Cal. Gov. Code § 56889

If any commission order approving or conditionally approving a change of organization or reorganization would result in the annexation to a city of land that is subject to a contract executed pursuant to the Williamson Act (Chapter 7 (commencing with Section 51200) of Division 1), for which the commission has determined pursuant to Section 56754 that the city shall succeed to the contract, the commission shall impose a condition that requires the city to adopt the rules and procedures required by the Williamson Act, including but not limited to the rules and procedures required by Sections 51231, 51237, and 51237.5.