California Code, Harbors and Navigation Code - HNC § 7121

(a) No ordinance shall become effective until 30 days from and after the date of its passage, except the following:

(b) Prior to the effective date thereof ordinances shall be subject to referendum in the same manner and with the same effect as ordinances of counties under Article 2 (commencing with Section 9140) of Chapter 2 of Division 9 of the Elections Code and terms used therein shall have the meanings set forth in Section 7120.