The authority, as soon as practical after its organization, shall prepare a comprehensive plan with respect to a program for a unified or officially coordinated system as a part of a comprehensively planned development of the urban area within its service area. Said program, to the maximum extent feasible, shall provide for the participation of privately owned systems.

In the preparation of a comprehensive plan, an authority shall make careful and comprehensive surveys and studies of the existing conditions and probable future changes of such conditions within its service area. The comprehensive plan shall be made for the general purpose of guiding and accomplishing a coordinated, adjusted and harmonious development of systems within the service area which, in accordance with present and future needs and resources, will best promote the health, safety and general welfare of the inhabitants of the service area, as well as the orderly and economical development and expansion of the service area.

Prior to the adoption of a comprehensive plan, the authority shall submit its tentative plan to the governing bodies of the participating governments and hold a public hearing in the service area on the plan. At least thirty days prior to the date set for hearing, the authority shall publish a notice of the time and place of the hearing as a Class II legal advertisement in compliance with the provisions of article three, chapter fifty-nine of this code, and the publication area for such publication shall be the service area of the authority. After a public hearing has been held, the authority may by resolution adopt the comprehensive plan and may from time to time amend, supplement or change the comprehensive plan in the same manner in which it was adopted.