Iowa Code § 468.323: Request for relinquishment.

When a county board of supervisors elects to transfer control of a drainage district to a city, as provided in section 468.322, the resolution effecting the transfer shall state a time not less than thirty nor more than ninety days after adoption of the resolution when the transfer of control shall take effect. The resolution shall be certified to the governing body of the city and a copy thereof filed by the county auditor, who shall spread the same upon the records of the drainage district.