Water Code § 71957

The bonds shall be dated, numbered consecutively, signed by the president and treasurer of the district, countersigned by the secretary, and the official seal of the district attached. The interest coupons of the bonds shall be signed by the treasurer of the district. All such signatures and countersignatures may be printed, lithographed, or mechanically reproduced, except that one of the signatures or countersignatures to the bonds shall be manually affixed.