Iowa Code § 468.163
Payment to the county treasurer for such certificate shall be from the fund of said drainage or levee district, or subdistrict, on a warrant issued against that fund which shall have precedence over all other outstanding warrants drawn against that fund in the order of their payment. Should there not be a sufficient amount in the fund of said district, or subdistrict, to pay said warrant then the board of supervisors, or the trustees of the district, as the case may be, are authorized to borrow a sum of money sufficient for that purpose on a warrant for that amount on the fund of the district, or subdistrict, which warrant shall bear interest from date at a rate not exceeding that permitted by chapter 74A and shall have preference in payment over all other unpaid warrants on said fund, and the county treasurer shall so enter the same on the list of warrants in the treasurer's office and call the same for payment as soon as there is sufficient money in said fund.
Iowa Code § 468.163
89 Acts, ch 126, §2 97 Acts, ch 121, §29