Neb. Rev. Stat. §§ 31-332
If for any reason the cost of the drainage works and improvements exceeds the amount of the tax levied against the lands and property as above set out, the board of supervisors may levy such other and further installments as may be necessary to complete the works and improvements, but the total amount of all such levies and installments shall in no event exceed the total amount of benefits assessed to the lands and property in the district, and such additional cost shall be apportioned to the lots, tracts, lands and property in the same proportion as in the first apportionment; Provided, the board of supervisors shall first give notice thereof by causing a publication to be made once a week for two consecutive weeks in some newspaper published in each county in the district, the last publication to be at least ten days before the day set for hearing. The board of supervisors may correct erroneous assessments and grant relief therefrom, and may correct clerical or other manifest errors in the schedules of the apportionment of the cost discovered after certification to the county clerk.
Neb. Rev. Stat. §§ 31-332