### Response to Comments

on the Proposed Action to Redesignate West Pinal County to Nonattainment

for the

1987 24‐hour PM 10 

### National Ambient Air Quality Standard

Office of Air Planning

Air Di ision Environmental Protection Agency – Region 9 v

May 2012ii List of Acronyms and Abbreviations

ADEQ :  A nmental Quality rizona Department of Enviro

Ak

­ C hin : Ak‐Chin Indian Community

APS : Ar izona Public Service Company

AZM teorological Network ET :  Arizona Me

CAA :  Clean Air Act

EPA : otection Agency United States Environmental Pr

GRIC :  G ila River Indian Community

NAA ty standard QS :  national ambient air quali

NEI :  n ational emissions inventory

PCAQ :  Pinal County Air Quality Control District

PM 1 smaller in size 0 :  particulate matter 10 microns and

RTC :  respo ument nse to comments doc

TON :  Tohono O’odham Nation

TSD :  technical support documentiii Response to Comments on the Proposed Action to Redesignate West Pinal County to Nonattainment

for the 1987 24

­ hour PM nt Air Quality Standard 10 National Ambie

Table of Contents

I.  Introduction and Background

omments Received on the Proposed Action II.  Response to C

III.  Final Action

V.  List of Comment Letters Received I1 R esponse to Comments on the Proposed Acti on to Redesignate West Pinal County to

M 10 National Ambient Air Quality Standard Nonattainment for the 1987 24-hour P



### I. I NTRODUCTION AND 

### B ACKGROUND

Pursuant to section 107(d)(3) of the Clean Air Act (CAA), the E nvironmental Protection Agency (EPA) 1 may notify the governor of any state that available informatio n indicates that the designation of any area should be revised.  Based on m onitoring data that indicated persistent violations of the 1987 24‐hour national ambient air quality standard (NAAQS) for particulate matter 10 microns and smaller in size (PM 10 ), EPA notified the Governor of

Arizona and tribal leaders for t he Ak‐Chin Indian Community (Ak ‐Chin), the Gila River Indian Community (GRIC), the San Carlos Apache Tribe, and the T ohono O’odham Nation (TON) that it was initiating the process to redesignate to nona ttainment areas that were violating the standard, along with any nearby areas that could be causing or contributing to

hose violations. t 2 EPA requested recommendations f or the redesignation by Februa ry 11, 2010, consistent with the timelines set out in the CAA.

The Governor of Arizona responded to EPA’s notification that th e PM 10 designation of Pinal County, and any nearby areas tha t might be contributing to viol ations in Pinal County, should be revised, with a recommendation for a partial‐county n onattainment area. 3 The Governor’s letter was followed by a letter from the Arizona Dep artment of Environmental Quality (ADEQ) 4 transmitting Arizona’s justific ation for its recommended bound ary (herein referred to as the “technical report”).

The TON 5 and the Ak‐Chin 6 responded to EPA’s letter concerning the PM 10 designation in Pinal County with recommendatio ns that their lands be designate d

ttainment/unclassifiable for PM 10 . The San Carlos Apache Tribe and GRIC did not submit a recommendations.

After reviewing the recommendations we received and evaluating air quality data, planning, control and other air‐ quality‐related considerations, EPA proposed boundaries

that differed from the State’s r ecommended boundaries and that we believed better met the provisions of  CAA Section 107(d)(3). See 75 FR 60680, Octo ber 1, 2010. As explained

1 Throughout this document, the terms “we,” “us,” and “our” mea n U.S. EPA.

2 In a letter dated October 14, 2009, EPA notified the State of Arizona that the PM 10 designation in Pinal

C ounty should be revised. EPA no tified the tribal leaders of th e Ak‐Chin Indian Community, Gila River Indian Community, San Carlos Apache Tribe, and Tohono O’odham Nation b y letters dated December 30, 2009.

3 Letter from Jan Brewer, Governo r of Arizona, to Jared Blumenf eld, Regional Administ rator, EPA Region 9, dated March 23, 2010.

4 aura Yoshii, Letter from Benjamin H. Grumble s, Director, Arizona Departmen t of Environmental Quality, to L Acting Regional Administrator, U .S. EPA Region 9 (March 26, 201 0).

5 Letter from Ned Norris Jr., Chai rperson, Tohono O’odham Natio n to Jared Blumenfeld, Regional Administrator, U.S. EPA Region 9 (February 11, 2010).

6 Letter from Louis J. Manuel, Jr., Chairman, Ak‐Chin Indian Community, to Jared Blumenfeld, Regional
Administrator, U.S. EPA Re gion 9 (September 2, 2010).2 in our proposal, and more fully i n our technical support docume nt 7 (TSD), EPA concluded that the State’s recommended boundaries do not encompass the full geographic area from which emissions‐generating activities contribute to the monitor ed PM 10 violations. EPA proposed to redesignate from “un classifiable” to “nonattainment ” an area generally covering the western half of Pinal County, Arizona, for the 198 7 PM 10 NAAQS and therefore

to revise the boundaries of the existing “rest of state” unclas sifiable area.  We proposed to defer designation of the Ak‐Chin and GRIC lands, along with tho se TON lands located within the proposed nonattainment area, pending completion of formal c onsultation with the

ribes. See Figure 1 for a compa rison of ADEQ’s recommended boundaries for the West t
Pinal PM 10 nonattainment area with EPA’s fi nal boundaries for the area.

This response to comments docume nt (RTC) provides EPA’s full responses to the comments received on the October 1, 2010 proposed rulemaking. EPA received adverse

comment on the southern and easte rn boundaries of our proposed nonattainment area.

Based on our consideration of th e comments, including the build ing permit data provided by Pinal County that documents t he extent to which the national recession has slowed growth in Pinal County, and on further review of the geographic distribution of sources of

PM 10 , EPA has reduced the size of th e nonattainment area relative t o the area that EPA proposed as nonattainment from approximately 2,060 square miles to approximately 1,325

quare miles, which represents a reduction of approximately 735 square miles (or about s 36%).

The final boundaries for the non attainment area encompass all o f the area recommended by the State of Arizona, but extend farther to the east, west, and south. EPA is modifying its proposed boundary to exclude a p ortion of the Sonoran Desert Na tional Monument (including the Table Top Wildern ess Area), the Tonto National F orest and Superstition Wilderness Area, the Ironwood Forest National Monument, and cer tain less‐developed

areas of the eastern and souther n portions that we included in the proposed nonattainment

area.  Table 1 below identifies (by township) the portion of Pinal County, Arizona that EPA has designated as not attaining the 1987 24‐hour PM 10 NAAQS and compares that area with the recommendation submitted by A DEQ. Figure 1 illustrates the information from table 1. We were persuaded to revise our proposed boundary by our review of satellite imagery, maps of source locations, and ADEQ’s maps illustrating emissions estimates by township, which together illuminate land use and emissions. In certain ar eas (such as Florence, Eloy, Picacho Peak, and lands to the s outh of Interstate 8), the final boundary extends beyond the State’s recommended boundary. This was done to include areas th at, based on the location

of sources of PM 10 emissions, meteorological data that indicate winds from the so utheast ransport emissions to violating monitors, and topographic info rmation showing a lack of t geographic barriers, are contributing to air quality at violati ng monitors.

Figure 2 compares EPA’s proposed boundaries for the West Pinal PM 10 nonattainment area

with EPA’s final boundaries for t he area, and Figure 3 shows EP A’s final boundaries for the

7 Pinal County, Arizona – Area Redesignation for the 1987 24‐hou r PM 10 National Ambient Air Quality Standard. Technical Support D ocument, September 21, 2010.3 W est Pinal PM 10 nonattainment area in relation to land use and emissions sources within

nd near the new nonattainment area. a

Table 1

. Comparison of Townships Included Wi thin ADEQ’s Recommended Boundaries

for the West Pinal PM 10 Nonattainment Area With Thos e Included Within EPA’s Final

Boundaries for the Area 8

Arizona Recommended

Nonattainment Area within Pinal County EPA’s Final Designated

Nonattainment Area within Pinal County – “West Pinal”
T1S, R8E;
T2S, R8E;
T3S, R7E – R8E; T4S, R3E – R4E (excluding all lands

within the Gila River Indian and AkChin Indian Communities); T4S, R8E (excluding all lands within the Gila River Indian Community);

T5S, R3E – R8E (excluding all lands

within the Gila River and Ak-Chin Indian Communities);
T6S, R3E – R8E; T7S, R3E – R8E, Sections 1-6. T1S, R8E;
T2S, R8E;
T3S, R7E – R9E; T4S, R2E – R4E (excluding all lands

within the Gila River Indian and Ak-Chin Indian Communities); T4S, R8E – R10E (excluding all lands

within the Gila River Indian Community); T5S, R2E – R10E (excluding all lands

within the Gila River Indian and Ak-Chin Indian Communities);
T6S, R2E – R8E; T7S, R2E – R8E (excluding a portion

of the Sonoran Desert National Monument, including all of the Table Top Wilderness Area and all

lands within the Tohono O’odham Nation); T8S, R6E – R9E (excluding all lands

within the Tohono O’odham Nation); T9S, R7E – R10E (excluding all lands

within the Tohono O’odham Nation).

