1. At the hearing the department shall hear all persons affected by the formation of the proposed district. The department may change the tentative boundaries of the proposed district, but in that case a new hearing shall be held thereon after due notice thereof.

2. After the final hearing the department shall determine whether or not the tentative boundaries as described include all the lands which should be included in the district and exclude as far as is reasonably possible all lands which will not be benefited by drainage; whether or not the lands included therein will be made more productive by drainage, the public health, safety or welfare will be benefited thereby and it will be to the public interest to form the drainage improvement district and carry out further proceedings for final fixation of boundaries or whether the application should be rejected. It shall embody such determination and disposition of the case in a written order, which shall be filed and notice of such filing given.

3. If the decision is favorable, such order shall declare the district to be formed and shall direct the making of surveys and the taking of the remainder of the proceedings for final fixation of boundaries for the district all as provided by sections 15-1917 to 15-1927, inclusive. Thereupon the order may be reviewed as provided by section 15-0905, and in due course shall be recorded.

4. The district shall be held to have been formed on the date of such order, but such formation shall not be effective until such order, as made or modified on review, shall have been recorded.