers of trips'' and to achieve reductions in mobile source emissions 
as necessary in conjunction with other measures to comply with the 
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 
motor vehicle 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 of 1994 until the attainment year of 2000 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 of the CO standard. Therefore, we propose to 
find that the Revised 1999 CO Plan meets CAA section 187(b)(2).

I. Contingency Measures

    CAA section 172(c)(9) requires that nonattainment area SIPs provide 
for the implementation of specific measures to be undertaken if the 
area fails to make RFP or attain by its attainment deadline. CAA 
section 187(a)(7) requires that serious CO nonattainment area plans 
also contain contingency measures that would be implemented if the area 
exceeds its vehicle mile traveled (VMT) projections. Both sections 
require that these contingency measures are to take effect without 
further action by the State or the Administrator. The Act does not 
specify how many contingency measures are necessary nor does it specify 
the magnitude of the emission reductions (or VMT reductions) they must 
produce. In policy and in previous rulemaking we have suggested that 
one appropriate choice of contingency measures would be to provide for 
the implementation of sufficient VMT reductions or emissions reductions 
to counteract the effect of one year's growth in VMT in order to ensure 
continued progress while the plan was being revised to correct any 
deficiencies that resulted in a failure to attain, make RFP, or keep 
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 or 
RFP demonstrations. This approach effectively allows for the early 
implementation of contingency measures.\5\
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    \5\ See memorandum, G. T. Helms, Chief, Ozone/Carbon Monoxide 
Programs Brand, OAQPS to Air Branch Chiefs, Regions I-X, ``Early 
Implementation of Contingency Measures for Ozone and Carbon Monoxide 
(CO) Nonattainment Areas,'' August 13, 1993 (``Helms memo'').
---------------------------------------------------------------------------

    The Revised 1999 CO Plan includes 9 contingency measures, all of 
which 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 of the largest categories of CO 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 of 
714.9 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) 
of the 2000 base case inventory.
    One of the eight contingency measures listed in the Revised 1999 CO 
Plan is no longer applicable. Funding for the lawn mower reduction 
program ended in FY 2001. Prior to 2001, the program resulted in the 
retirement of a large number of gasoline-powered commercial and 
residential lawn mowers and other hand-held gasoline-powered 
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.
---------------------------------------------------------------------------

    \6\ In 1998/99, the program retired 1780 old, polluting gas 
mowers and 563 other pieces of garden equipment. See ``Current 
Status of Carbon Monoxide,'' Maricopa County Environmental Services 
Department, (January 2000).
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    The use of an 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

[[Page 60334]]

in an area while its SIP is being revised to correct for a failure to 
attain or to make RFP or to deal with higher than expected VMT growth. 
To the extent that federal programs provide for this continued progress 
and the State has not otherwise relied on the program to demonstrate 
attainment or RFP, the State may rely on that measure.\7\
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    \7\ However, if the federal program is delayed or does not 
generate the expected emission reductions, the State would have to 
revise its contingency measures to assure adequate emission 
reductions or face a finding of SIP inadequacy.
---------------------------------------------------------------------------

    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 EPA policy and meet the statutory 
requirement that they ``take effect without further action by the State 
or the Administrator,'' we propose to find that the 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. Enhanced I/M Program

    CAA section 187(b)(6) requires that all serious CO nonattainment 
areas implement an enhanced I/M program 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. For more information on the requirements for enhanced I/M 
programs, 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 of revisions to Arizona's enhanced and basic I/M 
program).
    Arizona first submitted the legislation and regulations for the 
Maricopa County enhanced vehicle emission inspection program in 1994 as 
part of its moderate area plans for CO and ozone. Subsequently, Arizona 
made a number of modifications to its program including revising the 
testing protocol, requiring on-board diagnostic system testing, 
expanding the exemption to the latest five model years, changing the 
waiver provisions, and removing the remote sensing element of the 
program. The State resubmitted the program for approval in 2001. See 
2001 I/M submittal.
    In a separate action, we approved Arizona's vehicle emission 
inspection program for the Phoenix area as meeting the enhanced I/M 
program requirements of CAA section 187(b)(6) and our regulations. See 
68 FR 2912 (January 22, 2003).

