# Air Resources Board
Mary D. Nichols, Chairman

1001 I Street· P.O. Box 2815 Linda S. Adams Sacramento, California 95812' www.arb.ca.gov Arnold Schwarzenegger

Secretaryfor Governor Environmental Protection

May24,2010

Mr. Jared Blumenfeld Regional Administrator United States Environmental Protection Agency Region 9 75 Hawthorne Street San Francisco, California 94105

Dear Mr. Blumenfeld:

TheAir Resources Board (ARB) requests thatthe United States Environmental Protection Agency (U.S. EPA) grantthe Western Nevada County 8-hour ozone nonattainmentarea a one-year extension ofthe 1997 8-hour ozone national ambient air quality standard (standard) attainment date.

On April 15, 2004, Western Nevada County was designated nonattainmentforthe federal 8-hour ozone standard and classified as a basic area. On January 16, 2009, U.S. EPA proposed to reclassify Western Nevada County undersubpart 2 as a moderate nonattainmentarea with an attainmentdate ofJune 15, 2010 (74 FR 2936). U.S. EPA has yettofinalize this ruling and has therefore notofficially set an attainment datefor this area. However, ARB believes that U.S. EPA could propose to grant a one-year extension now, pending taking final action to classifyWestern Nevada County as a moderate area with an attainment date ofJune 15, 2010.

U.S. EPA guidance specifiesthatthe design value for this standard is the three-year average ofthe fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitoring station. Since three full years ofair quality data are needed to demonstrate attainment, attainment by June 15, 2010, is based on ozone levels from 2007-2009. Data recorded atWestern Nevada County air quality monitoring sites indicatesthat air quality in Western Nevada County still exceeds the standard but qualifies forthe extension as illustrated byTable 1 in the enclosure. This request is based upon the area's 2009 fourth highest daily 8-hour ozone concentration.

The 8-hour ozone implementation rule gives U.S. EPAthe discretion to grant up to two one-year extensions ofthe attainmentdate upon application bya state if: 1) the state has complied with all requirements and commitments pertaining tothe area in the

The energy challenge facing California is real. Every Californian needs to take Immediate action to reduce energyconsumption. Fora listofsimple ways you can reduce demandandcutyour energycosts, see ourwebsite.' httpllwww.arb cagov. California Environmental Protection Agency

Printed on Recycled PaperMr. Jared Blumenfeld May 24,2010 Page 2

applicable State Implementation Plan; and 2) airquality data show thatfor the first one-year extension, the area's fourth highestdaily 8-hour average in the attainment year is 0.084 parts per million (ppm) or less. To qualifyfor a second one-year extension, the area's fourth highest daily 8-hourvalue averaged overthe original attainmentyear and the first extension year must be 0.084 ppm or less.

On February 8, 2008, ARB submitted a Reasonably Available Control Technology State Implementation Plan (RACT SIP) forWestern Nevada Countyfor Control Technology Guidelines (CTGs) up through 2005. On August 18, 2008, ARB submitted a RACT SIP forWestern Nevada County for CTGs for 2006 and 2007. We believe with these RACT submissions that Western Nevada County has met, or surpassed, the first requirement to qualifyfor a one-year extension. Table 1, in the enclosure, demonstratesthat Western Nevada County's fourth highest 8-hour ozone averagefor 2009 is belowthe standard, satisfying the second requirement to qualify for a one-year extension.

We believethat Western Nevada County has met both ofthe criteria for thefirst one-year extension oftheir 8-hour ozone attainmentdate and it is appropriatefor U.S. EPAto grant such. We look forward to U.S. EPA approval ofthis requestfor an extension ofthe attainment date. If you have any questions, please call Ms. Lynn Terry, Deput Executive Officer, at (916) 322-2739, or have your staffcontact Ms. Karen Ma no, Chief, Air Quality Data Branch at (916) 322-7137.
/

Enclosure

cc: See next page.Mr. Jared Blumenfeld May 24,2010 Page 3

cc: Ms. Deborah Jordan, Director United States Environmental Protection Agency Air Division-Region 9 75 Hawthorne Street San Francisco, California 94105

Ms. Gretchen Bennitt Air Pollution Control Officer Northern Sierra Air Quality Management District P.O. Box 2509 200 Litton Drive, Suite 320 Grass Valley, California 95945-2509

Ms. Lynn Terry Deputy Executive Officer

Ms. Karen Magliano, Chief Air Quality Data Branch Planning and Technical Support DivisionTable 1 

### Fourth Highest8-hour Ozone Daily Maximums for 2006 to 2009 and 2009 Design Value for Western Nevada County (parts per million)

Fourth-Highest8-hour Ozone Monitoring Site Concentration Design Value 2006 2007 2008 2009 2009 Grass Valley-Litton Building 0.096 0.088 0.091 0.083 0.087
White Cloud

Mountain 0.089 0.082 0.091 0.077 0.083