Attachment A 

Request to Create a Nonattainment Area for the Morongo Indian 

Reservation 

EXECUTIVE SUMMARY 

On November 6,2003, EPA modified the boundaries of nonattainment areas in Southern 

California so that the Morongo Reservation "moved" fiom the Coachella Valley 

Nonattaiirment Area within the Salton Sea Air Basin to the South Coast Air Basin, which 

had a more restrictive ozone attainment designation. The State of California petitioned 

EPA on September 27, 2007 to "bump up" the ozone ironattainnlent designation for the 

South Coast Air Basin from "severe-1 7" to "extreme." 

With regard to jurisdictional boundaries, EPA did not acknowledge the existence of the 

Morongo Reservation as a separate, sovereign jurisdictioil wllen the nonattahnent area 

boundary was changed in 2003, and did not recognize the major inlplications for the 

Tribe of moving the area boundary. The Tribe's ecoiloniic and governmental interests, 

specifically its inherent authority with respect to reservation air quality planning and its 

nascent regulatory and permitting authority under the Tribal Autllority Rule, were 

supposed to be protected by the EPA until the Tribe could fbrmally assume these 

responsibilities. 'This was not done, as evidenced by the lack of EPA consultation with 

the Tribe during the 2003 boundary change rulemaking, as required under Executive 

Order 13 175 and the fderal trust responsibility. 

The Morongo Band of Mission Indians (Tribe) requests that EPA create a Morongo 

Noilattaininent Area that is geographically identical to the reservation. If that is not 

approvable for some valid reason, in the alternative the Tribe requests that EPA move the 

western boundary of the existing Coachella Valley Nonattainment Area to include the 

Morongo Resewation. Leaving the Molongo Reservation within tl~e South Coast 

Nonattainment Area will impose additional, unanticipated delays in developing 

Morongo's air program, including the Tribe's plan to implement a tribal air pertnit 

progranl for minor sources within the next year. First, by reducing the major source 

"potential to emit" thresh0 ld for ozone precursor (i. e., NOx and ROC) emissions fiom 25 

tpy to 10 tpy under the 8-hour average ozone standard, the reclassification will increase 

the nuinba- of facilities potentially subject to Nonattainment New Source Rcview 

(NNSR) requirements, thus increasing the use and cost of Morongo staff resources, as 

well as facility resources. Sewitd, the number of future facilities subject to Title V 

would be significantly increased if the threshold of25 tpy is reduced to 10 tyy. Finally, 

under the cui~ent nonattainment area designation, the threshold for the applicability of 

General Confornlity requirements is similarly 10 tyy, requiring many more projects to 

dcmonstratc that their emissions of criteria pollutants will not impede progress toward 

attainment with national ambient air quality standards. 
For both existing facilities and future facilities subject to NNSR, there is currently no 

system in place through which such facilities can obtain emission reduction credits. 

Unless EPA allows such sources to use emission reduction credits fiom the adjacent air 

basins, either through its own program or through a tribal permitting program, such 

facilities will be placed at a disadvantage relative to similar facilities operating outside of 

the Reservation. 

Based on the nine factors suggested in EPA guidance, analysis of the relevant technical 

data support establishment of the Momngo Reservation as its own nonattainment area. If 

EPA believes that a separate nonattainment area is not legally defensible, then the 

Morongo Reservation should be made a part of the Coachella Valley Nonattainment 

Area. The factor ofjurisdictional boundaries suggests that the reservation should 

logically be its own nonattainment area The factors pertaining to low population density 

and lack of urbanization, meteorology, geography, hydrology, and level of emission 

source control show that the reservation is substantially different than the South Coast 

Air asi in,' and holds more in common with the Coachella Valley Nonattainment Area. 

The remaining factors dealing with air quality, causes of nonattainment, lack of local 

emission sources, low level of local trac, and growth rates ae neutral on commonality 

with either the Coachella Valley or South Coast Nonattainment Areas, and hence EPA 

should treat these factors as supportive ofthe tribal request to make the Morongo 

Reservation its own nonattainment area. 

