Document ID: EPA-R09-OAR-2010-0491-0001
Agency: epa
Document Type: Proposed Rule
Title: Designation of Areas for Air Quality Planning Purposes: Pinal County, AZ, PM10
Posted Date: 2010-10-01T04:00Z

[Federal Register: October 1, 2010 (Volume 75, Number 190)]
[Proposed Rules]               
[Page 60680-60689]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr01oc10-27]                         

[[Page 60680]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 81

[EPA-R09-OAR-2010-0491; FRL-9209-4]

 
Designation of Areas for Air Quality Planning Purposes; State of 
Arizona; Pinal County; PM10

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to section 107(d)(3) of the Clean Air Act, EPA is 
proposing to redesignate from ``unclassifiable'' to ``nonattainment'' 
an area generally covering the western half of Pinal County, Arizona, 
for the 1987 national ambient air quality standard for particles with 
an aerodynamic diameter less than or equal to a nominal 10 micrometers 
(PM10), and therefore also proposing to revise the 
boundaries of the existing ``rest of state'' unclassifiable area. EPA's 
proposal to establish this new PM10 nonattainment area, 
referred to as ``West Pinal,'' is based on numerous recorded violations 
of the PM10 standard at various monitoring sites within the 
county. EPA's proposed boundaries would encompass all land 
geographically located within Pinal County west of the north-south line 
defined by the boundary between Townships 10E and 11E, but excluding 
the main reservation of the Tohono O'odham Nation (TON) and excluding 
the Apache Junction portion of the existing Phoenix PM10 
nonattainment area. San Carlos Apache lands, which are located in the 
eastern quarter of the county, would be excluded from the proposed 
nonattainment area along with the rest of the eastern half of the 
county. If finalized as proposed, the new ``West Pinal'' 
PM10 nonattainment area would be classified as ``moderate'' 
by operation of law. The effect of this action would be to establish 
and delineate a new PM10 nonattainment area within Pinal 
County and thereby to impose certain planning requirements on the State 
of Arizona to reduce PM10 concentrations within this area, 
including, but not limited to, the requirement to submit, within 18 
months of redesignation, a revision to the Arizona state implementation 
plan that provides for attainment of the PM10 standard as 
expeditiously as practicable but no later than the end of the sixth 
calendar year after redesignation. Lastly, EPA is deferring action on 
the status of certain tribal lands located within this area, including 
the tribal lands of the Ak-Chin Indian Community and the Gila River 
Indian Community, as well as TON's Florence Village and San Lucy Farm, 
pending further consultation with the affected tribes.

DATES: Any comments must arrive by November 1, 2010.

ADDRESSES: Submit comments, identified by docket number EPA-R09-OAR-
2010-0491, by one of the following methods:
    1. Federal eRulemaking Portal: http://www.regulations.gov. Follow 
the on-line instructions.
    2. E-mail: vagenas.ginger@epa.gov.
    3. Mail or deliver: Ginger Vagenas (Air-2), U.S. Environmental 
Protection Agency Region IX, 75 Hawthorne Street, San Francisco, CA 
94105-3901.
    Instructions: All comments will be included in the public docket 
without change and may be made available online at http://
www.regulations.gov, including any personal information provided, 
unless the comment includes Confidential Business Information (CBI) or 
other information whose disclosure is restricted by statute. 
Information that you consider CBI or otherwise protected should be 
clearly identified as such and should not be submitted through http://
www.regulations.gov or e-mail. http://www.regulations.gov is an 
``anonymous access'' system, and EPA will not know your identity or 
contact information unless you provide it in the body of your comment. 
If you send e-mail directly to EPA, your e-mail address will be 
automatically captured and included as part of the public comment. If 
EPA cannot read your comment due to technical difficulties and cannot 
contact you for clarification, EPA may not be able to consider your 
comment.
    Docket: The index to the docket for this action is available 
electronically at http://www.regulations.gov and in hard copy at EPA 
Region IX, 75 Hawthorne Street, San Francisco, California. While all 
documents in the docket are listed in the index, some information may 
be publicly available only at the hard copy location (e.g., copyrighted 
material), and some may not be publicly available in either location 
(e.g., CBI). To inspect the hard copy materials, please schedule an 
appointment during normal business hours with the contact listed in the 
FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: Ginger Vagenas, EPA Region IX, (415) 
972-3964, vagenas.ginger@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us'' and 
``our'' refer to EPA.

Table of Contents

I. Background
II. EPA's Decision to Address PM10 Violations Monitored 
in Pinal County Through Redesignation
III. State of Arizona's Recommendation for Boundaries for New 
Nonattainment Area
IV. EPA's Review of the State's Recommendation and Rationale for 
Proposed Boundaries
V. EPA's Review of Recommendations From Affected Indian Tribes
VI. Proposed Action and Request for Public Comment
VII. Statutory and Executive Order Reviews

I. Background

    On July 1, 1987, EPA revised the national ambient air quality 
standards (NAAQS or ``standards'') for particulate matter (52 FR 
24634), replacing total suspended particulates as the indicator for 
particulate matter with a new indicator called PM10 that 
includes only those particles with an aerodynamic diameter less than or 
equal to a nominal 10 micrometers.\1\ In order to attain the NAAQS for 
24-hour PM10, an air quality monitor cannot measure levels 
of PM10 greater than 150 micrograms per cubic meter 
([micro]g/m\3\) more than once per year on average over a consecutive 
three-year period. The rate of expected exceedances, therefore, 
indicates whether a monitor attains the air quality standard.
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    \1\ The 1987 PM10 standard included a 24-hour (150 
micrograms per cubic meter ([micro]g/m\3\)) and an annual standard 
(50 [micro]g/m\3\). In 2006, EPA revoked the annual standard. See 71 
FR 61144 (October 17, 2006) and 40 CFR 50.6.
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    Most of Pinal County, Arizona, including the area that is the 
subject of today's action, was included in the ``rest of state'' area, 
which was designated ``unclassifiable'' for PM10 by 
operation of law upon enactment of the 1990 amendments to the Clean Air 
Act (CAA or ``Act'').\2\ See section 107(d)(4)(B)(iii). The 
PM10 designations established by operation of law under the 
CAA, as amended in 1990, are known as ``initial'' designations. The CAA 
grants EPA the authority to change the designation of, or 
``redesignate,'' such areas in light of changes in circumstances. More 
specifically, CAA section 107(d)(3) authorizes EPA to revise the 
designation of areas (or portions thereof) on the

[[Page 60681]]

basis of air quality data, planning and control considerations, or any 
other air-quality-related considerations that EPA deems appropriate. 
Pursuant to CAA section 107(d)(3), EPA in the past has redesignated 
certain areas in Arizona to nonattainment for the PM10 
NAAQS, including the Payson and Bullhead City areas. See 56 FR 16274 
(April 22, 1991); and 58 FR 67334 (December 21, 1993).
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    \2\ While most of Pinal County was designated 
``unclassifiable,'' two PM10 planning areas that extend 
into Pinal County were designated under the CAA, as amended in 1990, 
as ``nonattainment:'' The Phoenix planning area, which includes the 
Apache Junction area within Pinal County; and the Hayden/Miami 
planning area, which includes the northeastern portion of the 
county. See 56 FR 11101 (March 15, 1991); 56 FR 56694 (November 6, 
1991); and 57 FR 56762 (November 30, 1992). In 2007, we approved a 
redesignation request by the State of Arizona to split the Hayden/
Miami PM10 nonattainment area into two separate 
PM10 nonattainment areas. See 72 FR 14422 (March 28, 
2007). Today's proposed action would not affect these pre-existing 
PM10 nonattainment areas. EPA codifies area designations 
in 40 CFR part 81. The area designations for the State of Arizona 
are codified at 40 CFR 81.303.
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II. EPA's Decision to Address PM10 Violations Monitored in 
Pinal County Through Redesignation

