At the hearing, if the board of directors of such district deems it not for the best interest of such district that a change of its boundaries be so made as to include therein the lands mentioned in the petition, the board of directors of such district shall order that the petition be rejected. But if the board of directors of such district deems it for the best interest of such district that the boundaries of such district be changed and if it appears that the petition for the annexation and incorporation of the tract or tracts of land has been signed and presented as provided in section 46-574, that the allegations of the petition are true, and that no protesting petition has been filed, or if filed has been dismissed as provided by sections 46-574 to 46-584, the board of directors of such district may enter a tentative order annexing and including all lands described in the petition, or some part thereof. The order shall not become final until the proposition of levying taxes as provided for in section 46-543 has been complied with and until the proposition of levying taxes has been submitted by a resolution of the board of directors of such district to the qualified electors residing within the tract or tracts of land described in the tentative order at an election held for that purpose in the same manner as provided for submission of incurring bonded indebtedness in sections 46-564 to 46-566, and when the proposition has been approved by a majority of the qualified electors residing within the tract or tracts of land voting on the proposition at such election, then the board of directors shall enter a final order annexing and including all lands described in the tentative order. If at such election a majority of the qualified electors vote against the proposition, then the board of directors of such district shall set aside the tentative order, shall order that the petition be denied, and shall proceed no further in that matter. If the proposition is approved by a majority of the qualified electors of the tract or tracts voting on the proposition at such election in the manner provided for in section 46-543, the board of directors of such district shall certify to the county board of the county in which the tract or tracts of land are situated the rate of tax to be levied. The final order entered by the board of directors of such district shall describe the entire boundaries of the district, and for that purpose the board of directors may cause a survey of such portions thereof to be made as the board of directors deems necessary. A copy of the final order of the board of directors ordering such annexation, certified by the president and secretary of the board of directors of such district, shall be filed with the Department of Natural Resources, and thereupon the district shall be and remain a reclamation district as fully and to every intent and purpose as if the lands which are included in the district by the annexation thereof and the change of boundaries had been included therein at the original organization of the district. Such tract or tracts of land so annexed to such district shall enjoy all the rights and privileges, of whatever kind and nature, and be subject to all the contract, obligation, lien, or charge for or upon which the original district was or might become liable or chargeable.