INTRODUCTION 

On November 6,2003, the U.S. Environmental Protection Agency (EPA or Agency) 

modified the boundaries of the Salton Sea Air Basin (SSAB), so that the Morongo 

Reservation "moved" from the Coachella Valley Nonattainment Area in the SSAB to the 

South Coast Air Basin (SoCAB), which had a more restrictive ozone attainment 

designation. One of the important parameters that this action changed for the Morongo 

Band of Mission Indians (Tribe) is that the major source definition threshold droppcd 

horn the previous 25 tons per year (tpy) level down to 10 tpy. That change to the lower 

major source threshold is fiuther exacerbated by the September 27,2007 request fiom the 

South Coast Air Quality Management District and the State of california2 that EPA 

"bump up" the nonattaimnent designation of the SoCAB fiom "severe-1 7" to "extreme" 

with respect to the 8-hour average ozone standard. 

Keeping the Morongo Reservation hi a nonattainrnent area with such a restrictive major 

source threshold means that the Tribe cannot implement a meaningful Minor Source 

permitting program because the regulation would be applicable only to a small set of 

potential future emitting sources whose emissions would be lower than 10 tpy ofboth 

I 'Ihe South Coast Nonattainment Area is geographically identical to the South Coast Air Basin. 

%e South Coast Air Quality Managanent Distlict described the request in the June 1,2007 Roardapproved 2007 Air Quality Management Plan, and initiated the requcst September 27,2007. The 

Califon~ia Air Resources Board (ARB) passed Resolution 07-4 1 on September 27,2007 to forw~d the 

request for redesignation to EPA. 
NOx and VOC. Several additional years will be needed for the Tribe to develop a Major 

Source permitting program and gain approval fir such a program from EPA. During this 

interim period, the Tribe would not have permitting authority over its own Morongo 

Casino Cogeneration Plant, which now operates under EPA's Part 7 1 Title V permitting 

authority. 

Tl~e purpose of this document is to present the logical and technically based rationale tbr 

EPA to create a Morongo Nonattainment Area. It will be shown that the reservation has 

substantial diffwences fiorn the South Coast Air Basin and warrants its own 

nonattainment area. It makes no sense for the reservation to remain inside the South 

Coast Nonattainment Area, which is the principal source ofthe emissions that cause the 

monitored violations of the ozone National Ambient Air Quality Staadards (NAAQS) on 

Tribal lands, and EPA has authority under Clean Air Act Section 11 0(k)(6) to create a 

Morongo Nonattainment Area. At a minimum, EPA should adjust the Coachella Valley 

Nonattainment Area boundary to include the Morongo Reservation. 

RATIONALE 

The following discussion is organized according to the nine factors, taken fkom USEPA 

guidance. 

Factor I : "Air aualitv data" 

Ozone, generated by atmospheric reactions of its precursor einissions ofNOx and VOC 

over periods of hours, is by its nature a regional pollutant. High levels that exceed the 8- 

hour ozone NAAQS are widespread throughout the SoCAB, an4 because of'the 

overwhelmingly dominant role of transport: are also widespread throughout the 

Reservation and the Coachella Valley Nonattainment Area, sls well as the rest of the 

SSAB. 

As can be seen in Figure 1, the average annual number of exceedances of the current 8- 

hour ozone NAAQS is highest at the Redlands monitoring station, and similarly high at 

the two stations west on the SOCAB' side of Redlands and four of the five stations to the 

east of Redlands (see Figure 2 for the locations of the monitoring stations). The 1 1-year 

average of 32 exceedances measured at the Indio monitoring station are substantial, but 

only half the number measured at the other monitoring stations. Figure 3 shows that the 

relative magnitude and temporal trends of the number of ozone exceedances are 

USEPA. Apes Designutiom for the 2008 Revised Ozone National Ambienr Air Qudi{v S~undurds, 

memorandum from Robert J. Meyers, Principal Deputy Assistant Administrator, Office of Air and 

Radiation, to Regional A&ainistrators, Dece~nber 8,2008. 

