Cal. Pub. Cont. Code § 20474

The contract shall be executed on behalf of the district by the commission, subject to approval or rejection by the electors of the district, expressed at an election called for the purpose of issuing bonds or authorizing the tax levy for the payment of the contract. If the electors fail to approve the bond issue, or fail to authorize the tax levy, the contract shall be null and void without notice and the commission shall immediately return the bonds to the contractor.