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  2. Air Quality Implementation Plans

Voluntary Incentive Measures in the California SIP

South Coast Incentive Measure

Related Content: Approved Air Quality Implementation Plans in EPA's Pacific Southwest (Region 9)

On January 15, 2021, EPA approved the California Air Resources Board's (CARB) Resolution #18-3, as amended by Executive Order S-20-030 (“South Coast Incentive Measure”), into the California State Implementation Plan (SIP) pursuant to section 110 of the Clean Air Act (CAA) (86 FR 3820, Jan 15, 2021). The South Coast Incentive Measure contains commitments by the State to:

  • monitor and report on the South Coast Air Quality Management District’s (SCAQMD) implementation of 1,300 on-road heavy-duty diesel truck repower and replacement projects during the 2019-2022 timeframe under the Carl Moyer Memorial Air Quality Standards Attainment Program;
  • achieve 1 ton per day (tpd) of NOx emission reductions in the South Coast Air Basin by December 31, 2022, through implementation of these incentive projects or appropriate substitute measures;
  • submit an annual demonstration report to EPA (beginning in March 2020 until 2023) that contains specific information about projects funded through the previous year; and
  • submit substitute measures if EPA determines by July 1, 2021 that the identified incentive projects are insufficient to achieve the 1 tpd NOx tonnage commitment (referred to as an "insufficiency finding").

More information on EPA's approval of the South Coast Incentive Measure into the California SIP can be found on Regulations.gov.

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  • EPA Insufficiency Finding for South Coast Incentive Measure (pdf) (240.73 KB, June 30, 2021)
    On June 30, 2021, EPA determined that information submitted by the California Air Resources Board (CARB) is insufficient to demonstrate that Carl Moyer on-road heavy-duty diesel truck replacement and repower projects implemented pursuant to the South Coast Incentive Measure will achieve 1 ton per day (tpd) of NOx reductions in the South Coast Air Basin by December 31, 2022.

Air Quality Implementation Plans

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Last updated on April 28, 2025
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