South Coast Air Quality Management District (SCAQMD). Air Quality Management Plan, Chapter 8 .- 

Future Air Quality - Desert Nonattainment hens, 1997, httpr//www.aqmdgov/aqmp/97aqmp/chapter,~/mc~I<JJ&. htfPll. 

The Morongo Reservation and monitoring station are currently located in the South Coast Air Basin and 

South Coast Noiutttainment Area. 
comparable for most of the stations, especially in 2005 when the highest number of' 

exceedances were recorded at Banning, Palm Springs, Joshua Tree, and Riverside. 

Figure 4 shows that the average annual maximum 8-hour ozone concentration is 

relatively uniform between the monitoring stations, and the highest occurs at Redlands. 

Figure 5 shows the relatively unifbrm and synchronous temporal changes between the 

stations from year to year. Similarly, Figures 6 and 7 show the same uniformity between 

stations and fiom year to year of the annual 4" highest 8-hour ozone concentrations, 

respectiveIy. 

~ecause the spatial pattern of these stations covers both the east side of the SoCAR and 

Coachella Valley Nonattainment Area, the magnitude and temporal pattern of ozone 

concentration suggest that the Morongo Reservation should be established as its own 

nowattainment area. 
Figure 1. Average Annual Number of Excedances of the 8-Hour Ozone 

NAAQS (0.075 ppm) from 1998-2008 

l Riverside Perris BB Redlands .Banning I# Morongo* @ Palm Springs 199 Joshua Tree NM*' @ lndio 

j 

South Coast Monattainment Area Coachella Valley Nonattainment Area 

i +-------------------------- ---I---------------- 90 .\"..."." - --" ,-- 

.) 

* Data forthe Morongo siteonty existfor 2006-2W8. 

* Full site name isloshua Tree National Monument (A05 site #0607190023. 

Notes: The vertical line acmssthe topof each barrepresene onestandarddeviationaround the arthmetic mean. 

The Joshua TreeMational Monument data for 203 wereexduded bmuse theywere very incmsistent with the other yearsand sitesand appear erroneous. 

Figure3. Average Annual Number of Exceedances of the 8-Hour Ozone 

NAAQS (0.075 ppm) by Year Normalized to Redlands 

-- - .."..*." - - -" " 1-60 - -- - - --- 

........................ 0 .oo .r-7-. TI- 

--Riverside 

-B-Redbnds 

-$+?-Banning 

44- Morongo 

--*Joshua Tree NM 

+Palm Springs 

Notes:The Perrlsdata wereexdded due tohlghvolatjlityof theconmtrationsfrom year-to-year, makingcomparisomwiththeothersitesd~fficult. 

me JoshuaTreeNMdatafor ZOQI wereexcluded becausethey were very inconsistent withtheother yearsand sitesand appear erroneous. 

The Indiodata wereexcludeddueto themuch lower number ofexceedancesand thelowcorrelationwiththeothers~tes. 
Figure 4. Average Annual Maximum 8-hour Ozone Concentration from 1998-2008 

l Riverside gl Perris @ Redlands l Banning B Morongo* @ Palm Springs Joshua Tree NM** @ lndio 

160 ....................... I " " I 

South Coast Nonattainment Area Coachella Valley Nonattainment Area 4----------------- ---- i-----------

+ j 

* Data forthe Moronga siteonh/exlstfor 20C16-2008 

* Full wte name isJc6huaTree National Monunent(AQZ site#U60719002). 

NQes:lhe vertical line acrossthe topof each barrepresentronedandarddeuiationaround the arlhmetic mean. 

