Cal. Elec. Code § 4104

(a) At the first general district election conducted by all-mailed ballot the following question shall be printed on the ballot and boxes shall be provided for the voter to indicate “Yes” or “No”:
“SHALL THE MAILED BALLOT BE USED TO CONDUCT ALL FUTURE GENERAL DISTRICT ELECTIONS?”
(b) If the majority of the voters favor the all-mailed ballot election it shall be adopted as the procedure for conducting future general district elections. If the question is rejected by the voters it may be resubmitted at any subsequent general district election in the manner provided for in Section 4105.