    As noted above, EPA has the authority under CAA section 107(d)(3) 
to redesignate areas (or portions thereof) on the basis of air quality 
data, planning and control considerations, or any other air-quality-
related considerations. Last year, under CAA section 107(d)(3)(A), EPA 
notified the Governor of Arizona and tribal leaders of the four Indian 
Tribes (whose Indian country is located entirely, or in part, within 
Pinal County) that the designation for Pinal County, and any nearby 
areas that may be contributing to the monitored violations in Pinal 
County, should be revised. Our decision to initiate the redesignation 
process stemmed from review of 2006-2008 ambient PM10 
monitoring data from PM10 monitoring stations within the 
county that showed widespread, frequent, and in some instances, severe, 
violations of the PM10 standard.\3\
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    \3\ In a letter dated October 14, 2009, EPA notified the State 
of Arizona that the PM10 designation in Pinal County 
should be revised. EPA notified the tribal leaders of the Ak-Chin 
Indian Community, Gila River Indian Community, San Carlos Apache 
Tribe, and Tohono O'odham Nation by letters dated December 30, 2009.
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    Table 1, below, presents a summary of the latest available quality-
assured PM10 monitoring data (2007-2009). A map showing the 
location of the monitors is included in our Technical Support Document 
(TSD), contained in the docket for this rulemaking.

   Table 1--Pinal County--PM10 Air Quality Monitoring Data, 2007-2009
------------------------------------------------------------------------
                                                          PM10 Expected
              Site name                    AQS* ID        exceedances**
                                                            2007-2009
------------------------------------------------------------------------
Apache Junction***..................     04-021-3002-1                 0
Casa Grande.........................     04-021-0001-1                 0
                                         04-021-0001-3               4.7
Combs School (Queen Creek)..........     04-021-3009-3              17.6
Coolidge............................     04-021-3004-1                 2
Cowtown (southeast of Maricopa).....     04-021-3013-1             112.9
                                         04-021-3013-3             139.8
Eloy................................     04-021-3014-1                 0
Mammoth.............................     04-021-3006-1                 0
Marana (Pinal Air Park).............     04-021-3007-1                 0
Maricopa............................     04-021-3010-3              12.6
Pinal County Housing/PCH (approx. 11     04-021-3011-1               6.5
 miles east of Casa Grande).........
                                         04-021-3011-2               5.9
                                         04-021-3011-3              15.6
Riverside (Kearny)..................     04-021-3012-1                 0
Stanfield (approx. 15 miles west of      04-021-3008-1              16.4
 Casa Grande).......................
                                         04-021-3008-3              17.8
Bapchule (Gila River Indian              04-021-7004-1               6.6
 Community monitors)................
                                         04-021-7004-2               7.9
------------------------------------------------------------------------
*AQS (Air Quality System) is an EPA database of ambient air quality.
**The 24-hour PM10 standard is met when the 3-year average of the
  expected exceedances is equal to or less than one.
***The Apache Junction site is located in the existing Phoenix PM10
  nonattainment area.

    As shown in Table 1, the data from 2007-2009 reveal violations at 
the PM10 monitors located in Queen Creek, Casa Grande, 
Coolidge, Cowtown (which is southeast of Maricopa), Maricopa, 
Stanfield, at the Pinal County Housing Complex (which is east of Casa 
Grande, roughly half-way between Coolidge and Eloy), and within the 
Gila River Indian Reservation. Expected annual exceedances (of the 150 
[micro]g/m\3\ 24-hour standard) at these monitoring sites range from 
two (at Coolidge) to more than 100 (at Cowtown). (For the purposes of 
comparison, the NAAQS is met when the 3-year average of the expected 
exceedances is equal to or less than one.) Maximum 24-hour 
concentrations measured at a number of these sites (such as Cowtown, 
Maricopa and Stanfield) can be more than two to three times the level 
of the standard. In light of the widespread, frequent, and severe 
violations of the PM10 standard monitored at various 
monitoring sites in Pinal County, EPA continues to believe that the SIP 
planning and control requirements that are triggered by redesignation 
of an area to nonattainment for the PM10 NAAQS would be the 
most appropriate means to ensure that this air quality problem is 
remedied.
    Section III of this document describes the State of Arizona's 
recommendation with respect to the boundaries of this new 
PM10 nonattainment area, and section IV of this document 
summarizes EPA's review of the State's recommendation and rationale for 
EPA's proposed boundaries. Section V describes the Indian Tribes' 
recommendations and our corresponding responses. Section VI describes 
our proposed action and the corresponding CAA planning requirements 
that would thereby be triggered.

III. State of Arizona's Recommendation for Boundaries for New 
Nonattainment Area

    Pursuant to section 107(d)(3)(B) of the Act, the Governor of 
Arizona responded to EPA's October 14, 2009 notification that the 
PM10 designation of Pinal County, and any nearby areas that 
may be contributing to violations in Pinal County, should be revised. 
The Governor responded in a letter dated

[[Page 60682]]

March 23, 2010 in which the Governor recommended a partial-county 
nonattainment area.\4\
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    \4\ Letter from Jan Brewer, Governor of Arizona, to Jared 
Blumenfeld, Regional Administrator, EPA Region IX, dated March 23, 
2010.
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    The boundaries of the prospective PM10 nonattainment 
area recommended by the Governor of Arizona encompass a portion of 
central and western Pinal County, and form an area that resembles a 
backwards ``L.'' \5\ See figure 2 of EPA's TSD for a map of both the 
State's recommended boundaries as well as EPA's proposed boundaries. 
The state-recommended area includes all or most of the cities of 
Maricopa, Coolidge, Casa Grande and the Pinal County portion of the 
town of Queen Creek, as well as the western-most portion of the town of 
Florence and the northern-most portion of the city of Eloy. It includes 
an area that at its western-most boundary includes nearly all of the 
City of Maricopa. The southern boundary is defined by a line that 
coincides approximately with Interstate 8. The area continues to the 
east for approximately 35 miles where it extends to the north, 
including portions of Florence and Coolidge, and the Pinal County 
portion of Queen Creek, and terminates just south of Apache Junction. 
The eastern boundary is defined by the north-south line between 
Townships 8E and 9E. The northern boundary follows the county line 
south from the Apache Junction area and then follows the boundary of 
the Gila River Indian Reservation to close back around to the 
recommended western boundary. See the Governor's March 23, 2010 letter 
for the legal description of the State's recommended boundaries by 
township and range and for an enclosed map illustrating this area.
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    \5\ The Governor explicitly excludes Indian country, which is 
appropriate given that the State of Arizona is not authorized to 
administer programs under the CAA in the affected Indian country. 
The ``backwards L'' shape of the recommended area is partly 
explained by this exclusion because the recommended area partially 
surrounds Indian country.
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    In support of the Governor's recommendation, on March 26, 2010, the 
Arizona Department of Environmental Quality (ADEQ) submitted to EPA a 
technical report entitled, ``Arizona Air Quality Designations, 
Technical Support Document, Boundary Recommendation for the Pinal 
County 24-hour PM10 Nonattainment Area (March 15, 2010),'' 
(herein referred to as ADEQ's ``technical report''). ADEQ's technical 
report compiles and evaluates information addressing nine factors \6\ 
derived from and discussed in EPA guidance on designation criteria; see 
citation on page 2 of ADEQ's technical report to Memorandum from Robert 
J. Meyers, EPA Acting Assistant Administrator, ``Area Designations for 
the Revised 24-Hour Fine Particle National Ambient Air Quality 
Standard,'' dated June 8, 2007.
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    \6\ The nine factors considered in ADEQ's technical report are 
air quality data, emissions data, population density and degree of 
urbanization, traffic and commuting patterns, growth rates and 
patterns, meteorology, geography/topography, jurisdictional 
boundaries, and level of control of emission sources.
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    ADEQ points to a number of elements that it believes support the 
recommended boundaries. Specifically, ADEQ claims that its recommended 
area would include: all of the violating monitors; the majority of 
PM10 emissions generated within the county; the vast 
majority of the county's population; the rapidly growing urbanized and 
developed areas, high-traffic Interstate corridors and areas with the 
highest employment densities; the significant growth areas along 
Interstates 8 and 10; and the agricultural basin where stagnation 
conditions are known to impact PM10 concentrations. ADEQ 
also believes that its recommended redesignation would maintain 
jurisdictional cohesiveness. To buttress its recommended exclusion of 
eastern Pinal County from the new nonattainment area, ADEQ compares 
these factors as they apply to western Pinal County with those for 
eastern Pinal County. ADEQ asserts that in contrast to the western 
portion of Pinal County, the eastern portion has no violating monitors, 
contains few emissions sources (other than certain major sources that 
are already included in an existing PM10 nonattainment 
area), is largely undeveloped and has limited growth potential. As set 
forth below in more detail, while EPA believes this characterization 
applies to the eastern half of Pinal County, EPA also believes that the 
western portion that should be redesignated is far more extensive than 
the State's recommendation.