K. Wintertime Oxygenated Gasoline Program

    CAA section 211(m) requires states with CO nonattainment areas with 
design values of 9.5 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 
Sec.  187(b)(3). Under both 211(m) and 187(b)(3), the program is to 
apply to all gasoline sold, supplied, offered for sale or supply, 
dispensed, transported or introduced into commerce in the consolidated 
metropolitan statistical area (CMSA) or, if no CMSA exists, the 
metropolitan statistical area (MSA).
1. History of State Program
    Arizona first adopted a wintertime oxygenated gasoline program in 
1988, before sections 187(b) and 211(m) were added to the Act as part 
of the 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, it required leaded gasoline to contain 
between 2.4 and 3.7 percent oxygen by weight and unleaded gasoline to 
contain between 1.9 and 3.7 percent oxygen by 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) and would, 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 of Appeals in Delaney v. EPA, 898 F.2d 687 (9th Cir. 
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 its place, EPA 
adopted a FIP with an oxygenated gasoline program. EPA modeled the FIP 
program on the then newly adopted requirements in 211(m). It required 
all gasoline sold in the Maricopa nonattainment area to contain a 
minimum oxygen content of 2.7 percent by weight from October 1 to March 
31 of each year. In the FIP notice, we noted that section 211(m) added 
by the 1990 Clean Air Amendments would require Maricopa to adopt a 
similar state requirement beginning in 1992. As a result, we 
anticipated that the 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 less than 2.7 percent oxygen by 
weight from September 30 to March 31 of each year. In that approval, 
EPA noted that the area covered by the program did not include the 
entire MSA as required under section 211(m). Instead, the program 
applied only to the Maricopa CO nonattainment area, which was then 
defined as the MAG urban planning area. As a result, we found the State 
program could be approved into the SIP as an equivalent substitution 
for the FIP program but concluded that Arizona would need to modify the 
program further by November 1, 1992 in order to meet all the 
requirements of 211(m). Id.
    Since our March 1992 approval, Arizona has made a number of changes 
to the wintertime oxygenated gasoline program. In 1998, EPA approved 
changes to the wintertime program as part of our approval of the 
State's new Cleaner Burning Gasoline (CBG) program. 63 FR 6653 (Feb. 
10, 1998). The wintertime program approved at that time 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 1 through March 31. In our approval, we 
did not address compliance with 211(m), instead finding the revisions 
necessary for attainment of the ozone and PM-10 NAAQS.
---------------------------------------------------------------------------

    \8\ The revised rules established new defined ``areas'' for 
specifying the applicability of their 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 of changes to the 
definition of Area A to affect the applicability of the fuel 
requirements.
---------------------------------------------------------------------------

    On March 4, 2004, we approved into the SIP further revisions to the 
State CBG program, including changes to the wintertime oxygenated 
gasoline

[[Page 60335]]

requirements. 69 FR 10161. The current SIP-approved wintertime program 
requires all gasoline sold in Maricopa County and in parts of Pinal and 
Yavapai Counties from November 1 to 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 to the covered area that have been approved 
into the SIP (i.e., the inclusion of portions of Yavapai and Pinal 
Counties) do not correspond to the entire MSA, which itself has been 
subsequently modified by the Census Bureau.\9\
---------------------------------------------------------------------------

    \9\ All of Pinal County was added to the definition of the 
Phoenix-Mesa MSA by the 1990 census.
---------------------------------------------------------------------------

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 of the CO standard 
since 1997, when the program was initiated. As a result, we are 
proposing to find that further changes to the program to meet the 
specific requirements of 211(m), including the requirement that the 
program apply to the entire MSA, are not required under the Act.
    Section 211(m)(6) provides:

    Nothing in this subsection shall be interpreted as requiring an 
oxygenated gasoline program in an area which is in attainment for 
carbon monoxide, except that in a carbon monoxide nonattainment area 
which is redesignated as attainment for carbon monoxide, the 
requirements of this subsection shall remain in effect to the extent 
such program is necessary to maintain such standard thereafter in 
the area.

    See also CAA section 187(b)(3)(B) (providing that a wintertime 
oxygenated program is not required for an area if the State 
demonstrates that the revision is not necessary for attainment and 
maintenance of the CO NAAQS). We have interpreted this language to mean 
that once EPA determines that a CO nonattainment area is actually 
attaining the CO NAAQS and the area demonstrates it does not need a 
program meeting 211(m), section 211(m) no longer requires submittal of 
a 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 of the Camden, New Jersey area).
    Today's finding that the State need not submit a program complying 
with section 211(m) does not mean the State 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(l).

L. General SIP Requirements

    CAA section 110(a)(2)(C) requires SIPs to include a program to 
provide for the enforcement of SIP measures. Section 110(a)(2)(E)(i) 
requires that SIPs provide necessary assurances that the State (or the 
general purpose local government) will have adequate personnel, funding 
and authority under State law to implement the submitted SIP. Finally, 
section 110(a)(2)(E)(iii) requires SIPs to include necessary assurances 
that where a State has relied on a local or regional government, agency 
or instrumentality for the implementation of any plan provision, the 
State has responsibility for ensuring adequate implementation of the 
plan provision.
    The principal control measures in the Revised 1999 CO Plan are 
Arizona's VEI program, the wintertime CBG program, and Maricopa 
County's woodburning restrictions program. We approved these programs 
at 68 FR 2912 (January 12, 2003), 69 FR 10161 (March 4, 2004), 64 FR 
60678, and 67 FR 48718 (July 25, 2002) respectively. As part of our 
approval actions, we found that Arizona had adequate personnel, funding 
and authority to implement these programs and had adequately provided 
for the enforcement of these programs.
    We have previously found that Arizona law includes the necessary 
assurances that where a State has relied on a local or regional 
government agency or instrumentality for the implementation of any plan 
provision, the State has responsibility for ensuring adequate 
implementation of the plan 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 if acceptable 
data are available and if certain other requirements are met. See CAA 
Section 107(d)(3)(D). Section 107(d)(3)(E) of the CAA provides that the 
Administrator may promulgate a redesignation of a nonattainment area to 
attainment if the 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 that the improvement in air 
quality is due to permanent and enforceable reductions in emissions 
resulting from implementation of the applicable implementation plan and 
the applicable Federal air pollutant control regulations and other 
permanent and enforceable reductions;
    (iv) The Administrator has fully approved a maintenance plan for 
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 and part D of the CAA.
    Before we can approve the redesignation request, we must determine 
that all applicable SIP elements have been fully approved. Approval of 
the applicable SIP elements may occur simultaneously with the final 
approval of the redesignation request.

