Iowa Code § 357F.14
The owner of any property in an unincorporated area contiguous to the boundaries of an established district may petition the board to be included in the district. Upon receipt of the petition, the board shall submit the request to a competent disinterested civil engineer to investigate the feasibility of adding the additional territory and to make a report to the board. If the board agrees that the property should be added to the district, the tax levy for the next year shall be applied to the property and on the first day of the next fiscal year the property shall become a part of the district. If the district lies in more than one county the joint action of the boards involved is required to add additional territory.
Iowa Code § 357F.14
92 Acts, ch 1226, §15