Iowa Code § 76.6: Place of payment.

The principal and interest of all public bonds or obligations of a public corporation in this state are payable at the office of the treasurer or public official charged with the duty of making payment, unless the proceedings of the governing body authorizing the issuance of the public bonds or obligations provide that the public bonds or obligations and interest on the public bonds or obligations are payable at one or more banks or trust companies within or without the state of Iowa, or as otherwise provided by chapter 419, or by mail, wire transfer, or similar means.