Cal. Water Code § 14034

There shall be collected each year and in the same manner and at the same time as other state revenue is collected, in addition to the ordinary revenues of the state, a sum in an amount required to pay the principal of, and interest on, the bonds maturing each year, and it is hereby made the duty of all officers charged by law with any duty in regard to the collection of the revenue, to do and perform each and every act which shall be necessary to collect the additional sum.