California Code, Streets and Highways Code - SHC § 5720

If a county is conducting the proceedings the legislative body may designate the county road commissioner or any other competent county officer, other than the county surveyor, to serve without additional compensation from the county, as the officer to perform any or all of the duties conferred upon the street superintendent or the engineer in this division.  The duties thus transferred shall be the duties of the officer so designated, and all of the provisions of this division relating to such duties and to the incidental expenses thereof shall apply to such officer.