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Adequacy Status of the Maricopa County, Arizona Submitted PM-10 Attainment Plan for Transportation Conformity Purposes

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Environmental Protection Agency (EPA).


Notice of adequacy determination.


In this document, EPA is notifying the public that we have found that submitted Maricopa County (Phoenix, Arizona) serious area particulate matter (PM-10) attainment plan is adequate for transportation conformity purposes. As a result of our finding, the Maricopa Association of Governments and the Federal Highway Administration must use the PM-10 motor vehicle emissions budget from the submitted plan for future conformity determinations.


This determination is effective April 21, 2000.

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The finding is available at EPA's conformity website:​oms/​traq, (once there, click on the “Conformity” button, then look for “Adequacy Review of SIP Submissions for Conformity”). You may also contact Karina O'Connor, U.S. EPA, Region IX, Air Division (AIR-2), 75 Hawthorne Street, San Francisco, CA 94105; (415) 744-1247 or

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This notice announces our finding that the Revised MAG 1999 Serious Area Particulate Plan for PM-10 for the Maricopa County Nonattainment Area (February 2000), submitted by the Arizona on February 16,2000, is adequate for transportation conformity purposes. EPA Region IX made this finding in a letter to the Arizona Department of Environmental Quality and the Maricopa Association of Governments on March 29, 2000. We are also announcing this finding on our conformity website:​oms/​transp/​conform/​pastsips.htm.

Transportation conformity is required by section 176(c) of the Clean Air Act. Our conformity rule requires that transportation plans, programs, and projects conform to state air quality implementation plans (SIPs) and establishes the criteria and procedures for determining whether or not they do. Conformity to a SIP means that transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the national ambient air quality standards.

The criteria by which we determine whether a SIP's motor vehicle emission budgets are adequate for conformity purposes are outlined in 40 CFR 93.118(e)(4). One of these criterion is that the plan provide for attainment of the relevant ambient air quality standard by the applicable Clean Air Act attainment date. We have preliminarily determined that the Maricopa County PM-10 plan does provide for attainment of the PM-10 standards and therefore, can be found adequate.

This adequacy finding is separate from and does not affect our February 25, 2000 finding that the plan is complete under section 110(k)(1) of the Clean Air Act.

We have described our process for determining the adequacy of submitted SIP budgets in guidance (May 14, 1999 memo titled “Conformity Guidance on Implementation of March 2, 1999 Conformity Court Decision”). We followed this guidance in making our inadequacy determination on the Maricopa County PM-10 plan.

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Authority: 42 U.S.C. 7401-7671q.

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Dated: March 30, 2000.

Laura Yoshii,

Acting Regional Administrator, Region IX.

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[FR Doc. 00-8539 Filed 4-5-00; 8:45 am]