The Joshua Tree National Monument data for 2031 wereexduded because theywe~every irronsistent with theotheryearsand sites and appearerroneous. 
'~~Io~uoJJ~ Jeadde pue sq!s pue SJeah~wl0 aqjq8~ walgsuox! A~ah aam Aaq~asnmaq papnlnaaJaM TOOZ JoJeIeP WN aaJ1 enqsor au 

~qm!y!psa~!sjq~oaqjq~!Mwosyedcuo~Bu!qew ~~~~-~J-J~~~~oJ~su~~wu~uo~J~~~o~~~&~~o~@!~o~ snp PaPnPxaan* elePgJJad aU:saloN 

8002 LOO2 9002 SO02 PO02 FOOZ ZOOZ T 002 0002 6665 8661: 

! ........ i A "L L 

! t 00.0 I 

-..-..--.,,.. .....................-.. .--I ovo E 

3 

1 I 0, 
Figure 6. Average Annual 4th Highest 8-hour Ozone Concentration Averages 

from 1998-2008 

Ei Riverside aD Perris @ Redlands lBl Banning Bi Morongo* I Palm Springs I Joshua Tree NM** @ lndio 

160 .r......---.--- 

i 

i South Coast Nonattainment Area ellavalley Nonattainment Area 

I ---------------- " --..-.. - -- ............... "."".".-- 

Data for the Morongo site only exist for 2006-2008 " Full site name isJoshua Tree National Monument(AQSsite #060714)02). 

Notes:The verticalline acrossthe topof each barrepresentsonestandarddeJatlonaround the artthmetk mean. 

The JoshuaTree National Monument datafor 2Mn wereexduded bemuse theywere veryinconslstentwhh the other year sand sites and appear erroneous. 
Figure 7. Annual 4th Highest 8-hour Average Ozone Concentration 

Normalized to Redlands 

E 

: 

8 1.00 U) 

u 

c -+-Riverside a 

G +Redlands 2 

o 0.80 w +Banning C 

0 

f -4- Morongo - 

E --" .......... .- .......................................................... --*Joshua Tree NM 

9 0.60 

Palm Springs 

-+- lndio 

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 

Notes:The Perrisdata were excluded due tohighvolatility oftheconcentrationsfrornyear-to-year, rnakingcomparlsons wlththe othersitesdlftlcult. 

The JoshuaTreeNM data for 2001 wereexcludedbecausetheyweix very inconsistent with the other year sand sitesand appear erroneous. 
Factor 2: ffEmissions data (location of sources and contribution to ozone concentrations')'' 

Due to the sparse population of the Morongo Reservation, the limited emissions f?om the 

few sources on the Reservation are close to only a few nearby receptors. This same 

sparse distribution of emission sources and nearby receptors characterizes the other 

Indian reservations and communities located throughout most of the SSAB. The greater 

Palm Springs area, which contains the densest population within the SSAB, is itself 

relatively isolated fhm other SSAB communities, and covers a small fiaction of the 

SSAB's surface. Far different is the close proximity ofthe dense residential areas of the 

SoCAB to transportation, commercial, and industrial emission sources clustered in the 

urban centers of the SoCAB, including not only the Los Angeles CMSA, but also the 

nearby Riverside-San Bernardino-Ontario Metropolitan Statistical Area. 

Table 1 presents a comparison of emissions fiom the Morongo Reservation and two 

portions of Riverside County in the SoCAB and SSAB, separated into stationary, area, 

and mobile source categories. The emissions in both the SoCAB and SSAB portions of 

Riverside County are well in excess of the emissions on Tribal lands and, as a result, 

these data suggest that the Morongo Reservation should be established as its own 

noilattahment area. 
Factor 3: "Po~ulation de~lsitv and demee of urbanization (including commercial 

development)" 

The Morongo Band of Mission Indians has a low population (see Table 2), a low 

population density throughout the reservation, and a general lack of urbanization. These 

same characteristics of the Morongo Reservation are found throughout much of the 

Coachella Valley Nonattainment Area and the larger SSAB, exccpt within the 

fast-growing retirement cities such as Palin Springs and PaInl Desert. As one moves west 

from the Morongo Reservation, population density and degree of urbanization ~apidly 

increase upon reaching the nearby Riverside-Sari Bernardino-Ontario Metropolitan 

Statistical Area, and reach the highest levels found in the Los Angeles CMSA upon 
moving furtl~er west towards the coat. Table 2 sl~ows the population density of the 

Morongo Reservation, Coachella Valley, Riversidesan Bernardino-Ontario Metropolitan 

Statistical Area, Riverside County, Los Angeles County, and Los Angeles-Long BeachSanta Ana Metropolitan Statistical Area The population density on the reservation is far 

lower than that in any of the other nearby geographical areas, and is closest to that found 

in the Coachella Valley within the Coachella Valley Nonattainment Area. Thus, from the 

perspective of population density and degree of urbanization, the data support 

establishment of the Morongo Reservation as its own nonattainment area. 

