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Adequacy Determination for the Denver Metro Area and North Front Range 8-Hour Ozone Attainment Plan's Motor Vehicle Emissions Budgets for Transportation Conformity Purposes; State of Colorado

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Environmental Protection Agency (EPA).


Notice of adequacy.


In this notice, EPA is notifying the public that the Agency has found that the motor vehicle emissions budgets for nitrogen oxides (NOX) and volatile organic compounds (VOC) contained in the Denver Metro Area and North Front Range 8-Hour Ozone Attainment Plan (hereafter “Denver/NFR Ozone Attainment Plan”) are adequate for transportation conformity purposes. The Denver/NFR Ozone Attainment Plan was submitted to EPA as a revision to the State Implementation Plan (SIP) on June 18, 2009, by James B. Martin, Director, Colorado Department of Public Health and Environment. As a result of our finding, the Denver Regional Council of Governments (DRCOG), the North Front Range Metropolitan Planning Organization (NFR MPO), the Colorado Department of Transportation and the U.S. Department of Transportation are required to use these motor vehicle emissions budgets for future transportation conformity determinations once this finding becomes effective.


This finding is effective March 19, 2010.

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Tim Russ, Air Program (8P-AR), United States Environmental Protection Agency, Region 8, 1595 Wynkoop Street, Denver, Colorado 80202-1129, (303) 312-6479, or

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Throughout this document, whenever “we,” “us,” or “our,” are used, we mean EPA.

This notice is simply an announcement of a finding that we have already made. EPA sent a letter to the Colorado Department of Public Health and Environment (CDPHE) on January 21, 2010, stating that the motor vehicle emissions budgets (MVEB) in the submitted Denver/NFR Ozone Attainment Plan are adequate. The MVEBs in the Denver/NFR Ozone Attainment Plan were posted for adequacy review on EPA's transportation conformity Web site on October 15, 2009. The public comment period closed on November 16, 2009 and we did not receive any comments in response to the adequacy review posting (see​otaq/​stateresources/​transconf/​currsips.htm#denver-me).

The MVEBs we found adequate are presented in the following table:

Area of applicability2010 NOX emissions (tons per day)2010 VOC emissions (tons per day)
Northern Subarea 120.519.5
Southern Subarea 1102.489.7
Total Nonattainment Area122.9109.2
1 The Subareas are defined in section VI of the Denver/NFR Ozone Attainment Plan.

As we stated in our January 21, 2010 letter to CDPHE, the initial conformity determination must be done using the total nonattainment area MVEBs for NOX and VOCs. After the initial conformity determination, DRCOG and the NFR MPO may switch from using the total nonattainment area MVEBs to using the sub-area MVEBs for determining conformity. To switch to use of the sub-area MVEBs (or to subsequently switch back to use of the total nonattainment area MVEBs), DRCOG and the NFR MPO must use the process as described in the Denver/NFR Ozone Attainment Plan on pages VI-4 through VI-6.

Transportation conformity is required by section 176(c) of the Clean Air Act. The conformity rule provisions at 40 CFR part 93 require that transportation plans, programs, and projects conform to SIPs and establish 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 Standard (NAAQS).

The criteria by which we determine whether a SIP's MVEBs are adequate for conformity purposes are outlined in 40 CFR 93.118(e)(4) which was promulgated August 15, 1997 (see 62 FR 43780). We described our process for determining the adequacy of submitted SIP MVEBs in our July 1, 2004 Transportation Conformity Rule Amendments (see 69 FR 40004). We used these resources in making our adequacy determination. Please note that our adequacy review is separate from our rulemaking action on the Denver/NFR Ozone Attainment Plan and should not be used to prejudge our ultimate approval or disapproval of the SIP revision. Even if we find a budget adequate, we may later disapprove the SIP.

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Authority: 42 U.S.C. 7401 et seq.

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Dated: February 19, 2010.

Carol Rushin,

Acting Regional Administrator, Region 8.

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[FR Doc. 2010-4551 Filed 3-3-10; 8:45 am]