VI. The MAG CO Redesignation Request and Maintenance Plan's Compliance 
With the CAA's Requirements for CO Redesignation Requests and 
Maintenance Plans

    We are proposing to approve the MAG Carbon Monoxide Redesignation 
Request and Maintenance Plan for the Maricopa County Nonattainment 
Area, May 2003 (``MAG CO Redesignation Request and Maintenance Plan''). 
The MAG CO Redesignation Request and Maintenance Plan was developed by 
the Maricopa Association of Governments (MAG), the lead air quality 
planning agency in Maricopa County. The Arizona Department of 
Environmental Quality (ADEQ) submitted this plan as a revision to the 
Arizona SIP on June 16, 2003 and EPA received it on June 24, 2003. We 
refer to this plan in this document as the MAG CO redesignation request 
and maintenance plan, the MAG maintenance plan, or variations of these.
    As submitted, the MAG CO Redesignation Request and Maintenance Plan 
consists of the main plan document and one volume of technical 
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. 
It uses UAM and the CAL3QHC microscale model to model air quality in 
1994 as a base year and in 2006 as an interim year and 2015 as the 
maintenance year

[[Page 60336]]

and demonstrates maintenance of the CO standard through 2015.
    The MAG CO Redesignation Request and Maintenance Plan shows that 
the principal sources contributing to past CO exceedances are gasoline 
on-road motor vehicles, gasoline non-road engines, and woodburning. MAG 
CO Redesignation Request and Maintenance Plan, p. ES-5.
    In earlier actions, we have already approved revisions to Arizona's 
CBG program and to Arizona's 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 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/or 
implement CO control measures. We approved these commitments as part of 
the serious area PM-10 plan approval on July 25, 2002 at 67 FR 48718. 
See 40 CFR 52.120(c)(100).
    We have reviewed the MAG CO Redesignation Request and Maintenance 
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 of this notice describe how the requirements of 
section 107(d)(3)(E) are addressed by the MAG submittal.

A. General SIP Requirements

    Section 110(k) of the CAA addresses our actions on submissions of 
revisions to a SIP. The CAA requires States to observe certain 
procedural requirements in developing SIP revisions for submittal to 
us. Section 110(a)(2) of the CAA requires that each SIP revision be 
adopted after reasonable notice and public hearing. This must occur 
prior to the revision being submitted by 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 adopted the 
MAG CO Redesignation Request and Maintenance Plan on May 28, 2003. 
These SIP revisions were adopted and submitted by ADEQ to us on June 
16, 2003. We received the submittal on June 24, 2003.
    We have evaluated MAG's submittal and have determined that the 
State met the requirements for reasonable notice and public hearing 
under section 110(a)(2) of the CAA. The MAG CO Redesignation Request 
and Maintenance Plan was deemed complete by operation of law six months 
after the submittal date.

B. Attainment of the CO NAAQS

    Section 107(d)(3)(E)(i) of the CAA states that for an area to be 
redesignated to attainment, the Administrator must determine that the 
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 of CO in 
the ambient air shall be measured by a reference method based on 40 CFR 
part 50, Appendix C and designated in accordance with 40 CFR part 53. 
We consider an area to be in attainment if each of the CO ambient air 
quality monitors in the area does not have more than one exceedance of 
the CO standard over a one-year period. See 40 CFR part 50.8 and 40 CFR 
part 50, Appendix C. If any monitor in the area's CO monitoring network 
records more than one exceedance of the CO standard during a one-year 
calendar period, then the area is in violation of the CO NAAQS.
    In addition, our interpretation of the CAA and EPA national policy 
has been that an area seeking redesignation to attainment must show 
attainment of the CO NAAQS for at least a continuous two-year calendar 
period. In addition, the area must also continue to show attainment 
through the 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 a finding of attainment of 
the CO standard for the Maricopa County nonattainment area on September 
22, 2003 (see 68 FR 55008). In our finding, we noted that not only did 
Maricopa County have the required clean data for the two years 
preceding the attainment date, but also that the Maricopa County 
nonattainment area has been in attainment for the national standards 
for CO since 1997. Further information on CO monitoring is presented in 
Chapter 3, page 3-15 of the MAG CO Redesignation Request and 
Maintenance 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 of the CO 
NAAQS. We note too that MAG 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 of National 
Ambient Monitoring Stations (NAMS) and State and Local Air Monitoring 
Stations (SLAMS) monitors in accordance with 40 CFR Part 58 to verify 
the continued attainment of the CO standard.

