California Code, Elections Code - ELEC § 21626

(a) The term of office of any council member who has been elected and whose term of office has not expired shall not be affected by any change in the boundaries of the district from which the council member was elected.

(b) At the first election for council members in each city following adoption of the boundaries of council districts, excluding a special election to fill a vacancy or a recall election, a council member shall be elected for each district under the new district plan that has the same district number as a district whose incumbent's term is due to expire.This subdivision does not apply when a city transitions from at-large to district-based elections.

(c) For a city employing both a primary and a general election, a change in the boundaries of a council district shall not be made between the direct primary election and the general election.

(d) Except as provided in subdivision (a), a person is not eligible to hold office as a member of a city council unless that person meets the requirements of Section 201 of the Elections Code and Section 34882 of the Government Code.