8 Table 1 provides general bounda ry information and was develop ed for ease of comparison with ADEQ’s recommended boundaries. H owever, the precise delineation of the final West Pinal PM 10 nonattainment area boundaries are set forth at the back of EPA’ s Final Rule.Figure 1 – Comparison of ADEQ’sRecommended Boundaries for theWest Pinal PM10Nonattainment Area with EPA’s Final Boundaries forthe Area4Figure 2 – Comparison of EPA’s Proposed Boundaries for the WestPinal PM10Nonattainment Area with EPA’s Final Boundaries for the Area5Figure 3 – EPA’s Final Boundaries for the West Pinal PM10Nonattainment Area With Land Use and Emissions Source Information67 as That Do Not Have Violating Monitors

Comment (2): Most commenters objected to the inclusion in the nonattainmen t area of

locations that have monitors that do not themselves show violat ions of the standard. Pinal County and others argued that the current monitoring data do no t justify the inclusion of the southern portion of the coun ty in the nonattainment area.  Some commenters believe 

### I I. R ESPONSE TO 

### C OMMENTS 

### R ECEIVED ON 

### P ROPOSED 

### A CTION

G eneral Comm ent

Comment (1) :  EPA received 11 comments on the proposal. No commenters disa greed with the need to redesignate a p ortion of Pinal County nonattainment for the 1987 24‐hour

PM 10 NAAQS. Most commenters, however, believe the nonattainment are a should be smaller than that proposed by EP A.  ADEQ requested that EPA rec onsider its proposed boundaries for the Pinal County PM 10 nonattainment area, and stated its belief that Arizona’s initial boundary recommendation is consistent with EP A guidance and of

sufficient size to address source s contributing to NAAQS violat ions measured in northwest Pinal County.  ADEQ believes that EPA should give more credence to ADEQ and Pinal County in determining the reason ableness of the boundaries. Pin al County believes that EPA has not justified an expanded PM 10 nonattainment area in southern Pinal County. The City of Casa Grande, Arizona Pub lic Service Company (APS), the Arizona Cotton Growers Association, the Arizona Farm Bu reau Federation, the Pinal Coun ty Farm Bureau, and a citizen supported the State’s nonattainment area boundary desig nation for PM 10 and

believe that the State’s boundar y meets all of the criteria required under the CAA. The Central Arizona Irrigation and D rainage District does not belie ve that EPA has fully considered the adjustments made as a result of Arizona’s public participation process that resulted in a more appropriate bo undary recommendation. The citizen commented that

PA’s extension of the boundary south to the county line is not justified. The Sierra Club upported EPA E

s ’s proposed boundaries.

Response (1) :  As described in detail below, based on our consideration of the comments,

EPA has reduced the eastern and southern extent of the proposed nonattainment area.  The

final boundaries for the new non attainment area encompass all o f the area recommended by the State of Arizona, but exte nd farther to the east and sou th, though not as far as proposed. We are finalizing the western boundary as proposed. T he final nonattainment area boundary excludes the Super stition and Table Top Wildernes s areas, the Ironwood Forest National Monument, and ce rtain less‐developed areas of t he eastern and southern portions of the proposed nonattainment area and reduces the siz e of the proposed nonattainment area by approximat ely 735 square miles. See Figur e 2 herein for a

omparison of EPA’s final and proposed boundaries for the West Pinal PM 10 nonattainment rea. See, for example, EPA’s responses to comments 9, 11, 12, 14 and 15. c

a

Air Quality Data

I nclusion of Are8 and should therefore be excluded from the nonattainment area.

The Arizona Game and Fish Department believes that rural, undev eloped, and largely uninhabited portions of the county are not violating the NAAQS or contributing to downwind exceedances, and should therefore be excluded from the nonattainment area.

he Arizona Farm Bureau Federation expressed concern that inclu ding areas that have not emonstrated compliance issues would dilute efforts to reach at tainment in Pinal County. that the nonattainment boundary should encompass only those are as where the data show

a violation of the PM 10 NAAQS.  Several commenters assert ed that it is unreasonable to conclude that an area that is not violating the standard is contributing to the PM 10 problem in an area that is violating the standard.   Commenters observe d that Eloy and Pinal Air Park monitors, which are located to the south of Arizona’s reco mmended nonattainment area, do not have any recorded violations. They argued that the se monitors would “register” transport and violate the standard if winds from the southeast were contributing to exceedances at the violating monitors.  The Arizona Cotton G rowers Association asserted

hat EPA’s reliance on wind trans port for inclusion of the sout hern and eastern areas is

a t fatally undercut by the record of clean d ta collected at the E loy monitor.

APS stated that ADEQ has recorded PM 10 violations at six of the twelve monitors located in Pinal County using 2006‐2008 monitoring data.  APS noted that t he six monitors are clustered together in the agricultural basin of western Pinal C ounty. They observed that the other monitors located in the eastern and southern portions of Pinal County have no recorded violations. APS argued that the aggregation of the vio lating monitors in the agricultural basin (the western region of Pinal County) clearly demonstrates that sources of

PM 10 located in the agricultural basin, not in the eastern or south ern region, are leading to he violations.  APS concluded that the State’s recommended boundary includes all of the t emissions sources that significantly contribute to the monitore d PM 10 violations.

The Arizona Farm Bureau Federati on stated that, based on 2006‐2 008 data, there are four

monitors that have exceeded the PM 10 NAAQS in Pinal County (Cowtown, Stanfield, Pinal County Housing, Combs School), a ll of which are located in the western portion of Pinal

ounty, and noted that these fou r monitors, as well as the moni tors in Casa Grande and C Coolidge, are included in the State’s recommended nonattainment area boundary.

A citizen supported the State’s r ecommended southern boundary b ecause the Eloy and Pinal Air Park monitors, which l ie to the south of the State’s nonattainment area boundary,

have not measured exceedances. T his citizen stated that both of these monitors are likely to

monitor PM 10 concentrations higher than those typically occurring in southern Pinal County because on‐road sources a re the highest emission category, both monitors are located next to I‐10, and the Eloy monitor is in a more urban a rea that has a higher road and population density than the rest of the area. From this inf ormation, the commenter inferred that, since the rest of the southern portion of the Co unty is less traveled, less densely populated, and has fewer roads than the areas surroundi ng the Eloy and Pinal Air

ark monitors, the southern port ion of the County is in compliance with the PM 10 NAAQS P

T

d9 Response (2): In establishing nonattainment a rea boundaries, EPA looks to t he definition of nonattainment found in CAA section 107(d)(1)(A)(i), which states that such areas include "any area that does not meet (or that contributes to am bient air quality in a nearby area that does not meet)" the NA AQS.  Thus, a location is subje ct to designation as

nonattainment if its emissions co ntribute to a NAAQS violation, even if it is not the main cause of violations, and even if it does not contribute to ever y measured violation.  It is not excluded simply because other lo cations contribute more, or bec ause there are some

violations to which the location does not contribute. But a con tiguous area within a few iles having emissions that can t ravel to a violating monitor s hould be included, even if its

e m contribution is smaller than that of locations n arer the monit or.

In order to violate the NAAQS for 24‐hour PM 10 , an air quality monitor must measure levels

of PM 10 greater than 150 micrograms per cubic meter ( μ g / m 3 ) more than once per year, on average, over a consecutive thr ee‐year period.  If the rate of expected exceedances is greater than 1, the monitor viol ates the air quality standard. The absence of a violation at the Eloy monitor does not preclu de the possibility of elevated levels of particulate in the vicinity of that monitor or the transport of particulate to ano ther area, even if levels are not severe enough and frequent enoug h to cause a violation at the E loy monitor itself.  For example, on August 16, 2008, the Eloy monitor registered a PM 10 level of 109 μ g / m 3 . On
March 26 and October 4, 2009 the Eloy monitor measured 120 and 153 μ g / m 3

, respectively. 9 As described more fully in our responses to comments 17‐20, pr evailing winds and the absence of topographic barriers provide evidence that emissions from

ources located in the south eas t portion of the nonattainment area, including Eloy, are s being transported to the violating monitors.

Finally, it should be noted that inclusion within the nonattain ment area does not predetermine the State's control strategy for the area; the deg ree of emission control needed for any given location will be decided in the context of the attainment demonstration developed by the S tate.  Further analysis may con firm that future PM 10 NAAQS violations can be prevented by application of controls on those sources the State

believes to be the main causes of the violations.

E

xceptional Eve nts

Comment (3): Two commenters noted that some of the measured exceedances ha ve been flagged as exceptional events 10 and suggested that EPA should not consider monitors to be

9 EPA’s regulations define an ex ceedance of the 1987 24‐hour PM 10 NAAQS as a daily value that is above the level of the 24‐hour standard (150μg/m 3 ) after rounding to the nearest 10 μg/m 3 , i.e., values ending in 5 or greater are to be rounded up and values ending i n 4 or less are to be rounded down. See 40 CFR 50 Ap ing o f 153μg/m 3 would be rounded to 150μg/m 3 , a d p. K, (a).  As a result , the October 4, 2009 read n would not be an exceed ance of the standard.

10 On March 22, 2007, EPA adopted a final rule, Treatment of Data Influenced by Exceptional Events, (EER), 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 da ta from use in determinations of NAAQS exceedances and violations if a state d emonstrates that an “exceptional event”10 violating if all of the exceedan ces have been flagged as except ional events.  ADEQ stated that, based on its analysis of t he most recent monitoring data, if flagged exceptional events

were excluded from the monitorin g record, four monitors (Casa G rande, Combs School, Coolidge, and Maricopa) would be attaining the standard.  The C ity of Casa Grande noted that the only exceedances measured within its city limits have been flagged by Pinal County

s exceptional events, and questioned EPA’s listing of monitors located in Casa Grande and a the surrounding areas as having violated the PM 10 standard.

ADEQ asserted that the purpose of boundary determinations is to enable the selection and implementation of control measur es to address stagnation‐ and w ind‐driven exceedances

that do not rise to the level of exceptional events because these events are defined as those that overwhelm implemented contr ol measures. Focusing on stagna tion‐ and wind‐driven

M 10 concentrations that could be re duced through an effective cont rol strategy supports pproval of Ari P

a zona’s recommended boundary.