C. Meeting Applicable Requirements of Section 110 and Part 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 of the CAA. We interpret section 107(d)(3)(E)(v) to mean 
that for a redesignation to be approved by us, the State must meet all 
requirements that applied to the subject area prior to or at the time 
of submission of a 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 plan was 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 by December 31, 1995. The 
new attainment date was December 31, 2000.
    On July 8, 1999, ADEQ submitted the 1999 CO Plan to 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 to be revised to reflect this legislative change. MAG conducted 
new air quality modeling and documented the impact of the 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 found the submittal complete on October 9, 2001. We have analyzed 
the SIP elements in the Revised 1999 CO Plan that we are proposing for 
approval as part our action today, and have determined that they comply 
with the relevant requirements of section 110(a)(2).
    On June 16, 2003, ADEQ submitted the MAG Carbon Monoxide 
Redesignation Request and

[[Page 60337]]

Maintenance Plan for the Maricopa County Nonattainment Area, May 2003. 
The submittal was deemed complete by operation of law 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 of part D. Under part D, an area's 
classification indicates the requirements to which it was subject. 
Subpart 1 of part D sets forth the basic nonattainment requirements 
applicable to all nonattainment areas. Subpart 3 of part D contains 
specific provisions for serious CO nonattainment areas.
    The relevant subpart 1 requirements are contained in sections 
172(c) and 176. Our General Preamble (see 57 FR 13529, 13533, April 16, 
1992) provides EPA's interpretation of the CAA requirements for serious 
CO nonattainment areas.
    The General Preamble provides that the applicable requirements of 
CAA 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]. It is also worth noting that we interpret the 
requirements of sections 172(c)(2) [reasonable further progress--RFP] 
and 172(c)(6) [other measures] as being irrelevant to a redesignation 
request because they only have meaning for an area that is 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.
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    \10\ See EPA's September 4, 1992 John Calcagni memorandum 
entitled ``Procedures for Processing Requests to Redesignate Areas 
to Attainment'', and the General Preamble, 57 FR at 13564, dated 
April 16, 1992.
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    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 of subpart 3 of part 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 all nonattainment 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 have determined that areas being redesignated 
from nonattainment to attainment do not need to comply with the 
requirement that an NSR program be approved prior to redesignation 
provided that the area demonstrates maintenance of the standard without 
part D nonattainment NSR in effect. The rationale for this decision is 
described in a memorandum from Mary Nichols dated October 12, 1994 
(``Part D New Source Review (part D NSR) Requirements for Areas 
Requesting Redesignation to Attainment''). We have determined that the 
maintenance demonstration for Maricopa County does not rely on 
nonattainment NSR. Therefore, the State need not have a fully-approved 
nonattainment NSR program prior to approval of the redesignation 
request.
    Prevention of Significant Deterioration (PSD) is the replacement 
for NSR, and part of the obligation under PSD is for a new source to 
review increment consumption and maintenance of the air quality 
standards. The PSD program requires stationary sources to undergo 
preconstruction review before facilities are constructed or modified, 
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 with the 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) of the CAA.
    Information concerning CO monitoring in the Maricopa County 
nonattainment area is included in the Monitoring Network Review (MNR) 
prepared by MCESD and submitted to EPA. In Chapter 3, page 3-15 of the 
MAG CO Redesignation Request and Maintenance Plan, MAG commits to the 
continued operation of the existing NAMS and SLAMS CO monitors run by 
ADEQ and MCESD, according to all applicable Federal regulations and 
guidelines, even after the Maricopa County area is redesignated to 
attainment for CO. Annual review of the 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 of 40 CFR Part 58.
    Section 176 of the 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 EPA-approved maintenance 
plan, we have decided that a transportation conformity SIP is not an 
applicable requirement for purposes of evaluating a redesignation 
request under section 107(d) of the CAA. This decision is reflected in 
EPA's 1996 approval of the Boston carbon monoxide redesignation (See 61 
FR 2918, January 30, 1996).
    The relevant subpart 3 provisions were created when the CAA was 
amended on November 15, 1990. The new CAA requirements for serious CO 
areas, such as Maricopa County, required that the SIP be revised to 
include a 1990 base year emissions inventory (CAA section 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 and maintenance (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 of an oxygenated fuels 
program (CAA section 211(m)). How the State met these requirements and 
our approvals are described earlier in this notice.
    Regarding section 187(a)(1) of the CAA (base year 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 of the MAG 1993 Carbon Monoxide Plan 
for the Maricopa County Area (``CO Plan''). On April 4, 1994, ADEQ 
submitted updated and improved inventories as part of MAG's 1993 Carbon 
Monoxide Plan for the Maricopa County Area Addendum (``Addendum'').\11\ 
These revised

[[Page 60338]]

inventories reflected adjustments to growth factors and the impact of 
measures in Arizona House Bill 2001. Both submittals became complete by 
operation of law under CAA section 110(k)(1)(B) on May 15, 1994 and 
October 8, 1994, respectively.
---------------------------------------------------------------------------

    \11\ On August 9, 1993, EPA had issued a SIP call under section 
110(k)(5) of the CAA that required Arizona to submit a plan to EPA 
that demonstrated attainment of the CO NAAQS in the Phoenix area by 
December 31, 1995. As an area with a design value less than 12.7 
ppm, the State would 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 of a comprehensive, 
accurate, current inventory of actual emissions for all CO 
nonattainment areas whether or not they have a separate requirement 
to submit an attainment demonstration.
---------------------------------------------------------------------------

    We proposed approval of the 1990 base year inventory on September 
18, 1996 (61 FR 49087), and did not receive any comments on our 
proposed action. We will finalize that proposed action in our final 
rulemaking on today's proposed rule.
    Regarding section 187(a)(5) of the CAA (periodic emissions 
inventories), see Section IV.B. ``Emission Inventory'' of this 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-Approved SIP Under Section 110(k) of the CAA

    Section 107(d)(3)(E)(ii) of the CAA states that for an area to be 
redesignated to attainment, it must be 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 of the 
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 of the SIP 
under section 110(k) of the CAA.

