Cal. Pub. Util. Code § 13106

The provisions of any resolution constituting a part of the proceedings for the issuance of any bonds under this chapter, when so declared by its terms, or by the terms of any other such resolution, shall constitute a contract between the district and the holders of such bonds, and the provisions thereof shall be enforceable by mandamus or any other appropriate suit, action or proceeding at law or in equity in any court of competent jurisdiction.