Response (3): Based on the most recent certified data, seven monitors in Pinal County are violating the 24‐hour PM 10 standard.  Even if EPA had conc urred on all of the flags in th e 2009‐2011 time frame, three of Pinal County’s monitors (Stanfie ld, Pinal County Housing, and Cowtown) would still violate the 24‐hour PM 10 standard, as shown in Table 2, below. Furthermore, as explained above in response to comment (2), 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 tha t does not meet the NAAQS.  Thu s, even if EPA had concurred on all the exceptional event flags, and thereby reduced the num ber of violating monitors,

the boundaries for the nonattain ment area would be the same as finalized today because

emission sources in the areas su rrounding the monitors (Casa Gr ande, Coolidge, Combs School, and Maricopa) that would no longer be violating (i.e., assuming EPA concurrence of all of the flagged data) co ntribute to elevated PM 10 levels at the remaining violating

monitors.

caused the exceedances.  See 72 FR 13560.11Table2.ExpectedExceedancesatSelectedPM10MonitoringSitesWithinPinalCountySite NameAQS IDPM10Expected Exceedances2007-2009PM10Expected Exceedances2008-2010PM10Expected Exceedances2009-2011AllExceedancesIncludedExcludingFlaggedEventsAllExceedancesIncludedExcludingFlaggedEventsAllExceedancesIncludedExcludingFlaggedEventsCasa Grandea04-021-0001-104-021-0001-304.70002.700-6.4-0Apache Junctionb04-021-3002-104-021-3002-30-0-0-0-1.93.400Coolidge04-021-3004-1202020Mammothc04-021-3006-10000--Marana (Pinal Air Park)04-021-3007-1000000Stanfieldd04-021-3008-104-021-3008-316.417.84.04.03.09.702-12.7-1.3Combs School04-021-3009-317.63.13.105.80Maricopa04-021-3010-312.61.76.519.91Pinal County Housing(PCH)04-021-3011-104-021-3011-204-021-3011-36.55.915.6002.74.43.911.2002.710.5814.8002Riversidee04-021-3012-10000--Cowtown04-021-3013-104-021-3013-3112.9139.8112.9134.76586.16378.743.260.732.442.4Eloy04-021-3014-1000000aCasaGrandemonitor04‐021‐0001‐1(POC1)wasdiscontinuedinDecember2010.Monitor04‐021‐0001‐3(POC3)hasbeendesignatedasastateorlocalairqualitymonitoringstation(SLAMS)andservesastheprimarymonitorforthesite.bMonitor04‐021‐3002‐3(POC3),acontinuousmonitor(TEOM),wasinstalledattheApacheJunctionmonitoringsiteinAugust2012asaspecialpurposemonitor(SPM).AllPM10SPMsinPinalCountyareR&PTEOM1400a(A/B)continuousanalyzers,EPAdesignationnumberEQPM‐1090‐079,thatproducehourlydata.Quality‐assuredSPMsarecomparabletotheNAAQS.40CFR58.20(c)statesthat“[a]lldatafromaSPMusinganFRM,FEM,orARMwhichhasoperatedmorethan24monthsiseligibleforcomparisontotherelevantNAAQS...”subjecttocertainconditions.ExceptfortheApacheJunctionSPM,whichhasnotyetbeenoperatingformorethan24months,allSPMmonitorsinPinalCountyarecomparabletothe24‐hourPM10NAAQS.AlsoseetheAirQualityDatasectionofourTSD.cTheMammothmonitoringsitewasshutdowninMay2011;therefore,afullyearofdataisnotavailablefor2011.EPAapprovedthesiteshutdownonFebruary10,2012.dStanfieldmonitor04‐021‐3008‐1(POC1)wasdiscontinuedinDecember2009.Monitor04‐021‐3008‐1(POC3)hasbeendesignatedaSLAMSandservesastheprimarymonitorforthesite.eTheRiversidemonitoringsitewasshutdowninMay2011;therefore,afullyearofdataisnotavailablefor2011.EPAapprovedthesiteshutdownonFebruary10,2012.12 I mproved Air Q uality

Comment (4): ADEQ observed that the most recent air quality monitoring data show considerable progress in reducing 24‐hour PM 10 concentrations in Pin al County and that there has been a marked decrease in the frequency of exceedance s at all monitors in the

ounty, most notably at the Cowt own monitor.  ADEQ requested th at EPA consider these

mprovements C

i when making its f inal boundary determinations.

Response (4): EPA recognizes the improvement i n air quality illustrated by the declining

numbers of exceedances of the PM 10 NAAQS as compared to years past.  Recently certified data for 2011, however, show that while the Cowtown monitors co ntinue to record this downward trend, the number of ex pected exceedances (not taking into account flagged data) has slightly increased at most other monitors. As noted a bove, the certified data

indicate that seven monitors con tinue to violate the standard. Also see Response 3, above.

E missions Data

Inventory

Comment (5): ADEQ stated that the 2007 emissions inventory developed by AD EQ and Pinal County Air Quality Control District (PCAQ) is more accura te than the 2005 national emissions inventory (NEI) because the 2005 NEI includes emissio ns from several large‐ scale wildfires that occurred in 2002.  Accordingly, ADEQ belie ves EPA should have relied

n Arizona’s inventory for the p urpose of developing nonattainm ent area boundaries in inal County. o
P

Response (5): Wildfires accounted for on ly 2% of the primary PM 10 emissions in Pinal County, according to the 2005 NEI version 2.  As shown in Table 3 of EPA's TSD, the 2005

NEI version 2 indicates that t he main sources of primary PM 10 are paved and unpaved roads (collectively referred to a s “on‐road” emissions), agricu lture, and construction activities.  When reviewing emi ssions, EPA additionally considered ADEQ's preliminary

2007 PM 10 emissions inventory, which ADEQ used in its technical report.  While the NEI and ADEQ’s preliminary PM 10 emissions inventory disagr ee on the magnitude of the contribution of certain source categories, there is general agr eement between the two

egarding the source categories that contribute the most to the PM 10 levels in Pinal County. r See Tables 3 and 4 of EPA’s TSD.

These emissions inventories, together with results from speciat ion analyses projects conducted in 2003 and 2009, support EPA's conclusion that unpav ed and paved roads, construction, agriculture, concentrated animal feeding operatio ns, livestock dust, and some stationary sources are respo nsible for the elevated PM 10 levels in Pinal County.13 U ndeveloped la nds

Comment (6): The Arizona Game and Fish Depar tment commented that only area s where

credible emissions estimates are available should be included i n the nonattainment area. Because ADEQ had found it diffic ult to make credible emissions estimates for disturbed soils on undeveloped lands and windblown dust in its preliminar y inventory, the commenter believes that undeveloped lands should be excluded fr om the nonattainment

area.  The Sierra Club observed t hat undisturbed desert areas g enerate limited dust, but

ointed out that once the soil is disturbed, and often repeated ly disturbed, it can generate

nhealthful an p

u d dangerous levels of particulates.

Response (6): Based on the available data, and consistent with our guidance , EPA has established a nonattainment area that we believe encompasses th e areas in which PM 10 violations are being monitored, a s well as the areas that contr ibute to the monitored violations, consistent with the definition of nonattainment are as in CAA section 107(d)(1)(A). We have drawn the boundary to include sources of emissions that are contributing to the nonattainment problem and have revised our proposed boundary to better exclude areas with relatively low levels of emissions. The final boundary traces the county line in the west, the boundary between State lands and I ndian Country along the northern edge and in parts of th e south. In areas to the east a nd south, where following a jurisdictional boundary would res ult in the exclusion of areas that are contributing to violations or the inclusion of areas that are not contributing to the violations, we have used township and range lines to defi ne the boundary. Using this app roach, we minimize the inclusion of undeveloped lands. We also note that inclusion of an area within the boundary does not prejudge the need for controls or regulations that app ly to those lands. Arizona will be required to develop a pla n that results in the attainme nt of the air quality standard

for PM 10 , and the relative contribution of various sources and options for control will be considered in that process.  Tha t attainment plan will be subje ct to public review and

omment, both at the state level and again when EPA evaluates the plan for approval or isapproval as a revision to the Arizona state implementation p lan (SIP). c d

Geographic Dis tribution of Emissions Sources

Comment (7): A number of commenters objected to EPA’s previously proposed boundary because, in their view, sources of PM 10 emissions leading to monito red violations are in the western regions of Pinal County, not the east or south [of the Governor’s recommended

nonattainment area 16 ]. They argued that Governor Brewer’s boundary includes all of the

missions sources that contrib ute significantly to the PM 10 violations plus an adequate

uffer to the south and east. e b

16 Commenters referring t o the “eastern” and “southern” portions of Pinal County appear to be referring to

the areas to the east and south of the Governor’s recommended n onattainment boundary.  In our TSD and in this RTC, EPA’s references to th e eastern and we stern portions of Pinal County mean those portions of Pinal County that lie to the east and west of the eastern boundary of EPA’s proposed nonattainment area.14 see Response 2.

Comment (8): APS argued that the location of the violating monitors and th e PM 10 concentration readings show that the activities occurring in th e agricultural basin are the main cause of the violations. APS observed that ADEQ’s 2007 PM 10 Emission Inventory
shows that 95% of PM 10 emissions in Pinal County are a ssociated with on‐road vehicle travel, agriculture (tilling, harvesting, and animal feeding op erations), and construction. On‐road vehicle emissions (i.e., vehicle use on paved and unpaved roads) represent 83% of

the total PM 10 emissions. ADEQ’s analysis shows that a significant portion of on‐road

vehicle travel is in Western Pin al County where most of the cou nty agricultural activities are located. In addition, commuting pattern data along the I‐10 corridor in the Case Grande area shows that the majority of commuter traffic is to the nort h toward the Phoenix metropolitan area rather than so uth toward Tucson. From these d ata, APS concluded that Commenters pointed to differences in activity levels and the de gree of urbanization in

areas within and outside the Gov ernor’s recommended boundary an d argued that the preliminary emissions inventory determined that sources in the eastern and/or southern

egions of the county do not sig nificantly contribute to violat ions in other regions of the r county.