Reservation. Growth rate based on estimate of 375 residences and annual increase of 2-3 (mail fiom 

Director, Environmental Protection Department, Fehy 17,2009). 

Coachella Valley, California, h~~:l/www.city-data.com/citylCoachella-Valley-Cali~mia.html 

"Coachella Valley Fxonnrnic Partnership, Poptrlation Trends, data br 2005, 

http://cvq.comlpop-traids.dim1. 

MSA - Metropolitan Statistical Area. 

US Cwsus Bureau. QuickFacts, http:l!quickf8cts/census.gov. 

'USEPA. Letter fio~n Wayne Nastri, Ado~inistrator, Region 9, to Martin Robert, Chairperson, Moi-ongo 

Bald of Mission Indians, August 21,2008, 

http://www.epa.gov/prndesignationsl2006b~andarddrec~ettersrT~M0~ongo~Band~of~ Mission-Indians-EPA 

Factor 4: "Traffic and commutinp vattern" 

Traffic and commuting throughout most of the Morongo Reservation are at low levels, 

while non-tribal regional traffic and commuting are dominated by the presence of 

Interstate 10 crossing through the Banning Pass on the southern boundary of the 

reservation (see Table 3). Similarly, traffic and commuting levels throughout most of the 

SSAB are light, but heavy traffic is concentrated on 1-1 0, especially where it is adjacent 
to thc Palin Springs to Palm Desert con-ictor of resort hotels and residentiaI developments. 

Moderate levels of traffic and commuting are found in the SSAB along State Highways 

86 and 1 1 1 (see Table 3) running from the north end of the Salton Sea southeast dong the 

west and east sides of the sea, respectively, and into Imperial County. 

The SoCAB, in comparison, is characterized by the highest levels of traffic and 

commuting found in the nation. These high levels are found throughout the basin, 

including on the road system in nearby San Bemardino and Riverside. In fact, the eastwest traffic on interstate-level highways 1-10, SR60, and SR91 is concentrated onto the 

1-10 alone at the east end of the SoCAB because Banning Pass is the only major east exit 

fioin the basin into the SSAB. Table 3 provides traffic counts from several key roads in 

the geographical areas under consideration. The low levels of trafic throughout the 

reservation are: Inore consistent with the lower levels of traffic found on non-fi-eeways in 

the SSAB and the SOCAB (e.g., see lower levels of travel observed on SH-86 and 

SH-I 11 in the SSAB and SH-74 in the SoCAB). Freeway traffic levels are much higher 

than non-freeway traffic levels in both basins. 

I Avemge &i!y Truck Trqffic on 

Factor 5: "Growth rates and oattems" 

Both the Morongo Reservation and the adjacent Coachella Valley are mostly open space, 

containing relatively isolated communities connected by Interstate 10 and a few other 

major roads. Because both areas are home to only a few iildustries, their growth is tied to 

infrequent special developments such as the Morongo Casino and retiree residential 

projects. 

As can be seen in Table 2, population growth has been high throughout Riverside County 

on both sides of the Morongo Reservation, while low on the reservation (and in the 

Los Angeles-Long Beach-Santa Ana MSA). 
Factor 6: "Meteoroloev (weather/traflsp~-t patterns)" 

The meteorology and climatology of the Morongo Reservation, like its air quality, are 

dominated by the transport of air from the SoCAB, essentially the same as the 

continuation of the same transport through the Coachella Valley except that higher winds 

across the reservation result from its proximity to Banning Pass, which funnels air flow 

between the basins (i.e., relatively low speed daily sea breeze fiom the west, and 

relatively high speed wintertime Santa Ana desert winds from the east). The SoCAB is 

characterized by a substantial frequency of marine layer accompanied by calm winds 

under an inversion that leads to cooler temperatures, but higher concentrations of 

pollutants. The reservation rarely experiences the coastal marine layer, and the Coachella 

Valley and SSAB never experience it. Consequently, the Morongo Reservation has 

meteorology more similar to that of the Coachella Valley Nonattainment Area than to 

most of the South Coast Air Basin. Meteorology and atmospheric transport 

characteristics suggest that the reservation should be its own nonattainlnent area. 

