Iowa Code § 384.88: Sole remedy.

The sole remedy for a breach or default of a term of a revenue bond or pledge order is a proceeding in law or in equity by suit, action or mandamus to enforce and compel performance of the duties required by this subchapter and of the terms of the resolution authorizing the issuance of the revenue bonds or pledge orders, or to obtain the appointment of a receiver to take possession of and operate the city utility, combined utility system, city enterprise, or combined city enterprise, and to perform the duties required by this subchapter and the terms of the resolution authorizing the issuance of the revenue bonds or pledge orders.