APS maintained that the State’s recommended boundary designatio n includes all of the emissions sources that significantly contribute to the monitore d PM 10 violations. It noted that ADEQ concluded that the eas tern and southern portions of the county are largely undeveloped, have a lower popula tion, and thus do not represent major sources of PM 10

. APS concurred with ADEQ’s conclu sion and believes that the sout hern and eastern areas, including the areas around Coolidge, Florence, and Eloy, should not be included within the

onattainment area boundary. They contend that these areas clearly do not contribute the

M 10 nonattain n
P ment issues in the west.

Response (7): Arizona’s preliminary PM 10 inventory and the 2005 NEI version 2, along with source apportionment studies, identify the sources that co ntribute to elevated

concentrations of PM 10 . These sources include on‐road emissions, cattle operations, agriculture and construction. A ccording to ADEQ’s technical rep ort, these sources of PM 10 are distributed throughout the western portion of Pinal County, including areas to the east and south of the Governor’s recommended boundary. See Figures 3 ‐3 and 3‐4 of ADEQ’s technical report. EPA’s review o f meteorological data and topog raphy indicates emissions

from these areas are sometimes t ransported to the violating mon itors.  The CAA requires that nonattainment areas encompa ss nearby areas that contribute to air quality in the area where violations are measured. The statute does not set any “si gnificant contribution” threshold for excluding nearby a reas that contribute to violati ons, nor has any commenter provided one.  EPA does not believ e that the areas to the south east have a negligible contribution to violations. The predominance of southeast winds support boundaries that extend south and east of the violating monitors because PM 10 sources, including agricultural activities and unpa ved roads, are found in those d irections. EPA’s recommended boundaries encompass the types of sources that are believed to cause or

ontribute to the monitored violations and that are located eas t and south of the violating

onitors. Also c

m15 the main sources of PM 10 emissions are on‐road vehicle tr avel and agricultural activitie s, in

he western/ west central and no rthern parts of the county wher e the monitored violations t
have occurred.

The Farm Bureau contended that the ADEQ inventory data, which it characterized as identifying on‐road sources as the major contributor to PM 10 emissions in Pinal County, is

upported by the observation that violating monitors are locate d in the more densely opulated area s

p s in the western portion of the county.

Response (8): As noted in our TSD, the 2003 Source Apportionment Study 17 concluded

that the dominant PM 10 source in Pinal County was soil , with the exception of the Cow town monitor, which was significantly influenced by cattle feedlot emissions.  These findings were reinforced by inf ormation gathered in 2 009 during an EPA‐f unded RARE project. 18 ADEQ’s preliminary inventory and the NEI agree that main sources of primary PM 10 are

aved and unpaved roads (collect ively referred to as “on‐road” emissions), agriculture, and p
construction activities.

APS did not define the geographic extent of the “agricultural basin;” however, we note that agricultural operations are widely distributed in the western h alf of Pinal County and are

not limited to the area within the Governor’s recommended bound ary.  See Figure 3 for a

ap showing EPA’s final boun daries for the West Pinal PM 10 nonattainment area and the m generalized land uses found th erein and in the vicinity.

EPA’s final nonattainment area encompasses the area recommended by the State of Arizona, but extends farther to t he south and west. The eastern boundary now partially

coincides with the State’s reco mmended boundary (the north‐sout h line defined by the boundary between townships 8E and 9E) but extends farther to th e east to include the Florence area and several nearby townships in order to include significant sources of PM 10 emissions 19 , and, in the southern part of t he nonattainment area, to inclu de the Picacho

eak area where severe dust storms have caused impaired visibil ity leading to traffic ccidents and, P

a in some cases, fatalities.

Comment (9): A citizen argued that the area to the south of the Governor’s recommended boundary, which coincides roughl y with Interstate 8 (I‐8), shou ld not be included because it is predominantly farmland with almost no residential or indu strial areas, and, according to Arizona’s preliminary emission s inventory, tilling, harvesti ng, and agriculture constitute 4.9% of the inventory. The commenter also asserted that the sou thern portion of the Pinal County should not be included in the nonattainment area because the area has no roads, other than I‐10, that lead to an y major urban centers, and the monitors near I‐10 in the

17 Pinal County Air Quality Contro l District Sourc e Apportionment Study: July 29, 2005, page 43.

18 “Chemical Analysis for Source A ttribution of Fine and Coarse P articulate Matter in Pinal County, Arizona” Andrea L.Clements, Yuling Jia, Matthew P. Fraser, Pierre Herkes , Michael Sundblom, and Paul A. Solomon,

pr i

esentation to American Aerosol Researech Association (AARA) 2 8 th Annual Conference, M nneapolis, Minnesota, October 26 – 30, 2009.

19 See Figure 3 of this RTC and App endix B of Arizona’s technical report– ADEQ Maps of PM 10 Sources.16 southern portion of the county ( at Eloy and Pinal Air Park) are not in violation of the PM 10 NAAQS. The commenter suggested t hat EPA has assumed that southe rn Pinal County

should be included since it is t he same as the area surrounding the Pinal County Housing monitor, but noted the condition s at the latter are influenced by significant local sources,

uch as a dirt race track, count y fairgrounds, and concentrated vehicle traffic, that are not epresentative s

r of conditions in the southern portion of the cou nty.

Response (9): Based on our review of the comments and the data, including th e geographic distribution of sources of PM 10 and the building permit data provided by Pinal County that document the extent to which the national recession has slowed growth in Pinal County, we have adopted a more limited expansion of the S tate‐recommended southern boundary than we had proposed. EPA’s inclusion of some area south of Arizona’s recommended boundary is rooted in the CAA’s definition of nonat tainment area in 107(d)(A)(1) to include areas that are contributing to air qual ity at a nearby area that is violating. EPA has concluded tha t there are sources south of I‐8 that are contributing to the

levels of PM 10 measured at the violating monit ors. Our conclusion is based in part on the presence and proximity of source s in categories shown to contri bute to air quality in the violating area, as well as on meteorological data indicating tr ansport to those areas where violations are being measured. Fu rther, the history of dust sto rms and resulting traffic accidents in the Picacho Peak area, which lies to the southeast of the State’s recommended boundary, provides evidence that the disturbed land surface in this area is likely a larger contributor to downwind violations than might otherwise be sugg ested by the aggregate

emissions and land use data. The CAA does not require a nearby area’s contribution to be “significant” to warrant inclusi on in the nonattainment area bo undaries. See CAA section 107(d)(1)(A)(i). We also note th at recent revisions to emission s factors 20 could result in

reductions to the amount of emis sions attributed to on‐road sou rces. If this is the case, the relative percentage contribution of other source categories, in cluding tilling, harvesting and agriculture will increase.

O

ff

­ Highway Veh icles

Comment (10): The Arizona Game and Fish Department argued that because ADEQ ’s TSD states that off‐highway vehicle emissions are relatively low an d there were no grid cells

ver the 20 ton per year threshold, the nonattainment area boun dary should not include ndeveloped lan o

u ds where this type of recreation occurs.

Response (10): Upon consideration of public comment and further review of th e geographic distribution of source of emissions, EPA has revised our proposed nonattainment area boundary. We have established a final nonatt ainment area that we believe encompasses the areas in which PM 10 violations are being mo nitored, as well as the

oads, Measurement Policy Group, Office of 20 Emission Factor Determination f or AP‐42, Section 13.2.1 Paved R Air Quality Planning and Stand ards, U.S EPA (January 2011) http://www.epa.gov/ttn/chief/ap42/ch13/bgdocs/b13s0201.pdf17 areas that contribute to the monitored violations, consistent w ith the definition of

nonattainment areas in CAA sect ion 107(d)(1)(A). While this mig ht result in the inclusion of some lands where off‐highway vehicle recreation occurs, it d oes not dictate controls or the regulation of emissions generated by such activities. Arizo na will be required to develop a plan that results in t he attainment of the air qualit y standard for PM 10 , it will be

the State’s role to determine the relative contribution of vari ous sources and to consider and decide upon options for cont rol.   The State’s attainment p lan will be subject to public

eview and comment, both at the state level and again when EPA evaluates the plan for pproval or disapproval as a revi sion to the Arizona state impl ementation plan (SIP). r

a

W ilderness Areas

Comment (11): Four commenters objected to the inclusion of the Table Top an d Superstition Wilderness areas wi thin the nonattainment area, no ting that such areas are generally closed to mechanized eq uipment and do not include sou rces that could be contributing to exceedances at t he violating monitors. The Ariz ona Game and Fish Department and ADEQ also contend ed that EPA had not justified its decision to include the

wilderness areas and the Tonto National Forest in the nonattain ment area. The Arizona

ame and Fish Department request ed that EPA remove these areas and other largely ndeveloped, ru G

u ral areas from the nonattainment boundary.

Response (11): EPA agrees that, because the wil derness areas and the Tonto N ational Forest are generally closed to m echanized equipment and lack emissions sources, the areas

do not contribute to violations at monitors elsewhere in Pinal County. As a result, we have

inalized boundaries that do not include either of the subject wilderness areas or any

ortion of the Tonto National Forest and that minimize the incl usion of undeveloped land. f

p

P opulation Den sity and Degree of Urbanization

Comment (12): Several commenters noted that the area south of Arizona’s rec ommended boundary is sparsely populated. ADEQ stated that the level of urbanization in the Eloy area differs from that in the areas surrounding the violating monito rs. ADEQ further argues that ts position is supported by th e 2007 satellite imagery that sh ows most of Eloy is sparsely i populated and that the “urbanize d” area of the city consists of approximately 1,130 acres.