Factor 7: "Geo~m~hy/to~omaph~ (mountain ranges or other air basin boundaries)" 

Because geography and topography are important factors in defining the boundaries of 

the SoCAB and SSAB, the Morongo Reservation clearly has far more in common with 

the SSAB. Most of the SoCAB is a coastal area heavily influenced by the proximity of 

the Pacific Ocean and generally westerly flow of air, accounting for the fiequent sea 

breezes during the day and strength of the marine layer. In contrast, the ringing of the 

SoCAB by the San Gabriel, San Gorgonio, and San Jacinto mountain ranges prevents this 

marine layer from affecting the environment that dominates from the Banning Pass 

through the Morongo Reservation and eastward-southeastward through the entire SSAB. 

On the large spatial scale of hydrologic regions, the Momngo Reservation is located 

within the Colorado River Basin Hydrologic Region, one of the ten hydrologic water 

study areas of Califoniia. The Colorado River Hydrologic Region has as its western 

boundary the crest of the San Bernardino, San Jacinto, Santa Rosa, and Peninsular 

Ranges, separating it completely fiom the South Coast Basin Hydrologic Region. 

Witlun this Region therc are planning areas and hydrologic units and subunits. The 

Morongo Reservation is situated directly within the San Gorgonio Hydrologic Subunit of 

the Whitewater Hydrologic Unit (WHU). The Whitewater River watershed (from which 

the Tribe derives its surGce water rights) is generally situated in Riverside County within 

the Coachella Valley Planning Area of the Colorado River Basin Regional Water Quality 

Control Board. The Whitewder watershed is generally defined by the boundaries of the 

WHU, as described in the Water Quality Control Plan for the Colorado River Basin, 

Region 7 (2006). The Whitewater River Watershed Municipal Stormwater Program 

Stonnw atcr Management Plan (200 1-2006) descriies the watershed as follows: "much 

of the watershed consists of sparsely populated mountains, desert, and agricultural lands. 

Urbanized areas are principally located on the valley floor between Banning and Indio 

along Interstate 10, and fkom Palm Springs to Coachella along State Highway 1 1 1 ." 
The western boundaries of thc above-refaenced planning areas and hydro logic units 

generally coincide with or are slightly to the west of the Morongo Reservation's western 

boundary, thus making it clear that, fiom a geographic and hydrological standpoint, the 

Reservation has more in common with the Salton Sea Air Basin than the South Coast Air 

Basin. 

This information serves to emphasize the connection between the Reservation and the 

Coachella Valley Area The Reservation and Coachella Valley luve surface water rights 

that derive from the same watershed (Whitewater) and share groundwater that flows in a 

generally southeasterly direction spilling fiom the San Gorgonio Basin aquifer into the 

Coachella Valley. 

Geography, topography, and hydrology information all suggest that thc reservation 

should logically be its om nonattainment area. 

Factor 8: "Jurisdictional boundaries (ex.. counties. air districts. existing nonattainment 

areas. Reservations. metropolitan olanninn organizations (MPOs)" 

The most important jurisdictional boundaries for nonattainment area definition and 

designation in the vicinity of the Morongo Reservation are those of the reservation itself, 

and that between the SoCAB and SSAB. The boundary between San Bernardino and 

Riverside Counties is located just a short distance north of the northern boundary of the 

reservation Jurisdictional aspects of the requested change in boundary are simplified by 

the following hcts: 

The reservation and the Coachella Valley Nonattainment Area are both located in 

the common jurisdiction of Riverside County; and 

Air quality management responsibilities of the South Coast Air Quality 

Management District for the South Coast Air Basin and the Coachella Valley 

Nonattainment Area will not change whether the reservation is located within the 

former or latter portions of the District's jurisdiction. 