E. Improvement in Air Quality Due to Permanent and Enforceable Measures

    Section 107(d)(3)(E)(iii) of the CAA provides that for an area to 
be redesignated to attainment, the Administrator must determine that 
the improvement in air quality is due to permanent and enforceable 
reductions in emissions resulting from implementation of the applicable 
implementation plan, implementation of applicable Federal air pollutant 
control regulations, and other permanent and enforceable reductions.
    As part of our 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 VEI program, traffic 
synchronization, and intelligent transportation systems (ITS) measures. 
These programs are further described in Chapter Five of the Revised 
1999 CO Plan.
    As described in Chapter Two, pages 2-11 to 2-15 of the MAG CO 
Redesignation Request and Maintenance Plan, significant additional 
emissions reductions were realized from Maricopa County's basic 
inspection and maintenance program (applicable to vehicles 1966 and 
newer), and beginning in 2000, the enhanced I/M program (applicable to 
vehicles 1966 and newer, with an exemption for vehicles of the five 
most recent model years).
    Oxygenated fuels are gasolines that are blended with additives that 
increase the level of oxygen 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 by EPA on March 4, 2004 (see 69 FR 
10161), Arizona's CBG program requires all Maricopa County-area gas 
stations in Area A \12\ to sell fuels containing a 3.5 percent minimum 
oxygen content (by weight) during the wintertime season, which runs 
from November 2 to March 31 of each year.
---------------------------------------------------------------------------

    \12\ Area A includes the urbanized portion of Maricopa County, a 
small portion of southern Yavapai County, and the western portions 
of Pinal County.
---------------------------------------------------------------------------

    Maricopa County has also been implementing the requirements of its 
clean burning fireplace ordinances. The Arizona legislature passed SB 
1427 in 1998 which required cities, towns, and counties in Area A to 
adopt, implement, and enforce an ordinance that complies with MAG's 
clean burning fireplace standards by December 31, 1998. The ordinance 
allows only the use of permanently-installed gas or electric log 
inserts, fireplaces, woodstoves, or other appliances that are certified 
by EPA, tested and listed by a nationally recognized testing agency to 
meet federal performance standards, or determined by the Maricopa 
County Control Officer to meet federal performance standards.
    We have evaluated the various State and Federal control measures, 
the original 1990 base year emission inventory, and the 1993, and 1996 
periodic emissions inventories, and believe that the improvement in air 
quality in the Maricopa County nonattainment area has resulted from 
emissions reductions that are permanent and enforceable.

F. Fully-Approved Maintenance Plan Under Section 175A

    Section 107(d)(3)(E)(iv) of the 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 of the CAA.
    Section 175A of the CAA sets forth the elements of a maintenance 
plan for areas seeking redesignation from nonattainment to attainment. 
The maintenance plan must demonstrate continued attainment of the 
applicable NAAQS for at least ten years after the Administrator 
approves a redesignation to attainment. Eight years after the 
promulgation of the redesignation, the State must submit a revised 
maintenance plan that demonstrates continued attainment for the 
subsequent ten-year period following the initial ten-year maintenance 
period. To address the possibility of future NAAQS violations, the 
maintenance plan must contain contingency measures, with a schedule for 
adoption and implementation, that are adequate to assure prompt 
correction of a violation. In addition, we issued further maintenance 
plan interpretations in the ``General Preamble for the Implementation 
of Title I of the Clean Air Act Amendments of 1990'' (57 FR 13498, 
April 16, 1992), ``General Preamble for the Implementation of Title I 
of the Clean Air Act Amendments of 1990: Supplemental'' (57 FR 18070, 
April 28, 1992), and the EPA guidance memorandum entitled ``Procedures 
for Processing Requests to Redesignate Areas to Attainment'' from John 
Calcagni, Director, Air Quality Management Division, Office of Air 
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 of 
the maintenance plan for 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 of 
section 175A and is consistent with the documents referenced above. Our 
analysis of the pertinent maintenance plan requirements, with reference 
to MAG's CO Redesignation Request and Maintenance Plan, is provided 
below.

[[Page 60339]]

1. Emissions Inventories--Attainment Year and Projections
    EPA's interpretation of the 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 of the CO NAAQS either by showing 
that future CO emissions will be equal to or less than the attainment 
year emissions or by providing a modeling demonstration. However, under 
the CAA, many areas (such as Maricopa County) were required to submit a 
modeled attainment demonstration to show that reductions in emissions 
would be sufficient to attain the applicable NAAQS. For these areas, 
the maintenance demonstration is to be based on the same level of 
modeling (see the ``Calcagni memo''). For the Maricopa County area, 
this involved the use of EPA's Urban Airshed Model (UAM) in conjunction 
with intersection hotspot modeling using the CAL3QHC model.
    The MAG CO Redesignation Request and Maintenance Plan submitted by 
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 Plan received by EPA on April 2, 
2001, and included an interim-year projection for 2006 along with the 
final maintenance year of 2015. More detailed descriptions of the 1994 
base year inventory from the Revised 1999 CO Plan, the 2006 projected 
inventory, and the 2015 projected inventory are documented in the MAG 
redesignation request and maintenance plan on page 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 2 below.

