Cal. Pub. Util. Code § 29180

The district may prescribe the form of such bonds, and of the interest coupons attached thereto. Bonds shall be signed by the president of the board (or such other member of the board as the board shall by resolution designate) and countersigned by the secretary of the district and the seal of the district shall be affixed thereto. The interest coupons on said bonds shall be numbered consecutively and signed by the treasurer of said district. The signature on all coupons and one signature on the bonds may be engraved, lithographed, or printed facsimile signature. The seal of the district may be affixed to any bond by mechanical reproduction of a facsimile thereof. In case any officer whose signature or countersignature appearing on the bonds or coupons shall cease to be such officer before the delivery of such bonds to the purchaser, such signature or countersignature shall nevertheless be valid and sufficient for all purposes, the same as if such officer had remained in office until the delivery of the bonds. If the district appoints a registration agent, fiscal agent, or other agent to authenticate bonds, any bond of the district, whether in coupon or registered form, may be signed by the facsimile signatures of the officers of the district with a facsimile seal of the district affixed mechanically or otherwise reproduced thereon, provided that such bonds shall be authenticated by the fiscal agent, registration agent, or other agent appointed by the district for that purpose. Any agent appointed by the district to authenticate registered bonds or exchange bonds of different denominations, or coupon bonds for registered bonds, or vice versa, shall be a bank or trust company authorized to transact, and transacting, business in the State of California or the State of New York.