Cal. Education Code § 5441

The returns of any school district or community college district election received by the county elections official having jurisdiction shall, after the date of the declaration and certification of the final results of the election, be disposed of as follows: (a) The sealed envelope containing the voted ballots, including ballots rejected for improper markings, shall be kept by the county superintendent unopened and unaltered for six months. If a contest or criminal prosecution is not commenced within the six-months’ period as provided in Division 16 (commencing with Section 16000) of the Elections Code, he or she shall destroy the envelope, or have it destroyed, without its being opened or its contents examined. This paragraph also applies to absent ballots and identification envelopes. (b) The envelope containing spoiled, canceled, and defaced unused ballots shall remain unopened in the custody of the county superintendent and shall be held and disposed of as is the envelope provided for in paragraph (a) of this section. (c) The envelope containing the tally sheet, challenge sheet, challenge list, assisted voter list, and affidavits of election officers assisting voters, shall be disposed of in the same manner, but the contents of this envelope may be made available to voters for inspection at any time following commencement of the official canvass of votes.