ELEC §21606: (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

(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 and that member shall continue to represent the constituents residing in the district boundaries from which the member was elected for the duration of that term of office. This section does not prevent a city council from assigning a city elected official or city official to provide constituent services to residents of an area that is temporarily not represented by a council member due to redistricting. (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) 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.