Cal. Gov. Code § 59590

If the holders of one or more of the original bonds do not enter any proposal or contract with the legislative body to refund the bonds but the holders of 75 percent or more of the bonds do contract with the legislative body which conducts the proceedings, it may refund all of the bonds pursuant to this chapter. In such event, prior to recording the reassessment, sufficient money to provide adequately for the retirement or payment of the original bonds of the nonconsenting holders shall be set aside in the proper fund for that purpose.