California Code, Education Code - EDC § 15145

(a) The board of supervisors by an order entered upon its minutes shall prescribe the form of the bonds. The bonds shall be signed by the chairperson of the board of supervisors, or by any other member thereof as the board of supervisors shall, by resolution adopted by a four-fifths vote of all its members, authorize and designate for that purpose, and also signed by the treasurer of the county, and shall be countersigned by the clerk of the board of supervisors or by a deputy of either of the officers. Unless the board of supervisors otherwise provides, all the signatures and countersignatures may be printed, lithographed, engraved, or otherwise mechanically reproduced except that one of the signatures or countersignatures to the bonds shall be manually affixed. Any signature may be affixed in accordance with the provisions of the Uniform Facsimile Signatures of Public Officials Act, Chapter 6 (commencing with Section 5500) of Title 1 of the Government Code. All expense incurred for the preparation, sale, and delivery of the school bonds, including but not limited to, fees of an independent financial consultant, the publication of the official notice of sale of the bonds, the preparation, printing and distribution of the official statement, the obtaining of a rating, the purchase of insurance insuring the prompt payment of interest and principal, the preparation of the certified copy of the transcript for the successful bidder, the printing of the bonds, and legal fees of independent bond counsel retained by the school district or community college district issuing the bonds are legal charges against the funds of the district issuing the bonds and may be paid from the proceeds of sale of the bonds.

(b) Notwithstanding subdivision (a), the board of supervisors may, in its discretion, determine that all of the required signatures and countersignatures shall be by facsimiles, provided, however, that the bonds shall not be valid or become obligatory for any purpose until manually signed by an authenticating agent duly appointed by the board or its authorized designee.