  Table 2.--Summary of CO Emissions in Tons per Day for Maricopa County
                       [For a Friday in December]
------------------------------------------------------------------------
                                       1994         2006         2015
------------------------------------------------------------------------
Point 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 that based on the information in Table 2, minor increases 
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 of the MAG CO 
Redesignation Request and Maintenance Plan's most significant measures 
reduce on-road vehicle 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 it is acceptable. Further 
information on these projected inventories may also be found on page 3-
9 of the MAG CO Redesignation Request and Maintenance Plan and in 
Appendix A, Exhibit 2, Section III-1 of the TSD.
2. Demonstration of Maintenance
    The Calcagni memo states that where modeling was relied on to 
demonstrate maintenance, the plan is to contain a summary of the air 
quality concentrations expected to result from the application of the 
control strategies. Also, the plan is to 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 Regulatory Application of the Urban 
Airshed Model for Areawide Carbon Monoxide (EPA-450/4-92-011a and b, 
June 1992; hereafter ``Guideline''). Most of the 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 and Maintenance 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 of the DIFFBREAK parameter, which in UAM is similar to 
mixing height, the height above ground through which substantial mixing 
occurs. Adjustment of minimum mixing heights is not ideal, but may be 
unavoidable in the absence of specific measured data on mixing heights, 
and has been accepted in other CO plans. Since CO is chemically inert, 
it is not unreasonable to adjust the air volume available for CO 
dilution, and thereby adjust CO concentration. This assumes diagnostic 
testing for other model inputs has been done, as is the case here.
    MAG's emission input development process used EPA's MOBILE6 model 
to estimate on-road mobile source emission factors instead of MOBILE5, 
per EPA 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 other inputs. 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 of the older MOBILE5a. One effect mitigating the 
higher MAG CO maintenance plan emissions is that while the base case 
(1994) on-road emissions are higher, they decline faster than in the 
Revised 1999 CO Plan because of the enhanced effects of vehicle fleet 
turnover incorporated in MOBILE6. So higher initial emissions in

[[Page 60340]]

the MAG CO Redesignation Request and Maintenance Plan are still 
consistent with maintenance of the 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 peak-increasing 
effect of the increased emissions. Revised traffic counts show that 
more of the 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 3 a.m. The 
assumed spatial distribution of cold 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 and Maintenance Plan is more 
realistic because cold start emissions occur relatively close to the 
beginning of trips, when commuting cars are more likely to be on local 
roads than on freeways. Another effect of this different spatial 
allocation of emissions is that they are more dispersed. Because of 
this and because of changes in various other model inputs, CO emissions 
are more widely distributed in the MAG CO Redesignation Request and 
Maintenance Plan.
    Finally, as mentioned above, mixing height was increased to improve 
model performance. This provided a greater volume for dilution of CO 
emissions, and thus a lower ambient concentration.
    A third factor in reconciling higher emissions with a relatively 
unchanged peak concentration is that, the MAG CO Redesignation Request 
and Maintenance Plan base case had less error and less negative bias 
than the Revised 1999 CO Plan's, i.e., it underpredicted by a smaller 
amount. The highest CO at any monitor in the MAG CO Redesignation 
Request and Maintenance 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 
and Maintenance 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 as in 
the Revised 1999 CO Plan were used, 27th Ave./Grand/Thomas Rd. and 35th 
Ave./Grand/Indian School Road. For the attainment demonstration, the 
results of the CAL3QHC modeling were combined with that from UAM for 
the cell containing the intersection, per EPA guidance. CAL3QHC 
contributions to peak concentrations was generally lower than was 
modeled for the Revised 1999 CO Plan. As discussed below, the decrease 
is partly due to updated traffic data. A shift in 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 of cold 
start emissions from idling emissions at intersections, in accordance 
with EPA guidance. Most cold start emissions occur within a few minutes 
of trip starts, so they have little affect on intersection emissions. 
Despite generally higher UAM predictions in the 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
----------------------------------------------------------------------------------------------------------------
WISR\1\...........................         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 9.0 ppm. 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 of 9.0 ppm.
    For episode selection, modeling domain, wind fields, initial and 
boundary conditions, sensitivity testing was essentially identical 
between the two episodes (see the EPA TSD for the Revised 1999 CO 
Plan). The tests done showed that the model was responding reasonably. 
MAG's modeling also meets EPA's performance goals on peak level, peak 
timing, and absolute error. Model predictions in the MAG CO 
Redesignation Request and Maintenance Plan are closer to observations 
than in the Revised 1999 CO Plan modeling.
    Since the peak values and general 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 of maintenance. Overall, the modeling done by 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 of Continued Attainment
    Continued attainment of the 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 of the 
MAG CO Redesignation Request and Maintenance Plan. On page 3-15 of the 
MAG CO Redesignation Request and Maintenance Plan, MAG commits to 
continue the operation of the CO monitors in the Maricopa County area 
and to annually review this monitoring network and make changes as 
appropriate.
    Also, on page 3-15 of the MAG CO Redesignation Request and 
Maintenance Plan, MAG commits to track mobile sources CO emissions 
(which are the

[[Page 60341]]

largest component of the inventories) through the ongoing submittal of 
periodic emissions inventories every three years in accordance with 
section 187(a)(5) of the 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 if additional measures should be considered.
    Based on the information above, we are proposing approval of these 
commitments as satisfying the relevant requirements of the 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) of the CAA requires 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 such measures.
    As stated on page 3-15 of the MAG CO Redesignation Request and 
Maintenance Plan, implementation of the contingency measures for the 
Maricopa County area will be triggered by two verified readings 
exceeding 9.0 ppm at one monitor during a single CO season (i.e., 
October 1 through March 31st). Since a violation of the NAAQS for 8-
hour CO occurs when the second highest reading at the same monitor over 
two consecutive years is greater than or equal to 9.5 ppm, this trigger 
is 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 on the following schedule: (a) 
Verification of the monitoring data to be completed three months after 
activation of the trigger; (b) applicable measure to be 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 on the 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 of the Maricopa County CO 
maintenance plan.

