Neb. Rev. Stat. §§ 31-450
In all districts hereafter organized, the board of directors, having first adopted detailed plans and specifications of the work proposed to be done, having made an estimate of the total cost of such contemplated improvement, and having filed such plans, specifications, and estimated cost with the clerk of the county having the largest area of land, shall then publish a notice once each week for three consecutive weeks in a newspaper in each county of an election to vote on the question of proceeding with such work and incurring the necessary liability in all cases in which the estimate of the contemplated work equals seven percent of the taxable value of the lands assessed for such improvement. The election shall be held in all respects as other elections provided for in sections 31-401 to 31-450. If a majority of the votes cast at such election are in favor of proceeding with the work and incurring the necessary liability, then the board, in proceeding therein, shall not incur indebtedness in a total sum in excess of the estimated cost so filed and published. No changes in such plans and specifications shall be made thereafter by the board which cost in the aggregate more than fifteen percent above such estimated cost. If a majority of the votes at such election vote against proceeding and incurring the liability, then the board shall abandon the work and shall thereupon certify to the county clerks a tax levy on all the tracts in the district by valuation sufficient to pay all the liabilities of the district, and the levy shall be entered and collected as other general taxes and used to pay the liabilities.
Neb. Rev. Stat. §§ 31-450