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Summary of Portland Carbon Monoxide (CO) 2nd 10-year Maintenance Plan


The Portland, Oregon, nonattainment area was designated nonattainment for carbon monoxide (CO) and classified as moderate upon enactment of the Clean Air Act Amendments in 1990.

Oregon submitted a CO maintenance plan on August 30, 1996, and EPA announced its proposed approval of the plan (62 FR 31398 (PDF)(8 pp, 155 K, About PDF)). On September 2, 1997, EPA approved the Portland CO Maintenance Plan (62 FR 46208 (PDF)(4 pp, 126 K)).

On November 5, 1999, Oregon submitted a complete rule renumbering and relabeling package to EPA for approval in the SIP. On January 22, 2003, EPA approved the recodified version of Oregon's rules to remove and replace the outdated numbering system (68 FR 2891 (PDF)(19 pp, 205 K)). The following list refers to the currently approved SIP rules.

On December 27, 2004, Oregon submitted a Portland CO 2nd 10-Year maintenance plan to EPA. EPA proposed to approve the 2nd 10-Year maintenance plan on September 6, 2005 (70 FR 52956 (PDF)(5 pp, 156 K)), and finalized the proposal on January 24, 2006 (71 FR 3768 (PDF)(3 pp, 150 K)).


The plan relies on control strategies needed to maintain the National Ambient Air Quality Standards (NAAQS) for carbon monoxide. The second 10-year plan changes the I/M requirement for CO from the current Enhanced I/M program to the Basic I/M program. The Oxygenated Fuel Program remains a control measure in the Portland CO maintenance area until October 31, 2007 when it will be discontinued. It will then become a contingency measure in the second 10-year maintenance plan as required by section 175A(d) of the Clean Air Act. Best Available Control Technology continues to be required. The plan also continues to offer an industrial Growth Allowance that may be used by new or expanding sources instead of securing emission offsets. The Transportation Control Measures in this plan replace the TCMS in the first Portland Area CO Maintenance Plan.


  • OAR 340-200-0040 - State of Oregon Clean Air Act Implementation Plan
  • OAR 340-204-0090 - Oxygenated Gasoline Control Areas
  • OAR 340-224-0060 - Requirements for Sources in Maintenance Areas
  • OAR 340-242-0440 - Industrial Growth Allowance Allocation
  •  40 CFR Part 86 - Federal Motor Vehicle Emission Control Program 
  • CCTMP adopted December 6, 1995

Contingency Measures

Oxygenated fuels reinstated (effective October 31, 2007).

Downtown Portland Parking Local Improvement District (LID):

  • Increased parking pricing in the Central City.
  • Increased funding for transit.
  • Congestion pricing on major regional transportation corridors.
  • A trip reduction program.
  • Regional mandatory parking ratios.
  • Accelerated implementation of bicycle and pedestrian networks.

EPA Effective Date

February 23, 2006