Both the Arizona Farm Bureau Fed eration and the Pinal County Farm Bureau (collectively referred to as the Farm Bureau) challenged EPA’s proposed redes ignation to

nonattainment the area surroundi ng Eloy and running south to Pi ma County.  The Farm Bureau stated that that the popu lation densities in this area a re among the lowest in the county, and reflect far less human activity than other more pop ulated portions in western Pinal County.  The Farm Bureau a lso asserted that reduced econo mic activity in this area is ndicated by the monitors locate d in these areas that have reco rded attainment with

AAQS. i

N18 A citizen stated that the southern portion of the county has th e lowest population density and degree of urbanization of an y of the areas included in EPA’s proposed nonattainment area. In support of this assertio n, the commenter contrasted El oy’s density of 225 persons per square mile with the next highest settlement density of 929 persons per square mile (based on information in ADEQ’s TSD). The commenter contended t hat including the

outhern portion of the county i n the nonattainment area would serve no practical or ublic policy pu s

p rpose given the small population and clean data

.

Response (12): As noted in our TSD, population density can give an indication of whether it is likely that an area is cau sing or contributing to violati ons of the 24‐hour PM 10 standard, particularly in situations where activities correlated with population contribute to overall

missions.  In this case, popula tion density was among the fact ors considered because on‐ e road emissions are a significant contributor to PM 10 emissions in Pinal County.

Because on‐road emissions are distributed throughout the western half of Pinal County 21

, and because other sources in the County, including agriculture and cattle operations, which are not typically correlated with high population density, are responsible for PM 10

missions, it would be inappropriate to rely on population dens ity alone to determine e whether an area should be includ ed within the nonattainment bou ndary.

Upon further consideration, EPA has determined that certain are as that had been included in the proposed nonattainment ar ea, including some areas in the southern portion of Pinal County, are unlikely to be causing or contributing to violation s of the PM 10 NAAQS.  As a result, EPA is modifying its pro posed boundary to exclude those areas.  See Figure 2, which compares EPA’s proposed and final nonattainment area boundaries. Our decision is based

on the low level or absence of t he types of activities that con tribute to elevated PM 10 levels in Pinal County.  However, because of the presence of emissions generating activities in the

loy area and meteorological dat a that provide evidence of tran sport from the south, we

ave not exclude E

h d this area.

Comment (13): ADEQ argued that population and population density in Florenc e and Eloy is overstated because the numbers include the prison population

. 22 According to population data from 2008, when the prison population is exclud ed, the population density in Eloy drops from 146.9 to 102.6, and in Florence from 481.9 to 71.9. They argued that incarcerated prisoners do not engage in activities that contrib ute to elevated

concentrations of PM 10 . ADEQ asked EPA to reconsider the population densities and projections included in its initial boundary recommendation. ADEQ noted that, when the population densities are adjuste d to exclude prisoners, a compa rison of the revised population density to those in m ore urbanized areas of Pinal Co unty with violating onitors demonstrates that population‐driven activity levels in the areas of Florence and loy are less intense and have not resulted in violations of th e PM 10 NAAQS. m
E

21 See Figure 3‐4 of ADEQ’s technic al report, also reproduced in EPA’s TSD as Figure 9.

22 In 2008, 4,868 people were incar cerated in Eloy, and 17,186 pe ople were incarcerated in Florence.19 Response (13): EPA agrees that inclusion of pri soners in the calculation of p opulation density might skew the results o f efforts to draw nonattainment boundaries based solely on population density.  However, in this particular case, popul ation density was only one of many factors considered.  Because some sources of PM 10 in Pinal County (e.g., on‐road emissions) may be correlated to a degree with population densit y, a high population density in a locale could weigh in favor of its inclusion in th e nonattainment area.    On the other hand the emissions inventories and source apportionment s tudies of Pinal County also show that other contributing sources are typically correla ted with lower population density (agricultural operations, cattle operations). Therefore , while population density can be considered in determining the appropriate boundary, low population density alone

hould not in this case be a dec iding factor in determining whether to exclude an area from s the nonattainment area.

As noted above (response to comment 12), EPA has revised the bo undary to exclude certain areas that, based on our evaluation of comments and rev iew of satellite imagery, are not likely to be contributing to the violations measured in Pinal County.  However, because both Florence and Eloy a re located in areas that include sources of PM 10 that are

ontributing to elevated emission s levels at violating monitors , we have included them in

he final nonattainment area. c

t

T raffic and Com muting Patterns

Comment (14): Several commenters stated their belief that including the east ern and southern portions of the county in the nonattainment area is no t justified based on the traffic patterns and relatively l ow concentration of roads in t his area. Commenters stated that the largest category of PM 10 emissions in Pinal County is o n‐road sources, and asserted

that current traffic a nd commuter–related emissions are centered in the western portions of the county, in the more popul ated regions of Casa Grande and Maricopa.  Another

commenter noted that the number o f commuters traveling between Pima and Pinal counties is significantly less than the number traveling betwee n Maricopa and Pinal counties, and further contended that the area south of the Gove rnor’s recommended nonattainment area is generally n ot affected by commuting betwe en Pima and Pinal

counties.  One commenter stated that the area south of I‐8 does not have any roads that ead to major urban centers, except for I‐10, and the commenter contended that proximity l

to I‐10 does not cause violation s at the Pinal Air Park or Eloy monitors.

ADEQ cited statistics that indic ate the number of commuters tra veling between Pima and Pinal counties is significantly less than the number traveling between Maricopa and Pinal counties, as support for excludi ng the southern portion of Pina l County from the nonattainment area boundary.  ADE Q argued that the area south o f Arizona’s recommended boundary is sparsely populated, generally unaffecte d by commuting between Pinal and Pima counties, and is not likely to become a major employment center.

DEQ concluded that the original southern boundary in Arizona’s recommendation is

ustifiable under these factors. A j20 APS observed that commuting pattern data along the I‐10 corrido r in the Case Grande area show that the majority of commute r traffic is to the north towa rd the Phoenix metropolitan

area rather than south toward Tu cson. It contended that this lends support to the

conclusion that the main sources of PM 10 emissions are on‐road vehicle travel and

gricultural activities in the western/west central and northern parts of the county where a the monitored violations have occurred.

The Farm Bureau pointed to EPA’s data, arguing that they show t he majority of commuters

travel north to the Phoenix Metr opolitan area and that far fewe r commuters travel through the southern part of the county for employment purposes. The Fa rm Bureau contends this supports its argument against including the southern portion of the County in the nonattainment area. In addition, the Farm Bureau claimed that t he data support Arizona’s recommended boundaries, since they show traffic and commuting–r elated emissions and the violating monitors are conce ntrated in the more populated r egions of Casa Grande and Maricopa in the western portions of the County. The Farm Bureau contrasted this with the ess‐ traveled southern portion o f Pinal County, which contains the I‐10 corridor and where he monitors (El l

t oy and Pinal Air Park) located along that corri dor do not show violations.

Response (14): Although EPA and ADEQ inventor ies differed with respect to th e quantity of emissions generated by on‐road sources, there is agreement t hat this constitutes the largest category of PM 10 emissions in Pinal County. EPA TS D Figure 8 and ADEQ technical report Figure 3‐5 illustrate the distribution of commuter traff ic and emissions generated by traffic on paved roads. Taken tog ether with the overall distrib ution of on‐road emissions shown in ADEQ’s technical report (Figure 3‐4), it is evident that on‐road traffic (including aved and unpaved roads) is a significant source of emissions i n the western half of Pinal p County, including areas to the south and east of the Governor’s recommended boundary.

EPA believes that the distributi on of emissions from on‐road tr affic requires an expansion of Arizona’s recommended boundary; however, upon further review , we have concluded that the available data support a modification of our proposed boundary. The final

onattainment boundary therefore removes some of the eastern an d southern townships n that had been included in the proposed nonattainment area.

We were persuaded to revise our proposed boundary by our review of satellite imagery, maps of source locations, and ADEQ’s maps illustrating emissions estimates by township, which together illuminate land use and emissions. In certain ar eas (such as Florence, Eloy, Picacho Peak, and lands to the s outh of Interstate 8), the final boundary extends beyond the State’s recommended boundary. This was done to include areas th at, based on the location

of sources of PM 10 emissions, meteorological data that indicate winds from the so utheast ransport emissions to violating monitors, and topographic info rmation showing a lack of eographic barriers, are contributing to air quality at violati ng monitors. t

g21 n is justifiab le under these factors.

Response (15): In weighing growth rates and pa tterns, EPA considered informa tion presented in ADEQ’s technical report, including projected growth in population density and employment density.  Figures 3‐14 and 3‐17 of ADEQ’s technical report illustrate the southward and eastward expansion of relatively high population and employment densities that are expected to o ccur in the future. While this information provides additional justification for EPA’ s decision to exclude the east ern half of Pinal County from G rowth Rates and Patterns

Comment (15) :  Several commenters argued that growth forecasts made prior t o the economic downturn are no longer reliable given current economic conditions, and pointed to the uncertainty of future growth. Others noted that actual g rowth in the area south of the Governor’s recommended boundary has been modest, and that it is unlikely to become a major employment center.  These commenters questioned EPA’s ana lysis that future

mployment and population growth in Pinal County justifies incl uding the southern e portion of the county in t he nonattainment area.

