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December 2010 Addendum to EPA’s May 5, 2010 Technic al Support Document

Pinal County, Arizona Area Designation for the 2006 24-hour Fine Particle National Ambient Air Qua lity Standards

The table below identifies the portion of Pinal Cou nty in Arizona that EPA has designated as not attaining the 2006 24-hour fine particle (PM 2.5 ) national ambient air quality standard (NAAQS). A county (or part thereof) is designated as nonatta inment if it has an air quality monitor that is violating the standard or if the county or portion of the county is determined to be contributing to the violation of the standard in a nearby area.

Area Arizona Recommended

Nonattainment Area within Pinal County EPA’s Final Designated Nonattainment Area within Pinal County

Pinal T4S, R3E – R4E

T5S, R3E – R4E (excluding sections 12, 13, 24, and 25) T4S, R2E – R4E, except Indian Country; T5S, R2E – R4E, except Indian Country;
T6S, R2E – R4E; T7S, R2E, except sections 13 - 36; T7S, R3E, except-

• NW 1⁄4 , NW 1⁄4 of section 15, SW 1⁄4 , NW 1⁄4 of section 15, NW 1⁄4 , SW 1⁄4 of section 15, SW 1⁄4 , SW 1⁄4 of section 15;

• sections 16 – 21;

• NW 1⁄4 , NW 1⁄4 of section 22, SW 1⁄4 , NW 1⁄4 of section 22, NW 1⁄4 , SW 1⁄4 of section 22, SW 1⁄4 , SW 1⁄4 of section 22;

• NW 1⁄4 , NW 1⁄4 of section 27, SW 1⁄4 , NW 1⁄4 of section 27, NW 1⁄4 , SW 1⁄4 of section 27, SW 1⁄4 , SW 1⁄4 of section 27;

• sections 28-33; and

• NW 1⁄4 , NW 1⁄4 of section 34, SW 1⁄4 , NW 1⁄4 of section 34, NW 1⁄4 , SW 1⁄4 of section 34, SW 1⁄4 , SW 1⁄4 of section 34;
T7S, R4E

EPA has designated the remainder of state lands wit hin Pinal County, Cochise, Gila, Graham, La Paz, Maricopa, Pima, Yavapai, and Yuma counties, an d, except as noted below, Indian country located within those counties, as “unclassifiable/a ttainment.” EPA is deferring designation of the Gila River Indian Community reservation which is lo cated in Pinal and Maricopa counties, and Ak-Chin Indian Community reservation, which is loca ted in this portion of Pinal County. See Figure 1-A.2Figure 1-A: Areas Newly Designated for the 2006 24-Hour PM2.5NAAQS

U n i t e d S t a t e s

U n i t e d S t a t e s

M e x i c o

M e x i c oWest Central PinalPM2.5Nonattainment Area - FINALPima CountyMaricopa CountyYavapai CountyPinal CountyGila CountyYuma CountyCochise CountyLa Paz CountyGraham CountySanta Cruz County0 25 5012.5 MilesAIR1000054_9 28 October 2010Sources: EPA (2010), ESRI (2010),TANA (2006).Final EPA PM-2.5 NAADeferred Tribal LandsDesignated PM-2.5 NAAPreviously Deferred AreaDesignated "Unclassifiable/Attainment"Proposed EPA PM-25 NAA3

Background

In October of 2009, EPA notified the Governor of Ar izona and Tribal leaders of tribes with lands located in Pinal and Maricopa counties that a monit or in Pinal County (i.e., the “Cowtown” monitor) was violating the 2006 24-hour PM 2.5 standard based on the most recent (2006-2008) air quality monitoring data. Due to this newly mon itored violation, and due to the need for

additional time to collect data and evaluate the ar ea to determine an appropriate nonattainment area boundary for the area, EPA decided to defer th e area designation of Pinal County, Maricopa County (i.e., the other county comprising the Phoen ix-Mesa-Scottsdale CBSA), and the seven nearby counties (i.e., Cochise, Gila, Graham, La Pa z, Pima, Yavapai, and Yuma counties) surrounding the Phoenix-Mesa-Scottsdale CBSA, 1 for the 2006 24-hour PM 2.5 standard and potentially contributing to the violations of the N AAQS in Pinal County. 2 See Figure 1 of EPA’s May 5, 2010 Technical Support Document (TSD).

