Neb. Rev. Stat. §§ 31-426
The board of directors shall employ such engineer, surveyor, and other help, as it may deem necessary and proper, and shall proceed according to its best judgment to carry out such work of the character provided for by sections 31-401 to 31-450 as it deems advisable for the public health, convenience and welfare. The board of directors shall in its discretion, from time to time, determine whether the necessary work shall be done by hiring by the day, or by contract. Before any contract shall be let, estimates of the cost thereof shall be made, and the contract price shall not exceed the estimate. No officer or director shall be in any way interested in any such contract, and any such contract shall be void if any officer or director is interested therein, and no recovery shall be had thereon; Provided, however, that nothing in this section shall be construed to prevent the board of directors from hiring one of its members by the day to superintend maintenance work within the district. The board of directors shall likewise, when in its judgment it is for the best interest of the district, be empowered to purchase all necessary machinery and equipment for the purpose of maintaining, cleaning out or reconstructing existing ditches, or for the purpose of constructing new ditches within the district, and for such work may hire by the day, week or month, all necessary help.
Neb. Rev. Stat. §§ 31-426