IV. EPA's Review of the State's Recommendation and Rationale for 
Proposed Boundaries

    CAA section 107(d)(1)(A) generally defines a nonattainment area as 
any area that does not meet, or that contributes to ambient air quality 
in a nearby area that does not meet, the national primary or secondary 
ambient air quality standard for the relevant pollutant. Thus, in 
reviewing the State's recommended boundaries, EPA has considered not 
only areas where violations of the relevant NAAQS have been monitored, 
but also that contribute to such violations.
    EPA guidance \7\ provides for the use of ``a qualitative analysis 
of the area of representativeness of the monitoring station, together 
with the consideration of terrain, meteorology, and sources of 
emissions * * *'' in defining nonattainment area boundaries for 
PM10. Consistent with that guidance, EPA generally 
recommends that States identify nonattainment area boundaries based on 
the weight of evidence of the following factors and other relevant 
information:
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    \7\ PM10 SIP Development Guideline, EPA-450/2-86-001, 
June 1987.

--Air quality data;
--Pollutant emissions;
--Population density and degree of urbanization;
--Traffic and commuting patterns;
--Growth;
--Meteorology;
--Geography and topography;
--Jurisdictional boundaries; and
--Level of control of emissions sources.
See, e.g., Memorandum from Robert J. Meyers, EPA Acting Assistant 
Administrator, ``Area Designations for the Revised 24-Hour Fine 
Particle National Ambient Air Quality Standard,'' dated June 8, 2007. 
EPA also looks to the same kinds of factors in the context of 
redesignations. See, e.g., EPA's proposed (73 FR 22307, at 22308-22310, 
April 25, 2008) and final approval (73 FR 66759, November 12, 2008) of 
a state request to redesignate the San Joaquin Valley PM10 
nonattainment area. In addition, CAA section 107(d)(3)(A) allows EPA, 
in redesignating areas to nonattainment, to take into consideration 
``any other air-quality-related considerations.'' In its technical 
report, ADEQ refers to the nine factors in developing the State's 
recommended boundaries for the new PM10 nonattainment area. 
In the following paragraphs, we review and evaluate ADEQ's nine factor 
analysis.
    Air Quality Data. ADEQ's technical report summarizes 2006-2008 
PM10 monitoring data from 12 monitoring sites within Pinal 
County. Most of the monitoring sites are located in the west central 
portion of the county (Maricopa, Cowtown, Stanfield, Casa Grande, Pinal 
County Housing Complex, and Coolidge). Two are located in the southern 
portion (Eloy and Pinal Air Park); two are located in the northern 
portion [Apache Junction and Combs School (located in Queen Creek)]; 
and two are located in the far eastern portion of the county (Riverside 
and Mammoth). The Apache Junction and Riverside

[[Page 60683]]

monitoring sites are located within existing PM10 
nonattainment areas.
    Based on 2006-2008 data, ADEQ finds six of the monitoring sites to 
be in violation of the PM10 NAAQS. EPA has updated this 
monitoring information by reviewing 2007-2009 data. Although we find 
that these data are largely consistent with the data presented by ADEQ, 
the more recent data set shows seven violating monitors (not counting 
the PM10 monitoring site on the Gila River Indian 
Reservation) rather than six. Coolidge is the additional monitoring 
site that is newly violating based on the more recent data set. In its 
technical report, ADEQ notes that its proposed boundaries include the 
locations of all of the violating monitors within Pinal County. While 
we agree that Arizona's proposed boundaries do in fact include all of 
the violating monitors (i.e., other than the monitoring site located 
within the Gila River Indian Reservation and those located within 
existing PM10 nonattainment areas), we disagree with ADEQ's 
contention that its proposed boundaries include all areas that do not 
experience violations but nonetheless contribute to the violations that 
are recorded at the monitoring sites based on an evaluation of the 
other eight factors as discussed in the following paragraphs.
    Emissions Data. ADEQ developed an annual emissions inventory of 
PM10 sources in the county for the year 2007 for the purpose 
of defining a boundary for the new nonattainment area. ADEQ's inventory 
relies on a number of different data sources, assumptions, and methods 
(including EPA's MOBILE model and compilation of emissions factors (AP-
42)) to calculate annual PM10 emissions in the county. 
ADEQ's inventory points to fugitive emissions from vehicular traffic on 
paved and unpaved roads as the single largest source category, followed 
in importance by agricultural sources (including concentrated animal 
feeding operations), industrial sources, and construction. ADEQ's 
technical report includes maps that show the relative distribution of 
emissions generated within the county using 4-kilometer grid cells. See 
in particular the following maps in the State's technical report: 
Figure 3-3 on page 8 (all PM10 sources) and figure 3-4 on 
page 11 (paved and unpaved on-road sources). The maps show that 
PM10 emissions in the county are concentrated in the western 
half of the county, with the highest emissions densities in the west 
central portion of the county. In contrast, the eastern half of the 
county (outside of the existing nonattainment areas) is characterized 
predominantly by the lowest category of emissions densities (i.e., 0 to 
20 tons per year per 4-kilometer grid). See page 8 of ADEQ's technical 
report.
    While EPA finds that the PM10 emissions inventory for 
Pinal County and ADEQ's corresponding maps are helpful in defining the 
boundaries of the new nonattainment area, we do not believe that they 
justify ADEQ's conclusions about its recommended boundaries. ADEQ 
claims that the emissions inventory and maps demonstrate that sources 
in the eastern and southern regions of the county do not 
``significantly contribute'' to violations in the other regions of the 
county. See page ES-3 of ADEQ's technical report. EPA notes, however, 
that CAA section 107(d)(1)(A) defines a nonattainment area as one that 
does not meet, or that ``contributes to'' ambient air quality in a 
nearby area that does not meet the NAAQS. The definition of 
nonattainment areas is not limited to areas that, in ADEQ's words, 
``significantly'' contribute to a violating area. Moreover, ADEQ's maps 
show that areas immediately to the east and south of the recommended 
area (but still within the western half of the county) include the same 
types of emissions sources, with similar emissions densities, as those 
that predominate within the recommended area. For example, figure 3-3 
(page 8 of State's technical report) shows emissions densities similar 
to those estimated within the State's recommended boundaries to the 
east in Coolidge and Florence, as well as south to Eloy. In addition, 
figures 3-4, 3-7, and 3-10 (on pages 11, 14, and 17, respectively, of 
the State's technical report) illustrate the locations of unpaved roads 
(with average daily traffic volumes greater than 100) and show that 
higher relative concentrations of PM10 emissions from such 
sources as vehicle entrainment of dust over paved and unpaved roads, 
tilling and harvesting, and concentrated animal feeding operations 
(CAFOs) extend to central, and south central Pinal County. Thus, the 
emissions inventory data and related maps do not support the State's 
recommended boundaries but rather argue for a larger nonattainment area 
consisting of the western half of the county.
    In contrast, EPA's proposed boundaries include all of the areas for 
which emissions data show relatively higher PM10 emissions 
from the types of sources contributing the most to the overall 
PM10 emissions inventory. For instance, based on the 
information sources described above in the State's technical report, 
EPA's proposed boundaries include the areas of relatively higher 
emissions densities in and around Coolidge, Florence, and Eloy that 
reflect the same types of PM10-generating activities 
(vehicle entrainment of dust over paved and unpaved roads, tilling and 
harvesting, and CAFOs) as found within the smaller nonattainment area 
boundaries recommended by the State.
    Population density, degree of urbanization, growth rate and 
patterns. This factor reflects EPA's belief that the size, density, and 
location of population can be indicative of emissions activity that 
contributes to violations of the PM10 NAAQS in an area. 
ADEQ's technical report presents population growth and density figures 
for municipalities in Pinal County. The data show that Pinal County has 
grown dramatically over the past decade (nearly doubling from a 
population of approximately 180,000 in 2000 to nearly 360,000 in 2008). 
EPA independently collected and reviewed population-related information 
and notes that the populations of the largest cities and towns in the 
western half of the county, such as (the city of) Maricopa (2008 
population of approximately 46,000), Casa Grande (41,000), Apache 
Junction (33,000), Florence (21,000), and Eloy (13,000), contrast 
sharply with much smaller populations in the largest cities and towns 
in the eastern half of the county, including Superior (3,000), Kearny 
(3,000), and Mammoth (3,000). See page 14 of EPA's TSD.
    ADEQ also submitted maps showing population densities both under 
current conditions and projections for the year 2030 when the 
population of Pinal County is anticipated to exceed 1,000,000. Under 
existing conditions, higher population densities are found in the west 
central portion of the county, but there are also population centers in 
the northern (Apache Junction and Queen Creek) and southern portions 
(Eloy) of the county. ADEQ's maps show that future growth is expected 
to be concentrated in the Interstate 8 and 10 corridors, which extend 
through the west central and southern portions of the county, although 
a certain amount of growth is also expected in the Falcon Valley area 
farther to the east.
    In its technical report, ADEQ concludes that the eastern and 
southern portions of the county are largely undeveloped and have very 
low population densities, and finds that this information provides 
support for the State's recommended boundaries. However, like the 
emissions data discussed above, we believe that the data do not justify 
the restricted nature of the State's recommended boundaries, which 
exclude much of the western half of the County. Specifically, EPA