On May 10, 2010, EPA notified the Governor of Arizo na of its intent to designate a portion of Pinal County nonattainment for the 2006 24-hour PM 2.5 NAAQS thereby modifying the recommendation for an attainment designation for Pi nal previously made by Arizona. In its TSD, EPA explained that emission inventory data, combine d with speciation and source apportionment data, point to agricultural activities and cattle f eedlots, as well as other nearby sources of PM 2.5 , as primary sources contributing to PM 2.5 levels at the Cowtown monitor on days with

exceedances of the 24-hour PM 2.5 NAAQS. In addition, EPA assessed air quality and meteorological data, including data on monthly exce edances of the 24-hour PM 2.5 standards; wind direction and speed for hourly and daily PM 2.5 levels; correlation of PM 2.5 with PM 10 at the Cowtown monitoring site; and the diurnal pattern of PM 10 , wind speed, and temperature for

PM 2.5 exceedance days. Results of these assessments led EPA to conclude that agricultural lands and cattle feedlots, and activities associated with these operations, particularly those to the south and southwest of the monitor, contributed to PM 2.5 levels at the monitoring site. By contrast,

EPA concluded that the emissions sources in surroun ding counties and eastern Pinal County are not contributing to the violations of the 2006 24-h our PM 2.5 standard measured at the Cowtown monitor. Therefore, EPA proposed to designate the central-western portion of Pinal County, Arizona, as “nonattainment” for the 24-hour PM 2.5 NAAQS as shown in Figure 2 of EPA’s (TSD).

In a letter dated July 19, 2010, the Governor of Ar izona responded to EPA’s May 10, 2010 notification of its intention to modify the state’s initial designation recommendation. The Governor argued that a nonattainment designation wa s unwarranted, given the evidence that

exceedances of the PM 2.5 NAAQS are an artifact of the high concentrations o f PM 10 , and given the progress Arizona is making in reducing PM 10 concentrations. EPA notes that these arguments did not address the fact that there are m onitored violations of the 2006 24-hour PM 2.5 NAAQS in the area, nor negate EPA’s obligation unde r section 107(d) to designate as

1 As described in EPA’s final rule promulgating init ial PM 2.5 designations for the 2006 24-hour standard, in evaluating areas potentially contributing to a moni tored violation, EPA examined those counties locate d in the surrounding metropolitan statistical area (in this case, Pinal and Maricopa counties), and those nearb y counties one or two adjacent rings beyond. See “Air Quality Des ignations for the 2006 24-hour Fine Particle (PM 2.5 ) National Ambient Air Quality Standards,” 74 FR 58688, Novemb er 13, 2009, page 58694.

2 Unless otherwise specified, references to “countie s” or to “Arizona” include all lands within the geo graphic boundary and do not differentiate between lands und er state or tribal jurisdiction.4

nonattainment those areas that are violating the NA AQS, or contributing to nearby areas that are violating the NAAQS.

Anticipating that EPA would move forward with the n onattainment designation for the Pinal area, the Governor also offered a “counter-proposal ” to EPA’s recommended nonattainment area boundary, which is significantly smaller than the b oundary EPA originally proposed in its TSD. See Figure 2-A. In support of the Governor’s recom mended alternative boundary, the Arizona Department of Environmental Quality (ADEQ) submitte d a technical report entitled “Arizona Air Quality Designations, Technical Support Documen t, Boundary Recommendation for the Pinal County 24-hour Standard PM 2.5 Nonattainment Area (July 13, 2010),” herein refer red to as ADEQ’s “technical report.”5

Figure 2-A. Arizona’s Recommended PM2.5 Nonattainm ent Area Boundary6

EPA has reviewed the Governor’s July 19, 2010 lette r and ADEQ’s technical report, and as a result has made a revision to the southwestern port ion of the originally proposed nonattainment boundary. We have determined that the Table Top Wi lderness Area, which occupies most of the southwestern corner of our proposed nonattainment a rea, along with state lands to the south of the wilderness area, are not likely to be contribut ing to the exceedances measured at the

Cowtown monitor due to the absence of sources of em issions of PM 2.5 or PM 2.5 precursors in the wilderness area. As illustrated by Figure 3-A (page 12 below) very few sources of PM 2.5 emissions are present in this area and future devel opment will be limited by virtue of the restrictions that apply to wilderness areas. Given these considerations, we are revising our proposed boundary for the nonattainment area to exc lude the Table Top Wilderness Area and

state lands to the south of the final nonattainment area. See Figure 4-A on page 13 of this

Addendum.

