Cal. Pub. Cont. Code § 21008

By said contract the county shall undertake that the board of supervisors will, upon the fulfillment and performance of the contract on the part of the contractor, and under the provisions of the Drainage District Improvement Act of 1919 take all steps, in or by said act authorized to be taken, to effect the issuing by the county treasurer of the bonds in said act authorized to be issued, and provide a fund for their payment, as in or by said act prescribed. The contract shall state that in no case shall the county be liable thereunder, nor any officer thereof be beholden thereunder except for the discharge of official duty under the law.