VII. EPA's Evaluation of the Transportation Conformity Requirements in 
the MAG CO Redesignation Request and Maintenance Plan

    One of the primary tests for conformity is to show that 
transportation plans and transportation improvement programs will not 
cause motor vehicle emissions to increase above levels needed to make 
progress towards and to meet air quality standards. The motor vehicle 
emissions levels needed to make progress toward and to meet the air 
quality standards are set in the area's air quality plans as 
``emissions budgets for motor vehicles''. More details about conformity 
tests are described in section IV.A of this notice. EPA has been using 
a process and specific criteria for determining the adequacy of 
emissions budgets in control strategy SIPs since a 1999 court ruling. 
This process is now codified in a recent revision to the conformity 
rule (see 69 FR 40004, July 1, 2004).
    The MAG CO Redesignation Request and Maintenance 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 to the maintenance year (2015) mobile source 
emissions inventory for CO for the attainment/maintenance area. The MAG 
CO Redesignation Request and Maintenance Plan and supporting 
documentation indicate that the 662.9 budget for 2015 is consistent 
with maintenance of the CO NAAQS throughout the maintenance period. 
Therefore, we are proposing to approve the 699.7 tons per day CO 
emissions budget for 2006 and the 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 a letter to ADEQ and MAG 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 in the Maricopa County nonattainment area on October 14, 
2003. However, we are not bound by that determination in acting on the 
maintenance plan.

VIII. GRIC Boundary Change Under CAA Section 107

    EPA is proposing to change the boundary of the Maricopa County CO 
nonattainment/maintenance area to exclude the Gila River Indian 
Reservation (``Reservation'').

A. Background

1. Current Area Boundary, Designation, and Classification
    Areas of the 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 for the 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 due to a failure to attain the 8-hour CO 
standard by December 31, 1995. 61 FR 39345 (July 29, 1996)
    Area boundaries and area classifications have been amended over the 
years under the applicable CAA provisions, either by request of a 
state, by operation of law, or by EPA initiative. For the State of 
Arizona, the current area designations and classifications are codified 
at 40 CFR 81.303.
2. GRIC's Request for a Boundary Change
    On July 14, 2004, the Gila River Indian Community (``Community''), 
a federally-recognized tribal government,\15\ submitted a formal 
request to EPA to revise the boundary of the Maricopa County CO 
nonattainment area to exclude the Reservation.\16\ The Community's 
analysis of air quality data existing at the time of and subsequent to 
the designation in 1978 as well as the nature of the CO sources on the 
Reservation demonstrated that the Reservation has not had a monitored 
or

[[Page 60342]]

predicted violation of the CO NAAQS since, and that no significant 
sources of CO exist on the Reservation.
---------------------------------------------------------------------------

    \15\ 67 FR 46329 (July 12, 2002).
    \16\ The Maricopa County CO nonattainment area includes the 
portion of the Reservation that lies within Maricopa County, 
approximately the northern 25% of the Reservation.
---------------------------------------------------------------------------

B. EPA Review of the 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 a nonattainment area on the basis of air quality data, 
planning and control considerations, or any other air quality-related 
considerations the Administrator deems appropriate.
2. The Gila River Indian Reservation Airshed
    The Gila River Indian Reservation consists of approximately 374,000 
acres in south central Arizona, south of the Phoenix metropolitan area. 
Currently, the Maricopa County (Phoenix area) CO nonattainment area 
includes the northern 92,000 acres of the Reservation. The Reservation 
is physically separated from the Phoenix metropolitan area by the 
Sierra Estrella and South Mountain Ranges. The Sierra Estrella Mountain 
Range runs north and south along the western edge of the Reservation. 
The South Mountain 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 of the 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 of the 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 of the 
urban area which are not part of the nonattainment area) has a 
population of 2,122,101, with a population density of over 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 
can be directly correlated to population density and land use patterns. 
The Community population density of 20 people per square mile is minor 
compared to all of Maricopa County, which has a density of over 230 
people per square mile. Commuting patterns on the 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, and the Reservation remains 
largely rural and agricultural. The Community plans to expand its 
agricultural base by investing millions of dollars in agricultural 
infrastructure.
    Total annual emissions of CO on the Reservation are less 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 of high traffic congestion, which do not exist 
on the Reservation. Therefore, there is substantial basis for 
concluding that the Reservation is an insignificant generator of CO 
emissions.
4. CO Planning Issues
    Attainment of the 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 air 
pollution control authorities are not administering EPA-approved air 
regulatory programs over the Reservation; consequently, the SIP rules 
that were applied to the metropolitan area and resulted in attainment 
of the NAAQS did not apply to the Reservation. Furthermore, due to the 
Reservation's lack of CO sources, it was never considered necessary to 
apply CO limits to sources in the Reservation.\17\
---------------------------------------------------------------------------

    \17\ EPA could have applied CO limits to sources on the 
Reservation, as it has authority under CAA 301(d) to promulgate 
regulations for Indian country as necessary or appropriate ``to 
achieve the appropriate purpose'' of the Act.
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    Just as it was clear that it was not necessary for an attainment 
plan to be applicable to the Reservation for the Phoenix area to attain 
the CO NAAQS, it is clear to EPA that it will not be necessary for a 
maintenance plan to be applicable to the Reservation for the Phoenix 
area to maintain attainment of the NAAQS.