[[Page 60684]]

believes that the State's recommended exclusion of areas in the eastern 
and southern sections of the western half of the county is contradicted 
by evidence showing that land use development in Pinal County extends 
further east and south than the State's recommended boundaries. For 
example, the State's recommended boundaries fail to include the 
agricultural and more urbanized uses in and around Eloy and the future 
growth areas along the two Interstate corridors. See figures 3-13 and 
3-14 from the State's technical report. In contrast, EPA's proposed 
boundaries would include all of the western half of Pinal County 
(excluding TON's main reservation and the Apache Junction portion of 
the Phoenix PM10 nonattainment area) and thereby would 
include the areas with relatively higher population densities and most 
of the areas where significant levels of growth are expected.
    Traffic and commuting patterns. This factor considers the commuting 
patterns of residents in, and commuters to, Pinal County. More 
specifically, this factor considers the number of commuters in each 
surrounding county who drive to Pinal County, the percent of total 
commuters in each county who commute to Pinal County, the percent of 
total commuters in each county who commute into the statistical area in 
which Pinal County is located, as well as the total vehicle miles 
traveled (VMT) for each county.
    ADEQ's technical report (page 23) presents statistics from the 2000 
census quantifying the number of commuters from each county within the 
State of Arizona to jobs within Pinal County, and the number of 
commuters residing in Pinal County to jobs in Maricopa and Pima 
counties. The data from 2000 indicate that approximately 10,000 
commuters, or roughly 20% of total commuters to jobs within Pinal 
County, reside outside of Pinal County. Conversely, approximately 
36,000 (roughly 80%) of commuters travel solely within Pinal County. 
Almost 80% of the out-of-county commuters reside to the north in 
Maricopa County, and nearly all remaining out-of-county commuters 
commuting to Pinal County reside to the south in Pima County. Moreover, 
nearly 40% of commuters residing in Pinal County work in either 
Maricopa or Pima counties, whereas 60% of commuters residing in Pinal 
County also work in Pinal County.
    EPA independently reviewed these same data and observed that the 
principal route for traffic through Pinal County (serving in-county as 
well as out-of-county commuters) is Interstate 10, which bisects the 
western half of the county and connects metropolitan Phoenix (largely 
in Maricopa County) to the north with metropolitan Tucson (in Pima 
County) to the south. ADEQ cites traffic and commuting patterns as a 
factor supporting the exclusion of the eastern half of the county from 
the new nonattainment area. While EPA agrees that it is reasonable to 
distinguish between the eastern and western halves of the county, EPA 
believes that the data indicate that the entire western half of the 
county, and not a small portion of it, as the State recommends, should 
be redesignated to nonattainment. Thus, EPA finds that traffic and 
commuting patterns do not make a case for the state's recommendation, 
but rather lend support to the creation of a larger nonattainment area 
generally encompassing the western half of the County. See figure 3-17 
from the State's technical report, which shows much higher employment 
densities projections for year 2030 in the western half of the county 
than those in the eastern half but which also show higher employment 
densities east and south of the State's recommended boundaries (but 
still within the western half of the county).
    Meteorology. Generally, the analysis of meteorology looks to wind 
data for evidence that emissions originating from areas in certain 
locations relative to violating monitors may be more prone to 
contribute than emissions originating from sources located elsewhere. 
ADEQ's technical report describes the dynamics responsible for region-
wide weather patterns and the associated winds blowing across Arizona, 
as well as the frequent occurrence of ``drainage'' winds, which occur 
when large-scale weather influences wane. ADEQ describes how steep 
pressure gradients result from strong high pressure building over the 
western United States and low pressure to the east. As the high 
pressure builds, a steep pressure differential is created that causes 
strong winds over Arizona to entrain and transport dust from in-county 
and out-of-county sources. These can cause elevated PM10 
concentrations. ADEQ also notes however, that not all exceedances of 
the PM10 standard are wind-related and that stagnation 
conditions in the fall and winter occur when cold air and the absence 
of winds trap ambient PM10 in the lower atmosphere. ADEQ 
notes that the region of the county most impacted by stagnation 
conditions is the western agricultural basin.
    The State recommends including the agricultural basin region of the 
county where stagnation conditions are known to impact PM10 
concentrations. While we agree that the new nonattainment area should 
include the agricultural basin region where stagnation conditions 
occur, we find that the State's recommended boundaries do not in fact 
accomplish this. As shown on page 14 of the ADEQ's technical report, 
the agricultural basin region of the county, roughly defined based on 
tilling and harvesting emissions within the county, lies in the western 
half of the county, and also extends south of Interstate 10 towards the 
southern county line. Moreover, as discussed in the following 
paragraph, a review of available wind data supports the inclusion of 
areas to the south and east of the violating monitors (i.e., beyond the 
State's recommended boundaries) based on the prevalence of winds from 
the southeast quadrant.
    EPA has considered the information provided by ADEQ but also 
reviewed available wind data for Pinal County and finds that winds are 
similar throughout central and western Pinal County in that the 
predominant wind directions are from the southeast quadrant. See figure 
10 of EPA's TSD. (We note that winds blow out of the north and 
northwest far less frequently, making transport of PM10 from 
the metropolitan Phoenix area unlikely under most circumstances.) In 
this instance, the predominance of southeast winds support boundaries 
that extend south and east of the violating monitors because 
PM10 sources, including agricultural activities and unpaved 
roads, are found in those directions. EPA's recommended boundaries 
encompass the types of sources that are believed to cause or contribute 
to the monitored violations and that are located east and south of the 
violating monitors, whereas the State's recommended boundaries largely 
exclude these sources. See figure 2 (PM10 monitors, ADEQ's 
recommended nonattainment area boundary, and EPA's proposed 
nonattainment area boundary), figure 4 (Pinal County agriculture, 
cattle operations, and unpaved roads), and figure 5 (ADEQ's map 
illustrating the distribution of emissions in Pinal County) from EPA's 
TSD.
    Lastly, EPA recognizes that high wind events do occur in Pinal 
County, and that some of these events may result in monitored 
particulate matter exceedances that qualify as caused by exceptional 
events under EPA's exceptional events rule.\8\ However, as