PCAQ stated that foreseeable grow th patterns do not justify an expanded PM 10 nonattainment area. The Farm Bureau disagreed with EPA’s analys is that future employment and population growth in Pinal County justifies incl uding the southern portion of Pinal County, and the y asserted that a severe econom ic downturn occurred after the growth projections were developed. A citizen characterized the growth projections for the southern portion of the coun ty as grossly inadequate, due t o the recession, which she argued has hit Pinal County hard er than the nation as a whole. The commenter believes hat the population growth in th e southern portion of the count y will be significantly lower t than that relied upon by EPA.

ADEQ argued that population esti mates from the ADOT anticipated explosive growth in Pinal County starting shortly after 2000 and continuing through 2030, while in fact actual population growth in Pinal Count y has slowed considerably durin g the current economic downturn.  ADEQ also stated that the CAAG Employment Center Adj ustment Strategy (March 31, 2010) identifies Mari copa, Casa Grande, Coolidge, Fl orence, Queen Creek and Apache Junction, but not Eloy, as the principal employment cent ers in the County.  It concluded that the employment de nsity projections ADEQ included in its “strawman” boundary recommendation represented an optimistic view of the f uture developed at the height of the housing bubble that are now in serious doubt. ADE Q cited the uncertainty of growth forecasts in the midst of an economic recession and reco mmended collaboration

with stakeholders and EPA to add ress growth‐related emissions on an as‐needed basis, noting that the regulatory timef rame allows the State several opportunities to address any

additional control measures that may be necessary to reach atta inment. ADEQ urged EPA

to reconsider the southern bound ary of the proposed nonattainme nt area. It noted that the area south of Arizona’s recommended boundary is sparsely popula ted, generally unaffected by commuting between Pinal and P ima counties, and is not likely to become a major

mployment center.  ADEQ conclude d that the original southern b oundary in Arizona’s

ecommendatio e

r22 t he nonattainment area (while exp anding the area to the south a nd east of the Governor’s

g so. recommended boundary), it is not the sole, or even the most imp ortant reason for doin

We included the southern portion of Pinal County in the propose d nonattainment area based on a determination that the areas in the southern portion on Pinal County contribute

to the violations monitored fart her north.  Our determination i n this regard stemmed from our consideration of the nine pertinent factors, which are disc ussed in detail in the TSD and he proposed rule itself. In short, we determined that the southern portion contributed to t nonattainment, especially conside ring source mix and meteorolog y.

In our final action, in due consideration of the comments submi tted on our proposal, we are reducing the nonattainment area (relative to what we proposed on October 1, 2010) and we are not including the souther n‐most portion of Pinal County, the Table Top Wilderness area, and certain largely undist urbed desert areas that lie eas t of Township 8 East. The

Pinal Air Park monitor therefore is not included in the final b oundary.  We have determined, however to include t he Eloy monitor, because we con tinue to believe that the sources in the Eloy area contri bute to violations of the PM 10 NAAQS farther north, although we recognize that sources in and around Eloy do not contribute to every violation. We are persuaded to shrink the boundary in part based on the building permit data provided by Pinal County that documents the extent to which the national re cession has slowed growth generally in Pinal County, but in the I‐8 and I‐10 corridors in particular. We agree that the recession and overabundance in homes already in foreclosure wil l likely delay significant

rowth in the corridors beyond th e five‐year horizon for reachi ng attainment of the g standard. Also see our responses to Comment 6, 8, and 9, above.

We were persuaded to revise our proposed boundary by our review of satellite imagery, maps of source locations, and ADEQ’s maps illustrating emissions estimates by township, which together illuminate land use and emissions. In certain ar eas (such as Florence, Eloy, Picacho Peak, and lands to the s outh of Interstate 8), the final boundary extends beyond the State’s recommended boundary. This was done to include areas th at, based on the location

of sources of PM 10 emissions, meteorological data that indicate winds from the so utheast ransport emissions to violating monitors, and topographic info rmation showing a lack of eographic barri t

g ers, are contributing to air quality at violati ng monitors.

Comment (16): ADEQ disagreed with what it char acterized as EPA’s contention that growth‐related activity in the I‐10 corridor could lead to viol ations at the Eloy monitor. It argued that emissions from construction generally decrease foll owing the first phase of a project, and that the Pinal Coun ty Air Quality Control District enforces a suite of fugitive dust rules requiring control mea sures and technology at constru ction sites. It contended that these activities, while asso ciated with increased growth, can and would be controlled by existing rules implemented in areas outside of Arizona’s rec ommended boundary.

DEQ also asserted that general conformity in and around the no nattainment area will urther mitigate emissions from federally‐funded construction p rojects. A

f23 Response (17): EPA agrees that monitored concen trations at Eloy are not in th emselves a sufficient reason for including El oy and locations to the south east in the nonattainment area.  However, EPA included the southeast portion because of t he contribution of

southeast emissions to violations at the Casa Grande and Pinal County Housing monitors. EPA does not agree with the comm enters' implicit assumption tha t the southeast portion Response (16): EPA did not in its TSD, nor do we now contend that growth‐rel ated activity in the I‐10 corridor may lead to violations at the Elo y monitor. Rather, we took into consideration projected growth in the I‐10 corridor as one fact or weighing in support of

inclusion of the I‐10 corridor as contributing to violations at those monitors farther north that currently experience violations, EPA believes that emissio ns from sources in the Eloy

rea are currently contributing to air quality at violating mon itors. As a result, this area a must be included in the nonattainment area.

Pinal County AQCD has establishe d rules to reduce dust emission s at construction sites. The more restrictive rules apply only within existing nonattain ment areas and do not apply in or around Eloy. General conformity does not apply outside of nonattainment or aintenance areas and thus would not mitigate emissions from fe derally‐funded onstruction projects in the Eloy vicinity if it is not include d within the nonattainment area. m

c

M eteorology an d Transport

Comment (17): Both ADEQ (p.4) and PCAQ (p.2) commented that Eloy should not be included in the nonattainment area, since it does not have monitored violations.  ADEQ criticized EPA's use of wind roses to establish a predominantly southeastern wind direction, and added that "If win ds from the southeast were con tributing to exceedances at he violating monitors, the Eloy monitor would be violating as well," since Eloy is between t the violating monitors and the p resumed contributing areas to t he southeast.

ADEQ concluded that EPA’s assert ion that prevailing winds from the southeast and long‐ range transport are contributing to exceedances at the violatin g monitors is unfounded. ADEQ argued that the Eloy monitor is south, southeast of these violating monitors and does not show any expected exceedan ces based on the 2006‐2008, 2007‐ 2009, and 2010 onitoring data. If winds from the southeast were contributing to exceedances at the m violating monitors, ADEQ asserted that the Eloy monitor would b e violating as well.

The Farm Bureau expressed concern that EPA has chosen to includ e areas that may

contribute to PM 10 emissions without scientific just ification for its assumption.

A citizen contended that EPA has assumed that the PM 10 emissions from sources in southern Pinal County are transp orted by “predominantly southea sterly winds” to the violating monitors in the central portion of the county, and th at EPA relied upon the county line as a “default” boundary. Th e commenter argued that EPA’s u se of this “default” boundary line  is wrong, based o n the fact that the Eloy and Pi nal Air Park monitors have

ever shown a violation in the a rea from which the emissions ar e supposedly being ransported. n

t24 rized by a combination o f changes in wind direction and spikes in PM 10 must be the sole or main cause o f violations in order for it to be included in the

nonattainment area.  Emissions fr om the southeast may not be su fficient to cause a violation at Eloy , yet could st ill contribute to violations farther northwest.  EPA believes there is such a southeast area contribution, and it contributes sufficiently to violations to

rovide a basis for including  Eloy and a portion of the southe ast  in the nonattainment

rea. p

a

Comment (18): PCAQ commented (p.3) that meteor ological data is sparse in the 25‐mile

orth‐south expanse of the portion of EPA's proposed nonattainm ent area, and is not

ufficient to war n

s rant including that portion.

Response (18): EPA agrees that additional meteorological data in the area is desirable. However, a decision on the nonattainment area boundary must be made with the data currently available.  As discusse d in EPA's proposal and TSD, E PA believes that there is sufficient meteorological data fr om the AZMET (Arizona Meteorol ogical Network) stations within and around the proposed area to show that flow from the southeast toward the violating monitors occurs often. EPA believes that this applie s even during the exceedance days discounted by ADEQ and PCAQ (see response to comment 19). The available meteorological data provide evid ence that emissions sources in the southeast contribute to

AAQS violations and therefore p rovide justification for includ ing  the southeast  in the

onattainment a N

n rea.

Comment (19): Both ADEQ (pp.4‐6) and PCAQ (p .3 and attached memo) examined HYSPLIT back‐trajectories for several high‐wind exceedance days , along with hourly

concentrations and wind data.  F rom the abrupt changes in wind direction and increases in

ind speed that often coincide d with large increases in PM 10 concentrations, they w concluded that the PM 10 is due to near‐field impacts rather than to long‐range transpo rt.

