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Adequacy Status of the Idaho, Northern Ada County PM10

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Environmental Protection Agency (EPA).


Notice of adequacy determination.


In this notice, the EPA is notifying the public of its finding that the motor vehicle emissions budgets (MVEBs) for particulate matter with an aerodynamic diameter of a nominal 10 microns or less (PM10), nitrogen oxides (NOx), and volatile organic compounds (VOC) for the years 2008, 2015 and 2023 in the Northern Ada County PM10 State Implementation Plan, Maintenance Plan: Ten-Year Update (Maintenance Plan Update) are adequate for transportation conformity purposes. The Maintenance Plan Update was submitted to the EPA by the State of Idaho Department of Environmental Quality (IDEQ or the State) on March 11, 2013, with a clarification to the MVEB submitted on April 16, 2013. As a result of this finding, the Community Planning Association of Southwest Idaho, the Idaho Transportation Department and the U.S. Department of Transportation will be required to use these MVEBs for future transportation conformity determinations.


This finding is effective June 21, 2013.

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The finding will be available at the EPA's conformity Web site:​otaq/​stateresources/​transconf/​adequacy.htm. You may also contact Claudia Vergnani Vaupel, U.S. EPA, Region 10 (OAWT-107), 1200 Sixth Ave., Suite 900, Seattle WA 98101; (206) 553-6121 or

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This action provides notice of the EPA's adequacy finding regarding the MVEBs in the Maintenance Plan Update in Northern Ada County. The EPA's finding was made pursuant to the adequacy review process for implementation plan submissions delineated at 40 CFR 93.118(f)(1) under which the EPA reviews the adequacy of an implementation plan submission prior to the EPA's final action on the implementation plan.

The IDEQ submitted the Maintenance Plan Update to the EPA on March 11, 2013, with a clarification to the MVEBs submitted on April 16, 2013. Pursuant to 40 CFR 93.118 (f)(1), the EPA notified the public of its receipt of this plan that would be reviewed for an adequacy determination on the EPA's Web site and requested public comment by no later than May 15, 2013. The EPA received no comments on the plan during that comment period. As part of our review, we also reviewed comments submitted to the IDEQ during the State's public hearing process and the State's response to those comments. One comment related to the MVEBs was submitted during the State's public hearing process. The commenter requested an explanation of the differences in the State's current and previous PM10 emission budgets, and a justification for the State's reliance on an emission factor that differed from the factor previously relied-upon in the State's emission budget. The EPA finds that the State addressed the discrepancy identified by the commenter and adequately explained the derivation of the State's current PM10 emission budget.

The EPA Region 10 sent a letter to the IDEQ on May 17, 2013 (adequacy letter), subsequent to the close of the EPA comment period, stating that the EPA found the new MVEBs in the submitted Maintenance Plan Update to be adequate for use in transportation conformity. A copy of the adequacy letter and its enclosure is available at the EPA's conformity Web site:​otaq/​stateresources/​transconf/​adequacy.htm. The new MVEBs that the EPA determined to be adequate for purposes of transportation conformity are listed in the following table.

MVEBs for Northern Ada County PM10 Maintenance Area

[tons per day]

Budget yearPM10NOXVOC

Transportation conformity is required by section 176(c) of the Clean Air Act. The EPA's conformity rule requires transportation plans, programs, and projects to conform to state 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 minimum criteria by which we determine whether a SIP's MVEBs are adequate for conformity purposes are specified at 40 CFR 93.118(e)(4). The EPA's analysis of how the State's submission satisfies these criteria is found in the adequacy letter. The EPA's MVEB adequacy review is separate from the EPA's SIP completeness review and it also should not be used to prejudge the EPA's ultimate approval of the SIP. Even if we find the budget adequate, the SIP could later be disapproved.

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

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Dated: May 23, 2013.

Dennis J. McLerran,

Regional Administrator, Region 10.

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[FR Doc. 2013-13449 Filed 6-5-13; 8:45 am]