Iowa Code § 468.362
At the time fixed, the board shall determine the advisability of such division and shall make such order with reference thereto as shall be deemed proper, having consideration for the interests of all concerned. If such division is made, the board or boards having jurisdiction of the original district shall retain jurisdiction of the new districts created by such division for the purpose of collecting assessments theretofore made and making such additional assessments as are necessary to pay the obligations theretofore contracted. For all other purposes, each division shall be under the jurisdiction of the board or boards of supervisors which would have had jurisdiction thereof if originally established as an independent district.
Iowa Code § 468.362