Cal. Pub. Resources Code § 5802
Except as provided in Section 5803, all sales by a public entity of land described in Section 5801 shall first be approved by ordinance which shall state that it is subject to the provisions for referendum applicable to such public entity.
Any ordinance subject to referendum under this section shall be published after adoption as required by law for ordinances of the public entity generally, or, if there be no such requirement applicable to such ordinance, then once, pursuant to the provisions of Section 6040 to 6044, inclusive, of the Government Code, within 15 days after the adoption of such ordinance.
Any petition protesting the adoption of the ordinance shall be filed with the public entity within 30 days from the date of final passage of the ordinance.
Ca. Pub. Res. Code § 5802