ADEQ noted that the statistically dominant wind direction for h igh wind events is typically from the west and southwest, and conducted a review to determin e the extent to which

PM 10 exceedances occurred when winds were from the southeast. The e valuation utilized

PM 10 monitoring data collected at the Pinal County Housing, Casa Gr ande Downtown and Stanfield monitors during 2007 through the 3 rd quarter of 2010. The data set was first screened to identify exceedance days where winds and stagnation were noted as the preliminary contributor. The NOAA HYSPLIT 23 model was run for each identified day and the result was reviewed to provide a general wind direction. This process identified 56 wind exceedance days. In order t o evaluate potential contributi on areas from the SE or SSE, a second screen was applied to remove any day on which the wind was not from those

directions. The result identified five wind event days: August 16, 2007, August 29, 2007, August 8, 2008, October 27, 20 08, and September 3, 2009. The HY SPIT data were

characte

23 HYSPLIT is the Hybrid Single Particle Lagrangian Integrated Tr ajectory Model, Air Resources Laboratory of the National Oceanic and Atmospheric Administrati on (NOAA), web site http://ready.arl.noaa.gov/HYSPLI T.php.  Using weather data, it can show the paths (trajectories) along which air parcels arrived at a given time and place.25 concentrations. ADEQ contended that this demonstrates near‐fiel d impacts, rather than long‐range transport, as the maj or contributor. They also concl uded that the analysis showed that wind‐transport from the southeast is not a dominant contributing factor for

PM 10 exceedances at the monitors in other portions of the county an d noted that each of the referenced days has been flagged as an exceptional event. The same type of analysis was completed for stagnation day s. During the period 2007 throu gh the 3 rd quarter of 2010, 13 stagnation days were ide ntified. When the data set was screened for those days

when the wind direction was from the SE or SSE, only one date w as identified, November 4, 2009. ADEQ asserted that the comparison of the back trajectory and the hourly particulate

evels indicates that the PM 10 contribution to the ambient monitors was from the

mmediate vicin l

i ity and not from long‐range transport from the s outheast.

Response (19): EPA agrees that the analyses performed by ADEQ and PCAQ provid e useful information for evaluating the PM 10 exceedances.  However, as discussed above, in setting

nonattainment area boundaries on e has to distinguish between th e sole or main cause of an exceedance, and a contribution t o the exceedance.  Even if the commenters are correct that "wind‐transport from the southea st is not a dominant contributi ng factor" (ADEQ p.4) and that the data "suggest a typical monsoon storm where local weat her contributed to local impacts" (PCAQ p.3), transported emissions from the southeast n onattainment area portion nevertheless contribute sufficiently to exceedances at violating monitors to provide a basis for including the southe st portion in the nonattainment area. As discussed in the SD for EPA's proposal, and also below, EPA believes that the m eteorological data provides T

evidence for such a contribution.

Both ADEQ and PCAQ examined exceedance days for which HYSPLIT b ack‐trajectories approached monitors from the sou theast.  PCAQ mentioned that there are relatively few such days, only 5 (or 9%) out of 56 total high wind exceedance days in 2007‐2009: August 16, 2007, August 29, 2007, August 7, 2008, October 27, 2008, an d September 3, 2009 (p.3). ADEQ examined the same days, exc ept August 8 was used instead of August 7, 2008.  Even if there are relatively few days with transport from the southe ast, EPA must consider them in setting the nonattainment are a boundary.  In any case, there may be additional days with southeast transport that are not found by the HYSPLIT screening procedure used by the commenters.  They looked for days with the trajectory's ending hour oriented from the southeast, but this does not con sider other hours during the da y that may have flow from the southeast.  In addition, whil e HYSPLIT trajectories are a v ery useful tool, it is not clear they have adequate spatial resol ution to draw conclusions about source contributions or specific nonattainment area boun daries on the scale of 10‐20 mi les, which is approximately  how far the EPA no nattainment area extends beyon d the ADEQ recommendation.  Some of the traje ctories are hundreds of miles long.  The underlying

GDAS 24 meteorological data used by ADE Q and PCAQ with HYSPLIT has a r esolution of one degree of latitude or longitude, or roughly 60 miles.  Thus EPA does not believe that the

24 GDAS is the Global Data Assimila tion System, a weather model i ncorporating data from weather

stations around the world. Web s ite http://ready.arl.noaa.gov/g das1.php26 c ommenters' analyses can be definitive about transport from the southeast portion of the proposed nonattainment area.

Even for the days selected by th e commenters, the meteorologica l data suggest a

contribution from the southeast. AZMET data show wind from the southeast for at least a quarter of the day (6 or more ho urs) on August 16, 2007, August 29, 2007, and August 7, 2008.  This is true for the Queen Creek AZMET station, which is near the Combs School

PM 10 monitor; the Coolidge AZMET sta tion, north of the Pinal County Housing monitor; and for the Marana AZMET station, southeast of the southeast corner of EPA's proposed

nonattainment area.  While for s ome of the hours the southeaste rly wind direction does not

coincide with the PM 10 concentration spike noted by PCAQ, still there are enough hours with southeast winds to suggest s ome contribution from the sout heast to the 24‐hour PM 10 concentrations.  For October 27, 2008, as was stated by PCAQ, t here were sustained winds from the southeast during much o f the day at the Queen Creek an d Marana AZMET stations, consistent with transport from the southeast portion of the pro posed nonattainment area. Winds at the Coolidge A ZMET station were from the east‐northeast; this is consistent with transport from the eastern porti on of the proposed nonattainmen t area (the inclusion of which has also been opposed by ADEQ).  Thus, for at least four of the five days examined by ADEQ and PCAQ, EPA believes that the southeastern and eastern p ortions of the proposed nonattainment area do contribute to NAAQS exceedances. These re lationships are illustrated in the wind roses in Figure 4. 25 These wind roses were created by EPA using

wind data from the Cowtown and A ZMET meteorological stations on days when nearest

PM 10 monitor has a NAAQS exceedan ce during 2006‐2008.  Although 200 9 meteorological

ata were not available at the time of this analysis, the wind roses generally show that on xceedance days, winds are fre quently from the southeast. d

e

25 Wind roses show the percentage of the time that wind blows from the various compass directions in various wind speed ranges.27 The commenters' analyses do provide some evidence that local so urces are more important for monitored exceedances than long range ones.  The main contributors to PM 10 exceedances may indeed be relati vely near the monitors (though as already discussed, other contributions to NAAQS exceedances should be included in the nonattainment area). Figure 4. Pinal County Wind Roses28 oundaries

Comment (21): One commenter stated that juri sdictional boundaries alone should not

decide whether an area is includ ed within the boundary of a nonattainment area. The

commenter believes that EPA assumed that the PM 10 emissions from sources in southern Pinal County are transported by “predominantly southeasterly wi nds” to the violating monitors in the central portion of the county, and relied upon the county line as a “default” boundary. The commenter found EPA ’s assumption and use of the “ default” to be However, a fundamental problem w ith the analyses is that the te rms "local" and "long range transport" are subjective unless specifically defined.  S uch qualitative terms are useful for thinking about the PM 10 exceedances, but they do no t provide a nonattainment area boundary: any particular di stance of the nonattainment are a boundary from the monitor could be considered by s omeone to be too far away to be considered “local.” In any event, EPA does not believe that emissions traveling 10‐20 mile s can be dismissed as “long range transport.”  The southeast corner of EPA’s final nonattai nment area boundary is about 22 miles from the violating Pinal County Housing monitor.  Dust from locations in the southeast portion of the nonattainment area could be transporte d to that monitor by a

ingle hour of 20 mph wind, or b y multiple hours of lower wind speeds, such as were s observed on the days described above.

EPA believes that areas southeas t of the violating monitors con tribute to NAAQS violations and can be considered “nearby ar eas” and so should be included in the nonattainment area. However, as noted above, EPA has reduced the size of its proposed nonattainment area.  In this final action, EPA has established the nonattainment area b oundary to include a contiguous area in the east and southeast from which the wind t ransports emissions from roads, construction, disturbed l and, and agricultural activitie s toward monitors violating

the PM 10 NAAQS.  The degree of emission c ontrol needed for such sources would be

etermined by a more detailed an alysis of particular days and s ources as part of the State's orthcoming atta d

f inment demonstration.

Comment (20): PCAQ identified October 27, 2008 as a day with wind‐driven PM 10 exceedances that had sustained w ind from the southeast (p.3 and attached memo p.2), but commented that this single day of apparent transport from the s outheast is not a robust basis for including this portion of the County in the nonattain ment area.  The commenter

oncluded that available data do es not support characterizing southern Pinal County as a

ource of PM 10 tr c

s ansport that consistently affe cts the violating monitors to t he north.

Response (20): EPA does not agree that this is the only day for which there is significant wind from the southeast (see response 19 above).  As described in our TSD and above, there is meteorological evidence that emissions from the southe ast are transported to the exceeding monitor.   For the reaso ns set forth in the TSD and e lsewhere in these responses,

PA believes that the southeast contributes to violations and s o should be included in the

onattainment area. E

n

J urisdictional B29 lations of the secondary PM 10 NAAQS could be occurring.

Response (22): In determining the final boundary for the West Pinal PM 10 nonattainment area, EPA took into account the history of dust storms and resu lting traffic accidents in the erroneous, based on the fact tha t the Eloy and Pinal Air Park m onitors have never sho violation in the area from which the emissions are supposedly b eing transported. The commenter acknowledged that EPA has indicated that it would be inequitable to include less than an entire city within a nonattainment area, b ut pointed to the relatively more extensive size of city limits in Arizona (compared to else where in the country), and

sserted that  city  jurisdictio nal boundaries alone should not be determinative of the oundary for the wed a

a b non attainment area.

Response (21): Based on the available data, EP A continues to believe there is meteorological evidence that emissions from the southeast are t ransported to the violating monitors, and that areas to the southeast of the State’s recomm ended boundary contribute

to violations and so should be i ncluded in the nonattainment ar ea. See EPA’s responses to
comments 18 – 20. However, as not ed above, EPA has reduced the size of its proposed

nonattainment area to exclude wilderness areas and national for est lands and certain less‐ developed areas with relatively low levels of emissions.  See F igure 3 of this RTC, which illustrates the final boundary along with the distribution of s ources of emissions, and Appendix B of Arizona’s technical report, which includes severa l maps illustrating the

distribution of PM 10 sources in Pinal County. The final nonattainment area does not extend

s far to the east and south as the proposed boundary, and no l onger coincides with the a southern county boundary.