A summary of the main points in ADEQ’s technical re port and EPA’s analysis of these issues

follows.

Emissions Data

ADEQ’s July 13, 2010 technical report considered th e Pinal County source apportionment study conducted by the Pinal County Air Quality Control D istrict (PCAQCD) in 2003 and provided two back trajectories to analyze emissions transpor t to the Cowtown monitor. ADEQ’s technical report states that the modeled days show winds from the south-southwest, likely carrying particulate matter from feedlots, agricultural fiel ds, and unpaved roads. 3 Based on their analysis

of PM 2.5 versus PM 10 concentrations as presented in the July 13, 2010 d ocument, ADEQ

concludes that the concentrations seen at Cowtown a re attributable to nearby feedlots and agricultural activities. 4 In support of a smaller designated nonattainment a rea, ADEQ states that

the other PM 2.5 monitors in Arizona (Casa Grande, Apache Junction, Douglas, and others shown in Figure 4 of EPA’s TSD) record considerably lower concentrations and do not show exceedances that correlate with Cowtown. ADEQ conc ludes that this demonstrates that the emissions do not travel far and are from very local ized sources. 5

EPA agrees with ADEQ’s conclusion that the PM 2.5 concentrations monitored at Cowtown are strongly influenced by local sources. However, wit h regard to the extent of the nonattainment area, EPA notes that CAA section 107(d)(1)(A) defines a nonattainment area a s one that does not meet, or that “contributes to” ambient air quality in a nearby area that does not meet the NAAQS. The mere absence of violating monitors in o ther locations does not establish that sources in those locations are not contributing to nearby violations. The pollution rose in our TSD (Figure 11) indicates that most PM 2.5 exceedances in this area occur when resultant wind is from the southwest to southeast. Figure 3 in our TS D and Figure 5-A below show that emission sources of concern (e.g., feedlots and geologic soi l sources such as agriculture and unpaved roads) are located in areas to the southwest and so utheast of ADEQ’s recommended nonattainment area. Thus, the emissions inventory d ata and related maps do not support

3 July 13, 2010 ADEQ TSD, p 13.

4 Ibid, p 17

5 Ibid p 14.7

Arizona’s recommended boundaries, but rather argue for a larger nonattainment area including the portion of the south-southwestern half of the c ounty that contains emissions sources (e.g., feedlots and agriculture) similar to those included within ADEQ’s proposed boundary.

EPA’s final boundary includes areas for which emiss ions data show a relatively high prevalence of the types of sources (e.g., feedlots and agricul ture and unpaved roads (geological soil)) contributing the most to the PM 2.5 emissions at Cowtown. See Figure 5-A.

Air Quality Data

Both Arizona’s recommended nonattainment area and E PA’s proposed nonattainment area encompass the location of the violating monitor. Ho wever, section 107(d)(1)(A) of the CAA requires that areas that are contributing to violat ions in a nearby area must also be included

within a nonatttainment area. While feedlot soil ma kes up a large portion of the PM 2.5 mass measured at the Cowtown monitor, geologic soil also contributes to high concentrations of

PM 2.5 . EPA believes that Arizona’s recommended boundary excludes similar feedlot and geologic soil sources that are contributing to viol ations at the Cowtown monitor. To ensure that contributing sources are included in the nonattainm ent area, EPA has finalized a nonattainment area boundary that extends farther to the south and west of Arizona’s recommended boundary. See Figure 5-A. By inclusion of these sources with in the boundaries of the nonattainment area, Arizona will be evaluating these sources for potent ial controls in its attainment plan in order to provide for expeditious attainment of the NAAQS in this area.

Population Density and Degree of Urbanization

EPA evaluates population data because it can give a n indication of whether it is likely that population-based emissions in an area are contribut ing to PM 2.5 levels at the violating monitor. In addressing this factor, ADEQ’s technical report notes that 95 percent of the Pinal County population lives along the Interstate-8 and Interst ate-10 corridors (page 19). These corridors lie

to the south and east of Arizona’s recommended nona ttainment area. The executive summary of ADEQ’s technical report asserts that the Governor’s recommended boundary “includes the population most affected by high PM 2.5 concentrations,” but lacks supporting information. See Table ES-1. In any event, the boundary of the nonat tainment area must include areas that are experiencing violations of the air quality standard , as well as those nearby areas that contribute to those violations. In this case, the violations app ear to be largely driven by emissions from cattle feedlots and agricultural activities that are inver sely related to population density. As a result EPA concludes that population density is not signif icant factor in determining the geographic extent of the nonattainment area given the facts an d circumstances of this particular area.

