July 14, 2000

Ms. Deborah Jordan
Acting Director
Air Division
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105

Dear Ms. Jordan:

This letter transmits the Air Resources Board's (ARB) recommendations for area designations and nonattainment area boundaries for the new eight-hour ozone National Ambient Air Quality Standard in California. We have enclosed our final staff report entitled "Recommended Area Designations for the Federal Eight-Hour Ozone Standard," which includes the designations and boundaries as approved by our Board on March 23, 2000 and reflected in Resolution 00-10. This final report also reflects more complete ozone data for the 1999 calendar year that became available subsequent to Board action - these data do not change any of the recommended designations.

Our recommended nonattainment area boundaries for the eight-hour ozone standard generally follow existing one-hour ozone federal nonattainment area boundaries, with a few exceptions. These exceptions are based on changes to air basin boundaries, as well as the need to separate some very large areas according to political jurisdiction. This can create a confusing situation, especially for transportation agencies that must analyze conformity for one-hour and eight-hour ozone nonattainment areas. We are requesting that you remedy this situation by updating the one-hour ozone nonattainment area boundaries to match the more current eight-hour ozone boundaries.

I would also like to respond to some of the issues raised by the U.S. Environmental Protection Agency (U.S. EPA) while we were developing our recommendations. These issues include: a mechanism for linking the attainment demonstrations for each nonattainment area to address transport between these areas; the appropriate designation for Sutter County; and the appropriate boundary affecting Joshua Tree National Park.

Linking the Attainment Demonstrations. We have recommended sixteen separate nonattainment areas spanning the State from Shasta County in the north to Imperial County in the south. Given the extensive pollutant transport between these areas, the eight-hour ozone State Implementation Plans (SIPs) will rely on emission reductions from a combination of local, upwind, statewide, and national control measures to demonstrate progress and attainment.

We recognize U.S. EPA's concern that intrastate ozone and ozone precursor transport be properly addressed to ensure that all areas of the State attain the standard. We expect two major ozone field studies in Northern and Southern California to provide the technical basis for two modeling domains in the SIPs. As we have discussed, ARB intends to package the local SIPs for areas within each domain to demonstrate attainment in both upwind and downwind areas. Over the next several months, ARB staff will work with U.S. EPA and local air districts to formalize this approach through a Memorandum of Agreement.

Sutter County. U.S. EPA has concurred with most of ARB's recommendations, but we continue to disagree on the appropriate designation for Sutter Buttes. In this case, a monitor sited atop an isolated mountain to detect pollutant transport aloft measures high levels of ozone. The ozone concentrations aloft are not representative of air quality in the nearby community 2,000 feet below - the community monitor detects no violations. Although we disagree with U.S. EPA's assertion that Sutter Buttes should be designated nonattainment, we appreciate your staff's efforts to find more sensible ways to implement the standard in just the elevated portion of Sutter County.

Joshua Tree National Park. Another area of disagreement is the nonattainment area boundary in the Eastern Desert, which excludes most of the Joshua Tree National Park. We do not believe there is sufficient monitoring data to change the existing boundaries at this time. We plan to initiate special purpose monitoring in the Eastern Desert by next year to determine the extent of ozone pollution in the area. This monitoring will help resolve whether to expand the nonattainment area to include the whole Park or beyond. We will work with U.S. EPA, the air districts, the National Park Service, and other interested stakeholders to define appropriate nonattainment area boundaries. In the meantime, upwind sources in the South Coast Air Basin and Coachella Valley that impact air quality in the Park are already being controlled as part of existing ozone strategies.

We look forward to working with you as you finalize the area boundaries. If you have any questions, please call me at (916) 445-4383 or Ms. Cynthia Marvin, Chief, Air Quality and Transportation Planning Branch, at (916) 322-7236.



Michael P. Kenny
Executive Officer


cc: (with Enclosure)
  All Air Pollution Control Officers
  Mark A. Pisano, Executive Director
Southern California Association of Governments
818 West Seventh Street, 12th Floor
Los Angeles, California 90017-3435
  Stew Wilson, Executive Director
California Air Pollution Control Officers Association
3232 Western Drive
Cameron Park, California 95682-9296

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Area Designations for Federal 8-Hour Ozone Standard

California Environmental Protection Agency

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