[[Page 60685]]

ADEQ itself acknowledges, even if EPA were eventually to determine that 
all of the exceedances that ADEQ has flagged are caused by 
``exceptional events,'' the area would still clearly be in violation of 
the PM10 NAAQS.
---------------------------------------------------------------------------

    \8\ On March 22, 2007, EPA adopted a final rule, Treatment of 
Data Influenced by Exceptional Events, to govern the review and 
handling of certain air quality monitoring data for which the normal 
planning and regulatory processes are not appropriate. Under the 
rule, EPA may exclude data from use in determinations of National 
Ambient Air Quality Standard (NAAQS) exceedances and violations if a 
state demonstrates that an ``exceptional event'' caused the 
exceedances, and satisfies other criteria set forth by the rule. See 
72 FR 13560.
---------------------------------------------------------------------------

    Geography/Topography. The geography/topography factor evaluates 
physical features of the land that might have an effect on the airshed, 
and therefore, on the distribution of particulate matter over an area. 
In its technical report, ADEQ describes the topography of Pinal County 
in terms of a broad basin, low in elevation (roughly 1,200 feet in 
elevation), surrounded on all sides by mountain ranges. ADEQ finds that 
topographic considerations support the State's inclusion of the basin 
region of the county, which is characterized by open-ended valleys with 
few topographic barriers, within the recommended boundaries. 
Conversely, ADEQ finds that topographic considerations support the 
State's exclusion from the recommended boundaries of the eastern 
portion of the county, which is characterized by rough terrain and 
steep mountain ranges reaching over 7,000 feet in elevation.
    EPA too has considered topography and generally agrees with ADEQ's 
description of the topography of Pinal County. We believe that the 
various mountain ranges found on each side of the county inhibit 
transport of PM10 (which is largely crustal in composition--
see figure 6 of EPA's TSD) from outside the county to the violating 
monitors within the county. Within the county itself, we believe that 
the mountains in the eastern quarter of the county, which rise to 
approximately 6,000 feet near the eastern borders with Gila and Graham 
counties, inhibit intra-county transport from sources located in the 
eastern quarter to the violating monitors. See figure 11 of EPA's TSD. 
(The portion of the San Carlos Apache Reservation that lies within 
Pinal County is located in the eastern quarter of the county.)
    However, the existence of the steep mountain ranges in the eastern 
quarter of the County does not justify ADEQ's recommendation to exclude 
from redesignation a much larger section of the western half of the 
County. EPA believes that, taking other factors into account, the 
western half of the County, located in the basin region that features 
few topographic barriers, should be redesignated to nonattainment. 
Indeed, it is arguable that topography alone would lend support to 
redesignating a far larger area than EPA is proposing, one that would 
encompass the entire county, excepting only the eastern quarter. 
However, EPA believes that topography when evaluated in the context of 
the various other factors, supports redesignation of the western half 
of the county, rather than the much more restricted boundaries that 
ADEQ suggests.
    Jurisdictional Boundaries. The analysis of jurisdictional 
boundaries evaluates the planning and organizational structure of an 
area to determine if the implementation of controls in a potential 
nonattainment area can be carried out in a cohesive manner. ADEQ's 
technical report notes the absence of any certified metropolitan 
planning organization (MPO) for Pinal County and the exclusion of 
Indian country from the State's recommendation. As such, ADEQ concludes 
that the State's recommended boundaries maintain jurisdictional 
cohesiveness requiring no new institutional arrangements for 
accomplishing required tasks.
    EPA also considered the planning and organizational structure of 
the State of Arizona and Pinal County (cities, towns, and 
unincorporated areas), but also took into account Indian country, to 
ensure that the implementation of controls within the prospective 
nonattainment area could be carried out in a cohesive manner. ADEQ 
exercises overall jurisdiction over environmental programs in the State 
of Arizona (i.e., excluding Indian country). Under state law, ADEQ has 
the responsibility for preparing air quality attainment and maintenance 
plans in Pinal County. With respect to permitting and enforcement, the 
Pinal County Air Quality Control District (AQCD or ``District'') has 
jurisdiction over most types of stationary sources operating, or 
proposing to locate, within Pinal County, but state law retains ADEQ's 
statewide jurisdiction over certain types of stationary sources 
(smelters, refineries, coal-fired power plants, and agricultural 
operations). Neither ADEQ nor the District have jurisdiction within 
Indian country.
    In its technical report, ADEQ notes that five cities and towns 
(Casa Grande, Coolidge, Eloy, Florence, and City of Maricopa), as well 
as a portion of a sixth (Queen Creek) are located in central and 
western Pinal County. ADEQ indicates that the incorporated boundaries 
of these municipalities have been taken into account in developing the 
nonattainment area boundaries. However, EPA's review of the 
incorporated boundaries of these municipalities (see, e.g., figure 2 of 
EPA's TSD) shows that the State's recommended boundaries omit portions 
of the City of Maricopa and Coolidge, and most of Florence and Eloy. In 
contrast, EPA's proposed nonattainment area boundaries encompass all of 
these cities and towns, where most of the county's population resides. 
Inclusion of entire cities and towns within the nonattainment area 
boundaries would facilitate attainment planning to the extent that such 
local governments will ultimately be relied upon for development and/or 
implementation of specific PM10 control measures.
    Level of Control of Emission Sources. The level of control factor 
looks at the emissions controls currently implemented in each area. As 
a general matter, most existing and proposed stationary sources within 
Pinal County (excluding Indian country) are subject to the generally 
applicable prohibitory rules and permitting requirements established by 
the Pinal County AQCD, or, in the case of certain types of stationary 
sources (smelters, refineries, coal-fired power plants, and 
agricultural operations), State prohibitory rules and permitting 
requirements established by ADEQ.
    Pinal County AQCD has established rules for dust abatement purposes 
that apply within a subarea of Pinal County established under state law 
(Arizona Revised Statutes section 49-541) and referred to as ``Area 
A.'' Within Pinal County, ``Area A'' generally refers to an area 
encompassing the Pinal County portions of Apache Junction and Queen 
Creek. Pinal County has also adopted a number of ordinances that are 
also intended to reduce dust generated within ``Area A.'' These include 
ordinances placing restrictions on residential fireplaces, leaf 
blowers, open burning, vehicle commute trips, and vehicle idling. For 
one township located within ``Area A,'' the township included in the 
Phoenix Area PM10 nonattainment area (i.e., Township 1 
north, range 8 east; referred to as ``Apache Junction''), Pinal County 
AQCD has adopted further dust abatement rules.\9\ The State's 
recommended boundaries include a portion, but not all, of ``Area A.'' 
In contrast, EPA's proposed boundaries for the new nonattainment area 
would encompass