We were persuaded to revise our proposed boundary by our review of satellite imagery, maps of source locations, and ADEQ’s maps illustrating emissions estimates by township, which together illuminate land use and emissions. In certain ar eas (such as Florence, Eloy. Picacho Peak, and lands to the s outh of Interstate 8), the final boundary extends beyond the State’s recommended boundary. This was done to include areas th at, based on the location

of sources of PM 10 emissions, meteorological data that indicate winds from the so utheast ransport emissions to violating monitors, and topographic info rmation showing a lack of t geographic barriers, are contributing to air quality at violati ng monitors.

Jurisdiction is one of many facto rs EPA considers in its creati on of a nonattainment area boundary.  The weight given to a ny particular factor depends on the circumstances that

xist in the area under consideration.  In this particular case , no portion of the proposed oundary was drawn solely to ens ure that an entire city would be included. e b

S econdary Stan dard

Comment (22): The Sierra Club stated its position that a conservative approa ch to the nonattainment boundaries is warranted in light of the exceedanc es of the public health‐ based primary PM 10 NAAQS, and also in light of anecdotal evidence and news report s

oncerning instances of unsafe driving conditions along I‐10 ca used by blowing dust, uring which vio c d30 P

p icacho Peak area. 26 We note that the secondary standard for PM 10 is the same as the

rimary standard.

E conomic Impac t

Comment (23): The Arizona Game and Fish Department, which described its prima ry interest as maintaining lawful, reasonable public access for th e use of motor vehicles in Pinal County for outdoor‐related recreation, expressed concern over the inclusion of portions of four game management units within the nonattainment area.  The commenter anticipated that motor vehicle t ravel on those lands would be r estricted in an effort to meet the NAAQS, which could result in a loss of hunting and fishing opportunities. Because funding to manage and restore wi ldlife habitat and populations comes from the sale of hunting licenses and big game ta gs, a subsequent loss of fundin g to the AGFD could occur.

he commenter also noted that hunters and anglers contribute si gnificantly to the local

conomy. T

e

Response (23): To respond to this comment, EP A reviewed the maps of game management units that are available from the Arizona Game and F ish Department’s website and identified seven game management units that overlap portions of EPA’s proposed nonattainment area: 24B, 25M, 37A, 37B, 39, 40A, and 4 7M. The final

nonattainment area boundaries do not overlap with two of the se ven game management units that had been included in p art within the proposed nonatt ainment area boundaries: 24B and 47M. For two other units (37B and 40A), the overlap of the final nonattainment area boundaries and the game management units has been reduced to a small fraction of the overall size of the management units. For unit 37A, the ove rlap has been reduced significantly and now hews more closely to the agricultural are as in and around Eloy. For unit 39, the final boundaries ov erlap with the unit boundaries to the extent the unit extends nto Pinal County, but the vast majority of unit 39 lies within Maricopa County and would i not be affected by the redesigna tion of a portion of Pinal County for the PM 10 standard.

The greatest overlap between the final nonattainment area bound aries and the boundaries of the various game management units would occur with unit 25M. However, much of this unit has been developed by residential, commercial or agricultu ral uses and hunting opportunities there are quite limited. As to unit 25M, Arizona Game and Fish Department

states on its website: “For 25M o nly – the majority of the unit has either been converted to residential/agricultural uses or lies within the jurisdiction of the Gila River Indian Reservation. Discharge of firearms in the incorporated parts of the unit may be limited by local city ordinance. Hunters wi ll need to take great care to m ake sure they are not in city imits and more then 1⁄4 mi from residences. Hunting on the Gila Rivers Indian Reservation, f allowed, is governed by the Tribe.” l

i

26 See pages 12 and 13 of ADEQ’s Fe bruary 9, 2012 presentation ent itled, “Pinal County PM 10 and PM 2.5 Nonattainment Areas,” a vailable at http:// www.azdeq.gov/environ /air/plan/download/020912adeqpp.pdf.31 Thus, EPA acknowledges that the final boundaries would overlap portions of certain game management units but notes that the extent of overlap has been reduced significantly (relative to the nonattainment area boundaries, as proposed) an d that the unit most affected is also the unit (25M) where hunting opportunities are the most limited for reasons other than those related to air quality. Moreover, incl usion of portions of game management units within the nonattainment area boundaries does not prejudge the need for controls or regulation of em issions generated by motor vehi cle travel on those lands. As noted above, Arizona will be req uired to develop a plan that re sults in the attainment of the air quality standard for PM 10 , and the relative contribution of various sources and options

for control will be considered in that process.  That plan will be subject to public review

nd comment, both at the state level and again when EPA evaluat es the sufficiency of the

lan. a

p

S cientific Justifi cation

Comment (24): The Arizona Cotton Growers Association asserted that, without s cientific justification, EPA simp ly assumed that the PM 10 sources (agricultural operations, feedlots, dairies, CAFO’s, and road emission s) in the eastern and souther n areas of Pinal County are transported by predominantly sou theasterly winds to the violati ng monitors in the central portion of the county.  The Farm Bureau expressed concern that EPA has chosen to include

reas that may contribute to PM 10 emissions with no scientif ic justification for its ssumption. a

a

Response (24): Based on the available data, EPA continues to believe there is meteorological evidence that emissions from the southeast are t ransported to the exceeding monitors and that areas to the southeast of the State ’s recommended boundary contribute to violations. See EPA’s TSD and the responses to co mments 17 – 20, above. However, as noted above, based o n our review of comments, we ha ve reduced the size of the proposed nonattainment area. See responses to comments 9, 11, 12, 14, 15 and 21.

he final nonattainment area does not extend as far to the east and south as the proposed T boundary.32 exceptional events flags. The existing Phoenix PM 10 nona Apache Junction portion of weste rn Pinal County) is unaf 

### III. F INAL 

### A CTION

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 i nformation and considerations, and our review o f the submitted recommendations , EPA is redesignating

from “unclassifiable” to “nonatt ainment” an area generally cove ring the western half of Pinal County, Arizona, for the 1987 PM 10 NAAQS and therefore revising the boundaries of the existing “rest of state” unc lassifiable area. EPA’s decisio n to establish this new PM 10 nonattainment area, referred to a s “West Pinal,” is based on nu merous recorded violations

of the PM 10 standard at various monitoring sites within the county, and on the other grounds set forth in the proposal and in the TSD.

EPA’s final nonattainment area encompasses the area recommended by the State of Arizona, but extends farther to t he south, east, and west.  The eastern boundary now partially coincides with the State’s recommended boundary (the north‐south line defined by the boundary between township s 8E and 9E) but extends farthe r to the east to include

the Florence area and several ne arby townships and, in the sout hern part of the nonattainment area, to include the Picacho Peak area. Based on the comments received on the proposed rule, as well as further evaluation, EPA is modify ing its proposed boundary to exclude a portion of the Sonoran Desert National Monument (including the Table Top Wilderness Area), the Tonto National Forest and Superstition Wi lderness Area, the Ironwood Forest National Monument, and certain undeveloped land s. The revision to our proposed boundary is based on ou r review of satellite imagery, maps of source locations, and ADEQ’s maps illustrating emi ssions estimates by township, w hich together illuminate

land use and emissions. In certai n areas (such as Florence, Elo y, Picacho Peak, and lands to the south of Interstate 8), the final boundary extends beyond t he State’s recommended boundary. This was done to inclu de areas that, based on the loc ation of sources of PM 10 emissions, meteorological data t hat indicate winds from the sou theast transport emissions to violating monitors, and topog raphic information showing a la ck of geographic barriers, are contributing to air quality at violating monitors. The West Pinal PM 10 nonattainment area will be classified as “moderate” by operation of law.

EPA has determined that activit ies occurring on the main Tohono O’odham Nation (TON) reservation are not causing or contributing to violations occur ring in Pinal County and we are therefore finalizing our pro posal to exclude the main TON r eservation from the new nonattainment area. San Carlos Apache lands, which are located in the eastern quarter of the county, are excluded from the proposed nonattainment area along with the rest of the eastern half of the county. EPA is deferring its decision regar ding redesignation of the Ak‐

Chin and Gila River Indian Commu nity lands, as well as TON’s Fl orence Village and San Lucy Farms, pending consideration of issues unique to tribal la nds, completion of formal consultation with the tribal gov ernments, and (in the case of G RIC) consideration of ttainment area (including the

fected by this action.33 

### I V. L IS T OF 

### C OMMENT 

### L ETTERS 

### R ECEIVED

• uality Benjamin G rumbles, Director, Ari zona Department of Environmenta l Q

• ( October 28, 2010).

• Jim Thompson, City Manager, City of Casa Grande (October 28, 20 10). Tiffany Shedd, Esq. (October 28, 2010).

• ge District Ron McEachern, Gen eral Manager, Central Arizona Irrigation and Draina

• ( October 29, 2010).
Mike Norris, President, Pinal Co unty Farm Bureau (November 1, 2 010).

• ice Scott Davis, Director, Environmental Policy and Programs, Arizo na Public Serv

• Company (November 1, 2010). Donald P. Gabrielson, Director, Pinal County Air Quality (Novem ber 1, 2010).

•
, Sandy Bahr, Chapter Director, Si erra Club – Grand Canyon Chapte r (November 1

• 2 010). Kevin Rogers, President, Arizona Farm Bureau Federation (Novemb er 1, 2010).

• Rod Lucas, Regional M anager, Mes a, Arizona Game and Fish Depart ment (November 1, 2010 – transmitted to EPA via email on November 3, 2010).

• C. Lewis, Executive Vice President, Arizona Cotton Growers Asso ciation (October 27, 2010).