Cal. Health & Saf. Code § 4611.5
At the hearing, the governing body may add territory to the district if the owners of all of the land in the territory which is proposed to be added to the district have requested such addition in writing, or the governing body has first adopted a resolution of intention to do so. The resolution shall describe the boundaries of the territory which is proposed to be added to the district and shall state the time and place to which the hearing will be continued for the purpose of hearing objections to the proposed addition. Not later than 20 days before the time of such continued hearing, a copy of such resolution shall be mailed, postage prepaid, to each person to whom land in the territory which is proposed to be added to the district is assessed, as such owner is shown on the last equalized county assessment roll, at his address as shown upon the roll. A copy of such resolution shall also be mailed to each person who has any interest in any land within such territory whose name and address and a designation of the land in which he is interested is on file in the office of the city clerk. Any error, omission, or mistake in such mailing, or any failure of any person to receive such copy shall not invalidate the proceedings pursuant to this chapter.
At the continued hearing, the governing body shall hear all objections to the proposed addition and may then take action adding to the district all or part of the territory which is described in the resolution of intention.
Ca. Health and Saf. Code § 4611.5