Traffic and Commuting Patterns

EPA and ADEQ agree that traffic and commuting patte rns are not significant factors in determining the geographic extent of the nonattainm ent area given the facts and circumstances of this particular area.8

Growth Rates and Patterns

Because cattle feedlots, agriculture, and unpaved r oads dominate the sources included in the emissions inventory that are contributing to violat ions in this area, EPA does not believe that growth rates and patterns are a significant factor with respect to determining the boundary of this nonattainment area. ADEQ, by pointing to the proxim ity of Indian country and publicly-owned lands as a buffer from contiguous development, reac hes the same conclusion.

Meteorology

In developing its boundary decision, EPA also consi dered additional meteorological evidence submitted by ADEQ. Analyses performed by ADEQ are discussed in ADEQ technical report section 3.4 on Air Quality Data (pages 11 - 17) and in Appendix B. These included source apportionment, HYSPLIT trajectories, consideration of how a plume from a distant source would affect Cowtown and other monitors, comparison of co ncentrations between different 24-hour

PM 2.5 monitoring sites, and comparison of PM 10 and PM 2.5 temporal variation. Some of these analyses are similar to, and support, the conclusio ns reached by EPA discussed above, i.e. that Cowtown exceedances appear to be driven by a differ ent mix of sources than those affecting the other monitoring sites in the area, with the domina nt component caused by local sources. However, EPA does not believe these analyses provid e sufficient basis for reducing the size of the nonattainment area proposed by EPA. EPA has al ready limited the boundary to a portion of Pinal County that contains the sources that appear to be contributing to the violations at the

Cowtown monitor. Further reduction in the size of the boundaries would result in the exclusion of sources of the types that available evidence ind icates contribute to the violations.

The source apportionment data, based on the 2003 PC AQCD study using the Chemical Mass Balance model, provides evidence that feedlots are the most important emission source for Cowtown exceedances, and are responsible for 49% of the monitored value. Samples from other monitoring sites have a far lower proportion of fee dlot emissions. ADEQ uses this as evidence of Cowtown's uniqueness, and also to support their pos ition that emissions from feedlots are not widely transported. However, the same source appor tionment analysis shows a soil contribution of 24% at Cowtown. This soil contribution may have come from locations beyond the immediate vicinity of the Cowtown monitor. In sett ing area boundaries, the CAA directs EPA to include locations that likely contribute to exceeda nces at the violating monitor(s). EPA does not believe that the 2003 PCAQCD source apportionment s tudy supports a smaller area than that proposed by EPA.

ADEQ also performed a back trajectory analysis usin g the HYSPLIT model for seven different

PM 2.5 exceedance days (ADEQ TSD Appendix B, pp.17-25). Air parcels arriving at the Cowtown monitor were traced back in time 6, 12, 18, and 24 hours to find their origin and to check for emission sources the parcels may have pas sed over. ADEQ concludes that in all cases

there are no obvious PM 2.5 sources along the transport path. It is not clear what criteria ADEQ applied to check for sources, but even if there are no apparent point sources, many of the trajectories do pass over agricultural land and ove r other areas of open land. Both agricultural and open land could be contributing PM 10 , PM 2.5 , and PM 2.5 precursors to the air parcels arriving at Cowtown. For over half the trajectories, parcel arrival times (indicated by short line segments9

on the graphs of hourly PM 10 over time, which accompany each HYSPLIT map) corre spond to

elevated PM 10 concentrations. 6 EPA does not believe that the HYSPLIT evidence de finitively proves or disproves the hypothesis of a local-only contribution to exceedances. Nor does EPA believe that the HYSPLIT analyses undermine the are a boundary proposed by EPA.

Appendix B of ADEQ’s technical report also discusse s (pages 26 - 32) the width of a plume from a hypothetical source 100 kilometers away, sho wing that it would be so wide by the time it reached Cowtown and Casa Grande, that it would like ly affect monitors at both locations. ADEQ points out that this analysis is inconsistent with the fact that only the Cowtown monitor experiences exceedances. ADEQ presents the plume a nalysis as evidence that medium- and long-range transport are not responsible for the Co wtown exceedances. EPA agrees that this analysis provides some indication of the lack of di fference in monitor impact from a somewhat distant point source. However, the longest dimensi on of EPA’s final boundary is approximately 40 km, which is substantially less than the 100 km examined by ADEQ. Finally, EPA is not claiming that emissions from moderately distant loc ations dominate Cowtown concentrations,

but rather that these emissions contribute to monit ored violations of the air quality standard. Thus, EPA does not agree that the ADEQ analysis jus tifies reducing the final area boundary.

