Iowa Code § 358.32

The board of supervisors of the county in which the sanitary district or a major portion of it is located shall have jurisdiction of the proceedings on the petition, and the decision of a majority of the members of the board shall be necessary for approval of the petition for conveyance and discontinuance. Orders of the board made under this section shall be spread upon the records of the proceedings of the board of supervisors, and shall be filed with the county recorder but need not be published under section 349.16.