Iowa Code § 468.394
If the proposed improvement is the maintenance of a levee, the amount collected in any one year shall not exceed three dollars and thirty-seven and one-half cents per thousand dollars of the assessment valuation, which said assessment shall be levied at a level rate on the assessable value of the said lands, improvements, easements, and railroads within the district. If the amount necessary to pay for the improvement exceeds said sum, it shall be levied and collected in annual installments of twenty or less. For all other improvements, the board shall levy a rate sufficient to pay for the same, and may, at their discretion, make the same payable in annual installments of twenty or less.
Iowa Code § 468.394
89 Acts, ch 126, §2
Referred to in §468.395, 468.396