California Code, Public Resources Code - PRC § 29430

(a) Any person who owns land within the marsh that is being used for the purpose of agriculture or wildlife habitat on January 1, 1978, or that is used for such a purpose at any time after that date, may petition the local government having jurisdiction over the land to enter into a contract pursuant to the California Land Conservation Act of 1965 (Williamson Act) (Chapter 7 (commencing with Section 51200) of Part 1 of Division 1 of Title 5 of the Government Code) or a wildlife habitat contract, as defined in subdivision (f) of Section 421 of the Revenue and Taxation Code.

(b) Upon receipt of a petition pursuant to subdivision (a), such local government is authorized to, and shall, enter into such contract with the petitioning landowner.