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California Environmental Protection Agency 

# Air Resources Board

Alan C. Lloyd, Ph.D. Chairman 1001 I Street • P.O. Box 2815 • Sacramento, California 95812 • www.arb.ca.gov Gray Davis Governor

July 15, 2003

Mr. Jack Broadbent, Director Air Division - Region IX U.S. Environmental Protection Agency 75 Hawthorne Street San Francisco, California 94105

Dear Mr. Broadbent:

We are transmitting California’s eight-hour ozone monitoring data for 2000 through 2002 to support the U.S. Environmental Protection Agency’s (U.S. EPA) steps to designate areas as attainment or nonattainment for the federal eight-hour ozone standard.

This information updates California’s March 2000 recommendations on designations and boundaries due to changes in air quality status during the monitoring period. Three areas now attain the eight-hour standard (San Francisco Bay Area, Shasta County, and Tehama County) and one additional area now violates the standard (Butte County). Enclosure 1 shows that fourteen areas in California currently violate the standard based on 2000–02 monitoring data. Eleven of these areas are already nonattainment or maintenance for the federal one-hour ozone standard. The remaining rural areas are impacted by transport from upwind urban regions and will be brought into the federal planning process for the first time.

California has widespread ozone pollution resulting from both local sources and winds that blow emissions from urban coastal areas, through the Central Valley, into the Sierra Nevada foothills, and across the eastern desert. There are numerous routes of pollutant transport between the fourteen areas that violate the standard, as well as the San Francisco Bay Area. Thus, the State Implementation Plans (SIP) to attain the eight-hour ozone standard must and will include emission reductions from the contributing upwind districts.

We are in the process of working with the Bay Area Air Quality Management District and its downwind neighbors on a legally enforceable mechanism for addressing this issue. We believe State law provides a sound legal foundation for incorporating upwind emission reductions in downwind area SIPs.Mr. Jack Broadbent, Director

July 15, 2003 Page 2

The federal Clean Air Act generally delegates responsibility to each state to ensure that the comprehensive SIP reduces air pollution to attainment levels for all areas inside its borders. This responsibility encompasses pollution generated in upwind regions that contributes to nonattainment in downwind regions within the same state. California law goes further and clearly imposes an obligation on upwind air districts to mitigate air pollutant transport. ARB is responsible for ensuring this mitigation happens under both federal and State law. Recent revisions to state transport mitigation regulations compel an upwind district to take expeditious action to reduce emissions until the downwind area attains California’s health-protective ozone standard. The requirements on upwind districts also include the adoption of all feasible measures and parity with the downwind area’s program to address new and modified stationary sources. ARB is committed to ensuring effective implementation of these requirements and to reflecting the resulting benefits in the SIPs for downwind areas. Air Resources Board Members and staff are currently working with local air district representatives to craft an effective inter-regional planning strategy for California’s eight-hour ozone SIPs.

Our prior recommendations for nonattainment areas considered air basin boundaries, geography and meteorology, the location of emission sources, transportation corridors, metropolitan areas, and existing political jurisdictions. We will transmit specific descriptions of the recommended nonattainment area boundaries in supplemental correspondence, before U.S. EPA proposes nationwide designations this fall. An outstanding issue is the Sacramento Region boundary, specifically treatment of Southern Sutter County that is now part of the one-hour ozone nonattainment area.

Enclosure 2 provides summary eight-hour ozone data for all California monitoring sites from 2000 through 2002. We will update the air quality data and any changes to our recommendations, based on monitoring during the 2003 ozone season and consideration of the implementation policy, before U.S. EPA finalizes the designations.

If you have any questions, please call Ms. Lynn Terry, Deputy Executive Officer, at (916) 322-2739 or have your staff contact Ms. Cynthia Marvin, Chief, Air Quality and Transportation Planning Branch, at (916) 322-7236.

Sincerely,

Catherine Witherspoon Executive Officer

Enclosures cc: See next page.Mr. Jack Broadbent, Director

July 15, 2003 Page 3

cc: (With Enclosures 1 and 2)

Air Pollution Control Officers

Directors of Metropolitan Planning Organizations

Mr. Brian Smith, Deputy Director Planning and Modal Programs California Department of Transportation 1120 N Street Sacramento, California 95812

Ms. Lynn Terry Air Resources Board

Ms. Cynthia Marvin Air Resources BoardEnclosure 1

Areas in California that Violate the Federal Eight-Hour Ozone Standard

(based on 2000 – 2002 air quality data)

Area Design Value1

(ppm) Includes

South Coast Air Basin 0.128 Western Los Angeles (including Catalina and San Clemente Islands), Orange, Southwestern San Bernardino, and Western Riverside Counties San Joaquin Valley 0.115 San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare, and Western Kern Counties Sacramento Region 0.106 Sacramento, Yolo, Eastern Solano, western portions of El Dorado and Placer County (inclusion of Southern Sutter County to be determined) Western Mojave Desert 0.106 Central San Bernardino County Coachella Valley 0.105 Central Riverside County Ventura County 0.097 Continental portion of Ventura County (excludes Anacapa and San Nicolas Islands) Eastern Kern County 0.095 Portion of Kern County east of the Tehachapi Mountains except the Indian Wells Valley San Diego County 0.095 San Diego County Antelope Valley 0.091 2 Northeastern Los Angeles County Imperial County 0.090 Imperial County Western Nevada County 0.098 Portion of Nevada County west of the crest of the Sierra Nevada Central Mountain Counties 0.092 Amador and Calaveras Counties

Southern Mountain Counties 0.091 Tuolumne and Mariposa Counties

Butte County 0.089 Butte County

1The design value is the three-year average of the annual fourth highest eight-hour ozone concentration at the highest monitor (if less than 0.085 = attainment, if 0.085 ppm or greater = nonattainment) 2Preliminary design value is based on air quality data from 1999 – 2001. Since the monitor was moved in 2001, a final design value cannot be calculated until complete data for the 2003 ozone season are available.

July 15, 2003