Other analyses performed by ADEQ show that concentr ations at Cowtown are statistically significantly different than those at other monitor s (Appendix B, pages 28 - 31), and that there is a strong correlation between PM 2.5 and PM 10 at Cowtown (Appendix B, pages 32 - 34). EPA agrees with the findings that the same sources, lik ely local feedlots, constitute the major portion

of both PM 2.5 and PM 10 emissions at the Cowtown monitor and supports the conclusion that

Cowtown has a different mix of sources than the oth er 24-hour PM 2.5 monitoring sites in Arizona. However, as shown by the source apportion ment data and EPA's analysis of the diurnal

variation of PM 10 and wind speed for certain exceedance days where h igh PM 10 is associated with high wind speed (e.g., 02-23-2007, 04-12-2007, 10-09-2007), there appears to be a soil contribution not associated with nearby feedlots, a nd there remains the potential for dust transport from moderately distant land. While ADEQ has presented evidence for a localized source causing the PM 2.5 exceedances, EPA believes that there is some trans port contribution from other locations within the final area boundary

.

Geography and Topography

The ADEQ technical report section 3.3 (p.11) on Geo graphy and Topography discusses the same mountain ranges discussed in the EPA TSD. EPA beli eves these mountain ranges are partial barriers to the transport of air pollution. Other than the Estrella Mountains to the north, ADEQ did not characterize these ranges as barriers to tr ansport. However, the absence of barriers does not support an area smaller than that recommended b y EPA. The ADEQ technical report also presents concentrations below the NAAQS at the Apac he Junction and Casa Grande monitors and interprets this as evidence that the influence of emissions near Cowtown does not extend for

6 Hourly PM 2.5 data are not available for the Cowtown site, but h ourly PM 10 data are. Because the PM 2.5 at the Cowtown site is mainly from sources associated with primary PM 10 (74% feedlot material and soil per ADEQ source apportionment), there is a correlation betwe en 24-hour PM 10 and PM 2.5 levels at the Cowtown site. As a result, PM 10 data can provide useful information about PM 2.5 . See page 26 of EPA’s TSD and Appendix B, page 11, figure 6 of ADEQ’s technical report.10

any significant distance from Cowtown. In setting area boundaries, however, EPA includes locations that may contribute to exceedances at Cow town, rather than those locations without violating monitors to which Cowtown sources may con tribute. EPA believes that the additional evidence presented by ADEQ for this factor does not support a smaller boundary area than proposed by EPA; however, upon further analysis we have concluded that the topography of the Table Top Wilderness Area would inhibit the transpo rt of air pollution from the state lands located immediately to its south, and have revised the nonattainment area boundary accordingly.

Jurisdictional Boundaries

The State, lacking jurisdiction over tribal lands, properly excludes Indian country from its recommended nonattainment area. It also notes that, “since the violating monitor lies within the boundaries of the City of Maricopa and near Casa Gr ande, the incorporated boundaries of these municipalities were taken into account. The [State’ s] recommended nonattainment area includes almost all of the City of Maricopa and excludes all of Casa Grande.”

The northern portion of the eastern boundary of EPA ’s nonattainment area partially coincides with Arizona’s proposed boundary. However, EPA’s bo undary includes all state lands within T5S, R4E, whereas Arizona’s proposed boundary exclu des section 12, 13, 24, and 25 of T5S, R4E. Although ADEQ’s technical report does not expl icitly make the connection, it appears that

these sections were excluded out in order to avoid including portions of Casa Grande in the

nonattainment area.

Because the sources that are the primary contributo rs to PM 2.5 are regulated by the State and County, rather than by municipalities, EPA does not believe the inclusion of a portion of Casa Grande within the nonattainment area (or conversely , the exclusion of a portion of the City of Maricopa as Arizona has proposed), presents jurisdi ctional challenges. Further, municipal boundaries are subject to change. As a result, in t his case EPA does not believe that municipal boundaries are a major factor in determining the bo undary of the nonattainment area. By including all state lands within T5S, R4E, addition al agricultural lands, some of which lie within Casa Grande’s incorporated boundaries, are included in the nonattainment area.

