After the hearing has been concluded, and after all the protests and requests have been considered, the governing body may make such changes in the proposed improvements or in the area to be included in the district as it may consider desirable or necessary, providing said changes are not substantial. However, no such changes shall be made without a new costs and feasibility report being prepared, and public hearing held, if the public utilities concerned deem it necessary or such changes are determined to be substantial by the governing body.
The governing body shall, after considering matters brought forth at the hearing, either abandon the district and project or adopt an ordinance establishing the district and authorizing the project. Such ordinance shall be published in the manner provided in subsection (8) of section 50-2509, Idaho Code, but need not be mailed. If an ordinance be adopted establishing the district, such ordinance shall finally and conclusively establish the regular organization of the district against all persons, unless an action attacking the validity of the organization shall be commenced in a court of competent jurisdiction within thirty (30) days after the adoption of such ordinance. Such action shall be subject to the provisions of section 50-2511. Thereafter, any such action shall be perpetually barred and the organization of said district shall not be directly or collaterally questioned in any suit, action, or proceedings.