CAPCOA BACT Clearinghouse Resource Manual

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VII. Federal versus California Control Technology Requirements

        California Health and Safety Code Section 42300 authorizes delegation of stationary source permitting authority from the state to local air pollution control districts. Each district has its own set of definitions and rules. As a result, the definition of BACT and, where used, LAER can vary by district.

        In the federal Clean Air Act Amendments of 1977, federal statutes and regulations applied BACT and LAER requirements separately in the PSD and NSR programs, respectively. Sources needing a permit under the PSD program are subject to BACT as defined by the Code of Federal Regulations. Sources needing a permit under the NSR program are potentially subject to LAER. In many cases, permitting authorities used BACT and LAER definitions out of the 1977 federal Clean Air Act. However, most California districts have adopted NSR and PSD control technology requirements that deviated in many different ways from the federal definitions of control technology requirements. As a result of this deviation, most California districts have NSR control requirements that are referred to as BACT with definitions more akin to LAER.1 Such BACT definitions are sometimes referred to as California BACT.2 In addition, some districts have control technology requirements for PSD that are more stringent that federal BACT. The next section will provide a more detailed analysis of the differences between federal BACT, federal LAER, and control technology requirements used for NSR and PSD in California.

        The determination of BACT or LAER requirements in a specific permitting action involve comparisons with control technology requirements used in other previous permitting actions for similar sources. Since most BACT definitions in the regulations of California APCDs could qualify as having the stringency of LAER, it is important to know whether the applicable district control technology definition corresponds federal BACT or LAER requirements. Therefore, it is important that a person doing BACT or LAER analysis during an NSR or PSD permitting action know both the wording of:

        1. The BACT or LAER definition applicable in the permitting action; and
        2. The BACT or LAER definitions applicable in previous permitting actions of comparable sources used in the analysis.

When this information is needed, one should obtain it either from the CAPCOA BACT Clearinghouse or from the district contact. Section XI has also been provided to give the current as well as some historical BACT and LAER definitions used by California districts.


1. It is interesting to note that some districts were using the term BACT prior to the 1977 federal Clean Air Act Amendments. As a result, it appears that BACT was already an established term. This may explain the why the term LAER was not widely used in California.

2. The term "California BACT" is often used to distinguish BACT as defined at most large California districts from BACT as defined in the federal Clean Air Act and Code Federal of Regulations.


Best Available Control Technology (BACT) Clearinghouse Program