Iowa Code Title XI. Natural Resources [Chs. 455-485] § 468.50. Levy--interest

When the board has finally determined the matter of assessments of benefits and apportionment, the board shall levy the assessments as fixed by it upon the lands within the district, but an assessment on a tract, parcel, or lot within the district which is computed at less than five dollars shall be fixed at the sum of five dollars. All assessments shall be levied at that time as a tax and shall bear interest at a rate determined by the board notwithstanding chapter 74A from that date, payable annually, except as provided as to payments within a specified time.