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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX

75 Hawthorne Street

San Francisco, CA 941 05-3901

OCT 02 2014

Mr. Steven Estrada, Environmental Manager

Soboba Band of Luiseflo Indians

P.O. Box 487

San Jacinto, California 92581

Dear Mr. Estrada:

This letter responds to the Sohoba Band of Luiseño Indians’ (Soboba Band) September 23, 2014 request

for consultation regarding EPA’s recent designations for the 2012 PM2.5national ambient air quality

standard (2012 PM2.s standard). On September 30, 2014, EPA participated in a conference call with you

regarding the 2012 PM2.5standard designations to discuss the Soboba Band’s questions and concerns.

During our September 30, 2014 discussion, we described the Clean Air Act’s designations process for

the 2012 PM2.5standard, reviewed the history ofthe PM2.5standard in the southern California area, and

explained the implications ofthe nonattainment designation for the Soboba Band.

Multiple Factors Considered:

As noted in our call, EPA included the Soboba Band’s Indian country in the South Coast Air Basin,

which EPA intends to designate nonattainment for the 2012 PM2.5standard, after considering multiple

factors: 1) air quality, 2) emissions and emissions-related data, 3) meteorology (weather/transport

patterns), 4) geography/topography (mountain ranges or other air basin boundaries) and 5) jurisdictional

boundaries. With respect to these five factors, it is important to note that nonattainment areas are

intended to include areas that are violating the standard, as well as areas that may cause or contribute to

the violation. The two air monitors that measure PM2.5concentrations for regulatory use closest to

Soboba Band’s Indian country are a monitor in the city of Palm Springs and a monitor in the city of

Riverside. The San Jacinto Mountains fall between the Soboba Band’s Indian country and Palm Springs,

while there is no similar topographical feature separating the Soboba Band’s Indian country from

Riverside. The Riverside monitor and those near it measure some of the highest concentrations of PM2.5

in the nation. While emissions occurring in Soboba Band’s lands may be small, the dominant

meteorological patterns combined with the area’s topography contribute to transport ofPM2.s emissions

from the west to the east in the South Coast Air Basin (these patterns can be verified by looking at

monitored concentrations within the area). Finally, EPA weighed each of these factors in the context of

existing jurisdictional boundaries and determined that the Soboba Band’s Indian country should he

designated nonattainment as part of the South Coast Air Basin for the 2012 PM2.5standard as it has for

each of the prior particulate matter standards.

Implications of the Soboba Band’s designation:

With the 2012 PM2.5standard designation, the Soboba Band will not be responsible for any new

planning activities. The required planning activities are performed by the South Coast Air Quality

Management District or the Southern California Association of Governments. In addition, given the

South Coast Air Basin’s current classification under the PM2.sstandard, permitting thresholds (presently

Printed on Reev led Paper
set at 100 tons per year for new sources) on the Soboba Band’s lands will not change, unless the area

fails to attain the PM2.s standard within the prescribed timeframe.

Thank you for the opportunity to better understand the Soboba Band’s concerns. I hope this letter helps

to clarify our designations process. In the event that the Soboba Band has additional questions or

concerns, please contact me at (415) 972-3183 or Ken Israels of our Grants and Program Integration

Office at (415) 947-4102.

Sincerely,

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E1izabethJ. Adams —

DeputyD1irector, Air Division