[[Page 60686]]

all of ``Area A,'' thereby facilitating review and modification of 
these existing PM10 emissions controls within the broader 
SIP attainment planning context.
---------------------------------------------------------------------------

    \9\ The township referred to as Apache Junction would be 
unaffected by our proposed action and would remain part of the 
Phoenix planning area, which is designated as a ``serious'' 
PM10 nonattainment area.
---------------------------------------------------------------------------

    Conclusion. CAA section 107(d)(3)(C) provides that after notifying 
the Governor of State of its intent to redesignate an area, EPA shall 
promulgate the redesignation, if any, of the area or portion thereof, 
submitted by the Governor, ``making such modifications as EPA may deem 
necessary. * * *'' Pursuant to CAA section 107(d)(3), we have reviewed 
the State's recommendation (dated March 23, 2010) and related technical 
report (submitted on March 26, 2010).
    Both EPA and the State agree that sources outside of the county do 
not contribute to PM10 violations at the violating monitors 
within the county, and that sources in the eastern half of the county 
do not contribute to the violating monitors (which are concentrated in 
the central and western portions of the county). But while EPA and the 
State both use the nine-factor analysis for evaluation of the 
prospective nonattainment area boundaries, we reach quite different 
conclusions.
    As explained above, and more fully in EPA's TSD, EPA does not 
believe that the State's recommended boundaries encompass the full 
geographic area from which emissions-generating activities contribute 
to the monitored PM10 violations. More specifically, we 
believe that the Governor's recommended boundaries, which cut through 
municipalities and contiguous expanses of agricultural fields, exclude 
sources that have been identified as dominant sources of 
PM10 and that are contributing to elevated levels of 
PM10 at violating monitors.
    We believe that our proposed boundaries, which are defined as all 
land geographically located within Pinal County west of the north-south 
line defined by the boundary between Townships 10E and 11E, but 
excluding TON's main reservation and excluding the existing Apache 
Junction portion of the existing Phoenix PM10 nonattainment 
area, encompass the areas in which PM10 violations are being 
monitored, as well as the areas that contribute to the monitored 
violations, and that they are thus consistent with the definition of 
nonattainment areas in CAA section 107(d)(1)(A). Our conclusion is 
based on EPA's analysis of the factors as set forth in the body of this 
document and in further detail in the TSD. In sum, we base our proposed 
boundaries on the following considerations: (1) Monitored violations 
occur in the west, central and northern portions of the western half of 
the county, not in the eastern half (i.e., outside of existing 
PM10 nonattainment areas); (2) the emissions from 
agricultural operations, feedlots, dairies, and other cattle 
operations, as well as roads, are concentrated in the western half of 
the county; (3) population densities are much greater in the western 
half of the county than in the eastern half and growth is expected to 
be concentrated primarily along the Interstate corridors that extend 
through the western half of the county; (4) Interstate 10, which 
connects Pinal County with the employment centers in metropolitan 
Phoenix and Tucson, bisects the western half of Pinal County; (5) 
predominant southeasterly winds support inclusion of PM10 
sources in areas to the south and east of the violating monitors; (6) 
the western half of Pinal County encompasses the incorporated 
boundaries of all of the cities in Pinal County (Apache Junction, Casa 
Grande, Coolidge, Eloy, Maricopa), as well as the larger towns 
(Florence and Queen Creek) thereby potentially facilitating 
implementation of future control measures; and (7) dust abatement 
measures already in effect in ``Area A'' (within Pinal County) can 
readily be applied, as necessary and appropriate, throughout the other 
portions of the western half of Pinal County. A map comparing the 
State's recommended boundaries to EPA's proposed boundaries is included 
as figure 2 in our TSD.
    EPA therefore deems it necessary and appropriate to propose 
boundaries that differ from the State's recommended boundaries and that 
we believe better satisfy air quality data, planning, control and other 
air-quality-related considerations. CAA Section 107(d)(3). Under CAA 
section 107(d)(3)(C), EPA must notify the State whenever EPA intends to 
modify State recommendations concerning boundaries for areas to be 
redesignated, at least 60 days prior to EPA promulgation of final 
redesignations. EPA intends to notify the State of Arizona of our 
proposed action soon after this notice is signed.

V. EPA's Review of Recommendations From Affected Indian Tribes

    Ak-Chin Indian Community. The Ak-Chin Indian Community is located 
in western Pinal County, and is included in the existing ``rest of 
state'' unclassifiable area for PM10. The Ak-Chin Indian 
Community does not operate a PM10 monitoring site, but lies 
in proximity to several PM10 monitoring sites that do 
monitor violations of the PM10 NAAQS (e.g., the Maricopa and 
Cowtown sites). In a letter dated September 2, 2010 the Ak-Chin Indian 
Community responded to EPA's December 30, 2009 letter concerning the 
PM10 designation of Pinal County with a recommendation that 
the Ak-Chin lands be designated attainment/unclassifiable. We have 
offered formal consultation to the Ak-Chin Indian Community and have 
decided to defer action on redesignation of the Ak-Chin Indian 
Community for PM10 to allow time for formal consultation to 
occur and for further consideration of this issue as part of that 
process. If in the future EPA decides to take action to redesignate the 
Ak-Chin Indian Community, the Agency will do so in a separate 
rulemaking.
    Gila River Indian Community. The Gila River Indian Community (GRIC) 
is a community located on 374,000 acres in south central Arizona. 
Approximately one-third of GRIC lies within Maricopa County and two-
thirds lies within Pinal County. The Maricopa County portion of GRIC is 
included in the Phoenix Area PM10 nonattainment area. The 
Pinal County portion of GRIC is included in the existing ``rest of 
state'' unclassifiable area for PM10. GRIC operates a 
PM10 monitoring site in the Pinal County portion of its 
lands and GRIC's monitor has recorded a number of PM10 
exceedances. See table 1 above in this document. However, GRIC has 
flagged a significant number of these exceedances as caused by 
``exceptional events'' under EPA's exceptional event rule (50 CFR 
50.14), and EPA has not yet taken action to determine whether any of 
these data should be excluded on that basis from consideration in a 
redesignation action. In October 2009, EPA approved GRIC's application 
for treatment in the same manner as a state for the purposes of CAA 
section 107(d) air quality designations. More recently, we proposed 
approval of GRIC's submitted tribal implementation plan. See 75 FR 
48880, August 12, 2010.
    As noted above, on December 30, 2009, EPA notified GRIC that the 
PM10 designation for Pinal County should be revised. GRIC 
first indicated orally, and later confirmed in a letter dated May 27, 
2010, that the community would not be making a recommendation for 
PM10 until formal consultation is conducted. By letter dated 
April 30, 2010, EPA responded to GRIC's oral request with an offer of 
formal consultation. As with the Ak-Chin Indian Community, we have 
decided to defer action on a decision whether to redesignate GRIC to 
allow time for formal consultation to occur and for further 
consideration of this issue as part of that process. In

