California Code, Elections Code - ELEC § 17601

(a) The following provisions shall apply to those elections where candidates for one or more of the following offices are voted upon: President, Vice President, United States Senator, and United States Representative.

(b) The following data shall be kept by the elections official, on electronic media, stored and unaltered, for 22 months from the date of the election:

(c) If a contest is not commenced within the 22-month period, or if a criminal prosecution involving fraudulent use, using the ballot tally system to mark or falsify ballots, or manipulation of the ballot tally system, is not commenced within the 22-month period, either of which may involve the vote count of the precinct from which voted ballots were received, the elections official shall have the backups destroyed.