Jurisdictional boundaries suggest that the reservation should logjcalty be its owl 

nonatt ainment area 

With regard to jurisdictional boundaries, EPA did not acknowledge the existence of the 

Morongo Reservation as a separate, sovereign jurisdiction when the nonattainment area 

boundary was changed in 2003, and did not recognize the major implications for the 

Tribe of moving the area bou~ldary. The Tribe's economic and governmental interests, 

specifically its inherent authority with respect to reservation air quality planning and its 

nascent regulatory and permitting authority under the Tribal Authority Rule, were 

supposed to be protected by tl~e Agency until the Tribe could formally assume these 

responsibilities. There was no EPA wnsuttation with the Tnbe during the 2003 boundary 

change rulemaking, as was required under Executive Order 13175 and the federal trust 

responsjbilit y. 
Factor 9: ''Level of control of emission sources" 

The key difference between the level of control of emission sources is that a source in the 

Coachella Valley portion of the SSAB must emit at least 25 tons per year of a 

nonattainment criteria pollutant or precursor to be subject to the inore stringent federal 

New Source Review and Title V federal operating permit requirements for a major 

source, compared to the requirements for a minor source, whereas sources in the SoCAB 

emitting only 10 tons per year or more of a nonattainment criteria pollutant or precursor 

are subject to the more stringent requirements for major sources. Mobile source emission 

control requirements are identical in the SSAB and SoCAB. As indicated above, air 

quality on the Morongo Reservation is dominated by transport from the SoCAB, where 

the 10 ton per year federal threshold applies. 

Large emission reductions are needed in the SoCAB to allow that air basin to make 

reasonable further progress towards attainment, and also to allow the SSAB to reach 

attainment because of the dominant role played by transport fi-om the SoCAB into the 

SSAB. Only a modest level of emission reductions is needed fiom sources on the 

Morongo Reservation and throughout the SSAB to prevent local sources ftom impeding 

reasonable further progress towards attainment. 

CONCLUSION 

Based on the nine kctors suggested in EPA guidance and analysis of the available data, 

the Morongo Reservation logically and technically should be its own Morongo 

No~lattainment Area tlut is geographically identical to the reservation. The factors 

pertaining to low population density and lack of urbanization, meteorology, geography, 

hydrology, and level of emission source control show that the reservation is substantially 

different than the South Coast Air and holds more in common with the Coachella 

Valley Nonattainrnent Area. The remaining factors dealing with air quality, causes of 

nonattainment, lack of local emission sources, low level of local traffic, and growtl~ rates 

are neutral on commonality with either the Coachella Valley or South Coast 

Nonattainrnent Areas, and hence it EPA should treat these factors as supportive of the 

tribal request to make the Morongo Reservation its own nonattainment area. 

Leaving the Morongo Reservation within the South Coast Nonattainment Area will 

impose additional, unanticipated delays in developing Morongo's air program, including 

the Tribe's plan to implement a tribal air permit program for minor sources within the 

next year. First, by reducing the major source "potential to emit" threshold kr ozone 

precursor (i.e., NOx and ROC) emissions from 25 tpy to 10 tpy under the 8-hour average 

ozone standard, the reclassification will increase the number of fkcilities potentially 

subject to Nonattainment New Source Review requirenlents, thus increasing the use and 

cost of Morongo staffresources, as well as facility resources. Second, the number of 

"fie South Coast Nonattainlncnt Area is geographically identical to the South Coast Air Basin. 
future facilities subject to Title V would be significantly increased because the threshold 

of 25 tpy is reduced to 10 tpy. Finally, reducing the threshold for the applicability of 

General Confbrmity requirements &om 25 tpy to 10 tpy would require many more 

projects to demonstrate that their emissions of criteria pollutants will not impede progress 

toward attainment with national ambient air quality standards.