Cal. Lab. Code § 1773
The body awarding any contract for public work, or otherwise undertaking any public work, shall obtain the general prevailing rate of per diem wages and the general prevailing rate for holiday and overtime work in the locality in which the public work is to be performed for each craft, classification, or type of worker needed to execute the contract from the Director of Industrial Relations. The holidays upon which those rates shall be paid need not be specified by the awarding body, but shall be all holidays recognized in the applicable collective bargaining agreement. If the prevailing rate is not based on a collectively bargained rate, the holidays upon which the prevailing rate shall be paid shall be as provided in Section 6700 of the Government Code.
In determining the rates, the Director of Industrial Relations shall ascertain and consider the applicable wage rates established by collective bargaining agreements and the rates that may have been predetermined for federal public works, within the locality and in the nearest labor market area. Where the rates do not constitute the rates actually prevailing in the locality, the director shall obtain and consider further data from the labor organizations and employers or employer associations concerned, including the recognized collective bargaining representatives for the particular craft, classification, or type of work involved. The rate fixed for each craft, classification, or type of work shall be not less than the prevailing rate paid in the craft, classification, or type of work.
If the director determines that the rate of prevailing wage for any craft, classification, or type of worker is the rate established by a collective bargaining agreement, the director may adopt that rate by reference as provided for in the collective bargaining agreement and that determination shall be effective for the life of the agreement or until the director determines that another rate should be adopted.
Ca. Lab. Code § 1773