C. Redesignation of the Northern Portion of the Reservation

    In view of the above considerations, and because no CO air quality 
data exists for the Reservation, EPA believes ``nonclassifiable/
attainment'' is the appropriate designation for the entire Reservation, 
including that portion heretofore included in the nonattainment area. 
Therefore, EPA proposes to redesignate to ``nonclassifiable/
attainment'' the portion of the Reservation that is now within the 
nonattainment area, and make it part of the surrounding 
nonclassifiable/attainment area.

IX. Proposed Action

    We are soliciting public comment on all aspects of this proposed 
SIP rulemaking action. We will consider your comments in deciding our 
final action if your comments are received by November 8, 2004.
    We propose to approve the following elements of the 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 that the 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 of reasonable 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 of vehicle 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 plan for the years 2000, 2006 and 2015 under the 
transportation conformity rule, 40 CFR Part 93, subpart A;
    11. Demonstration of maintenance under section 175A(a) and a fully-
approved maintenance plan under section 175A;
    12. Maintenance plan contingency measures under section 175A(d);
    13. Commitment for subsequent maintenance plan revisions under 
section 175A(b);

[[Page 60343]]

    14. Redesignation of that portion of the Gila River Indian 
Reservation that is now within the nonattainment area to 
``nonclassifiable/attainment'; and
    15. A determination that the improvement in air quality in the 
Maricopa County nonattainment area is due to permanent and enforceable 
reductions in emissions resulting from the implementation of the 
applicable implementation plan, implementation of applicable Federal 
air pollution 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 (required 
by 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 of MAG'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 of the portion of 
the Gila River Indian Community which is in the Maricopa County CO 
nonattainment area to ``unclassifiable/attainment'' for CO.

X. Statutory and 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 by the Office of Management and 
Budget. For this reason, this action is also not subject to Executive 
Order 13211, ``Actions Concerning Regulations That Significantly Affect 
Energy Supply, Distribution, or Use'' (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 
imposed by 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 duty beyond that required by state law, it does 
not contain any unfunded mandate or significantly or uniquely affect 
small governments, as described in the Unfunded Mandates Reform Act of 
1995 (Public Law 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 input by tribal officials in the development of regulatory 
policies that have tribal implications.'' ``Policies that have tribal 
implications'' is defined in the Executive Order to include 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 of power and responsibilities between the 
Federal government and Indian tribes.''
    Under section 5(b) of Executive Order 13175, EPA may not issue a 
regulation that has tribal implications, that imposes substantial 
direct compliance costs, and that is not required by statute, unless 
the Federal government provides the funds necessary to pay the direct 
compliance costs incurred by tribal governments, or EPA consults with 
tribal officials early in the process of developing the proposed 
regulation. Under section 5(c) of Executive Order 13175, EPA may not 
issue a regulation that has tribal implications and that preempts 
tribal law, unless the Agency consults with tribal officials early in 
the process of developing 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, it will neither impose 
substantial direct compliance costs on tribal governments, nor preempt 
State law. Thus, the requirements of sections 5(b) and 5(c) of the 
Executive Order do not apply to this rule.
    Consistent with EPA policy, EPA nonetheless consulted with 
representatives of tribal governments early in the process of 
developing this regulation to permit them to have meaningful and timely 
input into its development. Representatives of tribal governments 
approached EPA two years ago and requested that EPA make this boundary 
change. We agree with the technical and policy rationale the tribe 
provided, and believe that all tribal concerns have been met.
    In the spirit of Executive Order 13175, and consistent with EPA 
policy to promote communications between EPA and tribal governments, 
EPA specifically solicits additional comment on this proposed rule from 
tribal officials.
    This action also does not have Federalism implications because it 
does not have substantial direct effects on the States, on the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government, 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 of power and responsibilities established in the Clean 
Air Act. This proposed rule also is not subject to Executive Order 
13045 ``Protection of Children from Environmental Health Risks and 
Safety Risks'' (62 FR 19885, April 23, 1997), because it is 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 of a prior existing requirement for the 
State to use voluntary consensus standards (VCS), EPA has no authority 
to disapprove a SIP submission for failure to use VCS. It would thus be 
inconsistent with applicable law for EPA, when it reviews a SIP 
submission, to use VCS in place of a SIP submission that otherwise 
satisfies the provisions of the Clean Air Act. Thus, the requirements 
of section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (15 U.S.C. 272 note) do not apply. This proposed rule does 
not impose an information collection burden under the provisions of the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).

List of Subjects

40 CFR Part 52

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

40 CFR Part 81

    Air pollution control, National parks, Wilderness areas.

    Dated: September 21, 2004.
Laura Yoshii,
Acting Regional Administrator, Region 9.
[FR Doc. 04-22485 Filed 10-7-04; 8:45 am]
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