Level of Control of Emissions Sources

EPA noted in our TSD that we were not aware of any information regarding emissions controls that would have relevance to assessing source contr ibution to the monitored violations. As a result, the level of control of emissions sources w as not considered to be a factor in determining the boundary of the nonattainment area. ADEQ’s tech nical analysis presented general information regarding air quality modeling and moni toring, and permitting and inspection programs, but did not use that information to suppo rt its proposed boundary.

Conclusion

Based on our review of the Governor July 19, 2010 l etter and ADEQ’s technical report, EPA has made a revision to the southwestern portion of the originally proposed nonattainment boundary. We have determined that the Table Top Wilderness Ar ea, which occupies most of the11

southwestern corner of our proposed nonattainment a rea, along with state lands to the south of the wilderness area, are not likely to cause or con tribute to the exceedances measured at the Cowtown monitor. As a result, the final nonattainme nt area boundary excludes this area. Figures

4-A and 6-A illustrate the revision to the nonattai nment area boundary.12Figure 3-A. Emissions Sources and Revision to EPA’s Proposed PM2.5 Nonattainment Area Boundary.Tohono O'OdhamTribal LandsTable TopWilderness AreaWest Central PinalPM2.5Nonattainment Area - FINALPinalCountyMaricopaCounty7S 2E8S 3E8S 2E7S 3E6S 2E6S 3E7S 1E8S 1E6S 1E8S 4E7S 4E6S 4E9S 2E9S 3E9S 1E9S 4E8843470 21 MilesAIR1000054_6a 28 October 2010Sources: Arizona Geodata Portal (2010),EPA (2010), ESRI (2010) TANA (2006).Additional Cattle OperationsFeedlotsDairiesFinal EPA PM-2.5 NAAProposed EPA PM-25 NAAUnpaved RoadsAgricultureWildernessTownship and RangeTribal landsCounty boundary2002 Daily Truck Traffic0 - 2,0002,001 - 5,0005,001 - 10,00010,001 - 25,0002002 Daily Traffic0 - 2,0002,001 - 5,0005,001 - 10,00010,001 - 25,00025,001 - 282,000PinalCounty13Figure 4-A. Detail of Revision to EPA’s Proposed PM2.5 Nonattainment Area Boundary.Tohono O'OdhamTribal LandsTable TopWilderness AreaWest Central PinalPM2.5Nonattainment Area - FINAL7S 2E8S 3E8S 2E7S 3E7S 1E8S 1E6S 3E6S 2E8S 4E7S 4E6S 1E9S 2E9S 3E9S 1E9S 4EPinalCountyMaricopaCounty8840 21 MilesAIR1000054_7a 28 October 2010Sources: Arizona Geodata Portal (2010),EPA (2010), ESRI (2010) TANA (2006).Final EPA PM-2.5 NAAProposed EPA PM-25 NAATownship and RangeSectionsQuarter SectionsWildernessTribal landsCounty boundaryUnpaved RoadsPinalCounty14Figure 5-A. Final West-Central Pinal PM2.5Nonattainment Area and Sources of Emissions.West Central PinalPM2.5Nonattainment Area - FINALPinalCountyMaricopaCountyGila RiverTribal LandsAk-ChinTribal Lands81023884347238347052.5 MilesAIR1000054_10 4 November 2010Sources: Arizona Geodata Portal (2010), AQS (2010)EPA (2010), USDA (2006), ESRI (2010) TANA (2006).Additional Cattle OperationsFeedlotsDairiesViolating PM-2.5 monitorAttaining PM-2.5 monitorUnpaved RoadsFinal EPA PM-2.5 NAAProposed ADEQ PM-2.5 NAAAgricultureDeferred Tribal LandsCounty boundaryIncorporated City BoundariesPinalCounty15Figure 6-A. Pinal County and West-Central Pinal PM2.5Nonattainment Area.West Central PinalPM2.5Nonattainment Area - FINALPinalCountyPimaCountyMaricopaCountyGilaCountyGrahamCountyGila RiverAkChin0 5 102.5 MilesAIR1000054_8a 28 October 2010Sources: EPA (2010), ESRI (2010),TANA (2006).Proposed EPA PM-25 NAAFinal EPA PM-2.5 NAACounty boundaryTribal lands