California Code, Government Code - GOV § 58906

If the principal act requires notice to be mailed by first-class mail to all owners of property described in the proposal, including the owners of state assessed property, notice shall be mailed in the form and manner, and at the time, required by such act. If the principal act does not require such notice, the clerk shall cause a notice of the filing or other submission of the proposal to be mailed by post card or first class mail, postage prepaid, to every owner of real property described in the proposal who has filed the statement authorized by the preceding section, at the address shown on such statement, at least 10 days prior to the first hearing or initial action on the proposal. The clerk of the supervising authority may, upon completion of the mailing of such notices, file an affidavit with the supervising authority stating that notices have been mailed to all property owners entitled thereto under the provisions of this chapter. The affidavit of the clerk shall be conclusive evidence as to the mailing or nonmailing of any notice. Mailing of notice to all property owners who have filed a request therefor with the county assessor, as authorized by Section 58905, shall be deemed sufficient compliance with this chapter for all purposes.