[[Page 60687]]

addition, the deferral for GRIC will provide EPA with the time 
necessary to address the exceptional events issues. If in the future 
EPA decides to undertake redesignation of the Pinal County portion of 
the Gila River Indian Community, the Agency will do so in a separate 
rulemaking.
    San Carlos Apache Tribe. The San Carlos Apache Reservation extends 
over a portion of eastern Pinal County, as well as portions of Gila and 
Graham counties. A section of the Pinal County portion of the San 
Carlos Apache Reservation lies in the existing Hayden PM10 
nonattainment area. The rest of the Pinal County portion of the 
reservation is located within the ``rest of state'' unclassifiable area 
for PM10. The San Carlos Apache Tribe did not respond to 
EPA's December 30, 2009 letter concerning the PM10 
designation in Pinal County.
    For the reasons discussed in section IV of this document, we 
believe that emissions sources in the eastern half of Pinal County do 
not contribute to violations monitored in the western half of the 
county, and thus are proposing only that the western half of the county 
(excluding TON's main reservation and the Apache Junction portion of 
the existing Phoenix PM10 nonattainment area) be 
redesignated to nonattainment. Given that the San Carlos Tribe's Indian 
country extends only into far eastern Pinal County, we propose to 
retain the Tribe's current designations for the PM10 
standard (i.e., a portion remains in the existing Hayden 
PM10 nonattainment area, and a portion remains in the 
existing ``rest of state'' unclassifiable area).
    Tohono O'odham Nation. The Tohono O'odham Nation (TON) extends over 
portions of Pima, Maricopa and Pinal counties. TON's main reservation 
covers much of southwestern Pinal County and extends over portions of 
Pima and Maricopa counties. TON's lands also include a small area 
(approximately 25 acres), known as Florence Village, which is located 
approximately two miles west of the town of Florence in central Pinal 
County, and a 3,200-acre parcel east of the main reservation called San 
Lucy Farm. With the exception of a small portion of TON included within 
the existing Rillito PM10 nonattainment area (which is 
located in Pima County), TON is included in the ``rest of state'' 
unclassifiable area for PM10.
    In a letter dated February 11, 2010, TON responded to EPA's 
December 30, 2009 letter concerning the PM10 designation in 
Pinal County with a recommendation that the TON land within Pinal 
County be designated attainment/unclassifiable for PM10. 
With respect to the main reservation in southwestern Pinal County, we 
agree with TON's recommendation and are proposing a nonattainment area 
with boundaries that exclude TON's main reservation. We agree with 
TON's recommendation in this regard because (1) the closest violating 
monitors (Stanfield and Casa Grande) are located in the midst of the 
county's agricultural basin, well north of TON's main reservation; (2) 
the types of emissions sources believed to be responsible for the 
PM10 violations, such as agricultural operations, feedlots, 
and dairies (see figure 4 of EPA's TSD), as well as roads, are largely 
absent from TON; (3) the population density of TON is very low, and is 
an order of magnitude less than the average population density of Pinal 
County (see table 5 of EPA's TSD); and (4) TON is a separate sovereign 
not subject to state or county jurisdiction thereby complicating 
planning and implementation issues. We conclude therefore that TON's 
main reservation is not contributing to the PM10 violations 
monitored elsewhere in Pinal County and propose to exclude TON from the 
new nonattainment area. Under this proposal, the designation of TON's 
main reservation would remain unchanged, i.e., it would remain part of 
the ``rest of state'' unclassifiable area for PM10.
    As to Florence Village and San Lucy Farm, EPA is deferring 
redesignation to allow for further consultation with TON. If in the 
future EPA decides to take action to redesignate TON's Florence Village 
and San Lucy Farm, the Agency will do so in a separate rulemaking.

VI. Proposed Action and Request for Public Comment

    Pursuant to section 107(d)(3) of the Clean Air Act and based on our 
evaluation of air quality data, planning, control and other air-
quality-related information and considerations, and our review of the 
Governor's recommendation, EPA is proposing to redesignate from 
``unclassifiable'' to ``nonattainment'' an area generally covering the 
western half of Pinal County, Arizona, for the 1987 PM10 
NAAQS and therefore to revise the boundaries of the existing ``rest of 
state'' unclassifiable area. EPA's proposal to establish this new 
PM10 nonattainment area, referred to as ``West Pinal,'' is 
based on numerous recorded violations of the PM10 standard 
at various monitoring sites within the county, and on the other grounds 
set forth in this document and in the TSD.
    EPA's proposed boundaries for the nonattainment area would 
encompass all of the area recommended by the State of Arizona, but 
would extend further to the east and south, and to a lesser degree, to 
the north and west. EPA's proposed boundaries would encompass all land 
geographically located within Pinal County west of the north-south line 
defined by the boundary between Townships 10E and 11E, but excluding 
TON's main reservation and excluding the Apache Junction portion of the 
existing Phoenix PM10 nonattainment area. If finalized as 
proposed, the new ``West Pinal'' PM10 nonattainment area 
would be classified as ``moderate'' by operation of law. See figure 2 
of EPA's TSD for a map showing EPA's proposed boundaries.
    We believe that our proposed boundaries as described above 
encompass the areas in which PM10 violations are being 
monitored, as well as the areas that contributes to the monitored 
violations, and that they are thus consistent with the definition of 
nonattainment areas in CAA section 107(d)(1)(A). Our conclusion is 
based on EPA's analysis of the factors as set forth in the body of this 
document and in further detail in the TSD. We find support for our 
proposed boundaries based on the following considerations: (1) 
Monitored violations occur in the west, central and northern portions 
of the western half of the county, not in the eastern half (i.e., 
outside of existing PM10 nonattainment areas); (2) the 
emissions from agricultural operations, feedlots, dairies, and other 
cattle operations, as well as roads, are concentrated in the western 
half of the county; (3) population densities are much greater in the 
western half of the county than in the eastern half and growth is 
expected to be concentrated primarily along the Interstate corridors 
that extend through the western half of the county; (4) Interstate 10, 
which connects Pinal County with the employment centers in metropolitan 
Phoenix and Tucson, bisects the western half of Pinal County; (5) 
predominant southeasterly winds support inclusion of PM10 
sources in areas to the south and east of the violating monitors; (6) 
the western half of Pinal County encompasses the incorporated 
boundaries of all of the cities in Pinal County (Apache Junction, Casa 
Grande, Coolidge, Eloy, Maricopa), as well as the larger towns 
(Florence and Queen Creek) thereby potentially facilitating 
implementation of future control measures; and (7) dust abatement 
measures already in effect in ``Area A'' (within Pinal County) can 
readily be applied, as necessary and appropriate, throughout the other

[[Page 60688]]

