California Code, Health and Safety Code - HSC § 9528

In any city where there is no department or officer charged with or designated for the enforcement of this part, the appropriate department, officer or officers of the county in which such city is located shall enforce this part.

In any county where there is no department or officer charged with or designated for the enforcement of this part, this part shall be enforced by the county engineer, if there is a county engineer, and if not, then by the county surveyor.