Cal. Gov. Code § 53323
At the hearing, protests against the establishment of the district, the extent of the district, or the furnishing of specified types of public facilities or services within the district may be made orally or in writing by any interested person. Any protests pertaining to the regularity or sufficiency of the proceedings shall be in writing and shall clearly set forth the irregularities and defects to which objection is made. Any written protest not personally presented by the author of that protest at the hearing shall be filed with the clerk of the legislative body at or before the time fixed for the hearing. The legislative body may waive any irregularities in the form or content of any written protest and at the hearing may correct minor defects in the proceedings. Written protests may be withdrawn in writing at any time before the conclusion of the hearing.
Ca. Gov. Code § 53323