portions of the western half of Pinal County.
    EPA has determined that activities occurring on the main Tohono 
O'odham Nation (TON) reservation are not causing or contributing to 
violations occurring in Pinal County and we are therefore proposing to 
exclude the main TON reservation from the new nonattainment area. San 
Carlos Apache lands, which are located in the eastern quarter of the 
county, would be excluded from the proposed nonattainment area along 
with the rest of the eastern half of the county. EPA is deferring its 
decision regarding redesignation of the Ak-Chin and Gila River Indian 
Community lands, as well as TON's Florence Village and San Lucy Farm, 
pending consideration of issues unique to tribal lands, completion of 
formal consultation with the tribal governments, and (in the case of 
GRIC) consideration of exceptional events flags. The existing Phoenix 
PM10 nonattainment area (including the Apache Junction 
portion of western Pinal County) would be unaffected by this action.
    Areas redesignated as nonattainment, as proposed herein, are 
subject to the applicable requirements of part D, title I of the Act 
and will be classified as moderate by operation of law (see section 
188(a) of the Act). Within 18 months of the redesignation, the State is 
required to submit to EPA an implementation plan for the area 
containing, among other things, the following requirements: (1) 
Provisions to assure that reasonably available control measures 
(including reasonably available control technology) are implemented 
within 4 years of the redesignation; (2) a permit program meeting the 
requirements of section 173 governing the construction and operation of 
new and modified major stationary sources of PM10; (3) 
quantitative milestones which are to be achieved every 3 years until 
the area is redesignated attainment and which demonstrates reasonable 
further progress, as defined in section 171(1), toward timely 
attainment; and (4) either a demonstration (including air quality 
modeling) that the plan will provide for attainment of the 
PM10 NAAQS as expeditiously as practicable, but no later 
than the end of the sixth calendar year after the area's designation as 
nonattainment, or a demonstration that attainment by such date is 
impracticable (see, e.g., section 188(c), 189(a), 189(c), and 172(c) of 
the Act). We have issued detailed guidance on the statutory 
requirements applicable to moderate PM10 nonattainment areas 
[see 57 FR 13498 (April 16, 1992), and 57 FR 18070 (April 28, 1992)].
    If we finalize the proposed redesignation, the State would also be 
required to submit contingency measures (for the new PM10 
nonattainment area), pursuant to section 172(c)(9) of the Act, which 
are to take effect without further action by the State or EPA, upon a 
determination by EPA that an area has failed to make reasonable further 
progress or attain the PM10 NAAQS by the applicable 
attainment date (see 57 FR 13510-13512, 13543-13544). The EPA is 
proposing to establish a deadline for submission of contingency 
measures as called for in section 172(b) of the Act to coincide with 
the submittal date requirement for the other SIP elements discussed 
above, i.e., 18 months after redesignation. Lastly, any new 
PM10 nonattainment area would be subject to EPA's general 
and transportation conformity regulations (40 CFR part 93, subparts A 
and B) upon the effective date of redesignation. See section 176(c) of 
the Act.
    We will accept comments from the public on this proposal for thirty 
days from the date of publication of this notice, and will consider any 
relevant comments in taking final action on today's proposal.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866, Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), EPA has 
determined that the redesignation to nonattainment proposed today, as 
well as the establishment of SIP submittal schedules, would result in 
none of the effects identified in Executive Order 12866, section 3(f). 
Under section 107(d)(3) of the Act, redesignations to nonattainment are 
based upon air quality considerations. The proposed redesignation, 
based upon air quality data showing that West Pinal is not attaining 
the PM10 standard and upon other air-quality-related 
considerations, does not, in and of itself, impose any new requirements 
on any sectors of the economy. Similarly, the establishment of new SIP 
submittal schedules would merely establish the dates by which SIPs must 
be submitted, and would not adversely affect entities.

B. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 
Burden is defined at 5 CFR 1320.3(b).

C. Regulatory Flexibility Act

    Under the Regulatory Flexibility Act (RFA), 5 U.S.C. 601 et. seq., 
a redesignation to nonattainment under section 107(d)(3), and the 
establishment of a SIP submittal schedule for a redesignated area, do 
not, in and of themselves, directly impose any new requirements on 
small entities. See Mid-Tex Electric Cooperative, Inc. v. FERC, 773 
F.2d 327 (DC Cir. 1985) (agency's certification need only consider the 
rule's impact on entities subject to the requirements of the rule). 
Instead, this rulemaking simply proposes to make a factual 
determination and to establish a schedule to require the State to 
submit SIP revisions, and does not propose to directly regulate any 
entities. Therefore, pursuant to 5 U.S.C. 605(b), EPA certifies that 
today's proposed action does not have a significant impact on a 
substantial number of small entities within the meaning of those terms 
for RFA purposes.

D. Unfunded Mandates Reform Act

    Under Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 
Public Law 104-4, EPA has concluded that this proposed rule is not 
likely to result in the promulgation of any Federal mandate that may 
result in expenditures of $100 million or more for State, local or 
tribal governments in the aggregate, or for the private sector, in any 
one year. It is questionable whether a redesignation would constitute a 
Federal mandate in any case. The obligation for the state to revise its 
State Implementation Plan that arises out of a redesignation is not 
legally enforceable and at most is a condition for continued receipt of 
federal highway funds. Therefore, it does not appear that such an 
action creates any enforceable duty within the meaning of section 
421(5)(a)(i) of UMRA (2 U.S.C. 658(5)(a)(i)), and if it does the duty 
would appear to fall within the exception for a condition of Federal 
assistance under section 421(5)(a)(i)(I) of UMRA (2 U.S.C. 
658(5)(a)(i)(I).
    Even if a redesignation were considered a Federal mandate, the 
anticipated costs resulting from the mandate would not exceed $100 
million to either the private sector or State, local and tribal 
governments. Redesignation of an area to nonattainment does not, in 
itself, impose any mandates or costs on the private sector, and thus, 
there is no private sector mandate within the meaning of section 421(7) 
of UMRA (2 U.S.C. 658(7)). The only cost resulting from the 
redesignation itself is the cost to the State of Arizona of developing, 
adopting, and submitting any necessary

[[Page 60689]]

SIP revision. Because that cost will not exceed $100 million, this 
proposal (if it is a federal mandate at all) is not subject to the 
requirements of sections 202 and 205 of UMRA (2 U.S.C. 1532 and 1535). 
EPA has also determined that this proposal would not result in 
regulatory requirements that might significantly or uniquely affect 
small governments because only the State would take any action as 
result of today's rule, and thus the requirements of section 203 (2 
U.S.C. 1533) do not apply.

E. Executive Order 13132, Federalism

    Executive Order 13132 requires EPA to develop an accountable 
process to ensure ``meaningful and timely input by State and local 
officials in the development of regulatory policies that have 
federalism implications.'' This rule will 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, because it merely proposes to redesignate an 
area for Clean Air Act planning purposes and does not alter the 
relationship or the distribution of power and responsibilities 
established in the Clean Air Act. Thus, the requirements of section 6 
of the Executive Order do not apply to this rule.

F. Executive Order 13175, Coordination With Indian Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, November 9, 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.'' The area proposed for 
redesignation does not yet include, and EPA is deferring action on the 
Ak-Chin Indian Reservation, the Pinal County portion of the Gila River 
Indian Reservation, and TON's Florence Village and San Lucy Farm. In 
formulating its further action on these areas, EPA has been 
communicating with and plans to continue to consult with 
representatives of the Tribes, as provided in Executive Order 13175. 
Accordingly, EPA has addressed Executive Order 13175 to the extent that 
it applies to this action.

G. Executive Order 13045, Protection of Children From Environmental 
Health Risks and Safety Risks

    This proposed rule is not subject to Executive Order 13045 
(``Protection of Children from Environmental Health Risks'') (62 FR 
19885, April 23, 1997), because it is not an economically significant 
regulatory action based on health or safety risks.

H. Executive Order 13211, Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This rule is not subject to Executive Order 13211, ``Actions 
Concerning Regulations That Significantly Affect Energy Supply, 
Distribution, or Use'' (66 FR 28355, May 22, 2001) because it is not a 
significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12 of the National Technology Transfer and Advancement Act 
(NTTAA) of 1995 requires Federal agencies to evaluate existing 
technical standards when developing a new regulation. The EPA believes 
that the requirements of NTTAA are inapplicable to this action because 
they would be inconsistent with the Clean Air Act.

J. Executive Order 12898, Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Today's action proposes to redesignate an area to nonattainment for 
an ambient air quality standard. It will not have disproportionately 
high and adverse effects on any communities in the area, including 
minority and low-income communities.

List of Subjects in 40 CFR Part 81

    Environmental protection, Air pollution control, Intergovernmental 
relations, National parks, Particulate Matter, Wilderness areas.

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

    Dated: September 21, 2010.
Jared Blumenfeld,
Regional Administrator, Region IX.
[FR Doc. 2010-24683 Filed 9-30-10; 8:45 am]
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