Cal. Health & Safety Code § 40724

(a) Each district that is designated as a serious federal nonattainment area for an applicable ambient air quality standard for particulate matter as of January 1, 2004, shall adopt, implement, and submit for inclusion in the state implementation plan, a rule or regulation requiring best available control measures (BACM) for sources for which those measures are applicable and best available retrofit control technology (BARCT) to reduce air pollutants from sources for which that technology is applicable for agricultural practices, including, but not limited to, tilling, discing, cultivation, and raising of animals, and for fugitive emissions from those agricultural practices a manner similar to other source categories by the earliest feasible date, but not later than January 1, 2006. The rule or regulation shall also include BACM and BARCT to reduce precursor emissions in a manner commensurate to other source categories that the district show cause or contribute to a violation of an ambient air quality standard. Each district that is subject to this subdivision shall comply with the following schedule with respect to the rule or regulation imposing BACM and BARCT:
1. (1) On or before September 1, 2004, notice and hold at least one public workshop for the purpose of accepting public testimony on the proposed rule or regulation.
2. (2) On or before July 1, 2005, adopt the final rule or regulation at a noticed public hearing.
3. (3) On or before January 1, 2006, commence implementation of the rule or regulation.
(b) Nothing in this section shall delay or otherwise affect any action taken by a district to reduce emissions of air contaminants from agricultural sources, or any other requirements imposed on a district or a source of air pollution pursuant to the federal Clean Air Act (42 U.S.C. Sec. 7401 et seq.).
(c) In adopting a rule or regulation pursuant to this section, a district shall do all of the following:
1. (1) Ensure the size and duration of use of an internal combustion engine subject to BARCT pursuant to this section is commensurate to the size and duration of use of internal combustion engines subject to regulation by a district or the state board regulated at other stationary sources.
2. (2) Ensure that BARCT established pursuant to this section for an internal combustion engine is similar to BARCT for other stationary source engines subject to regulation by a district or the state board.
3. (3) Ensure that the cost-effectiveness of BARCT for an internal combustion engine subject to this section is similar to the cost-effectiveness of BARCT for other internal combustion engines subject to regulation by a district or the state board.
4. (4) Compare the cost-effectiveness of BARCT for an internal combustion engine subject to this section to the list of available and proposed control measures prepared pursuant to Section 40922.
5. (5) Adopt control measures pursuant to this section in order of their cost-effectiveness, unless a district determines that a different order of adoption is necessary due to the enforceability, public acceptability, or technological feasibility of a given control measure, or to expeditiously attain or maintain a national or state ambient air quality standard.
6. (6) Except as otherwise provided under this section, ensure that any rule or regulation adopted pursuant to this section complies with all applicable requirements of this division, including, but not limited to, any applicable requirements established pursuant to Sections 40703, 40727, 40728.5, and 40920.6.
7. (7) Hold at least one public meeting that is conducted at a time and location that the district determines is convenient to the public at which the district reviews the comparison prepared pursuant to paragraph (4).
(d) Nothing in this section limits the authority of a district to regulate a source including, but not limited to, a stationary source that is an agricultural source over which it otherwise has jurisdiction pursuant to this division or the federal Clean Air Act (42 U.S.C. Sec. 7401 et seq.) or any rules or regulations adopted pursuant to that act. Nothing in this section shall delay or otherwise affect any action taken by a district to reduce emissions of air contaminants from agricultural sources, or any other requirements imposed upon a district or a source of air pollution pursuant to the federal Clean Air Act. This section may not be interpreted to delay or otherwise affect the adoption, implementation, or enforcement of any measure that was adopted, or included in a rulemaking calendar or air quality implementation plan that was adopted, by the district prior to January 1, 2004.