Whenever there is filed with the department a petition signed by the governing body of a county, city, or township or by twenty percent or more of the freeholders within the limits of a proposed vector control district, the department shall fix a time and place for a public hearing on such petition. The place of hearing must be convenient and accessible for a majority of the freeholders of the proposed district. Not less than ten days prior to the date of hearing, notice thereof must be published in at least one newspaper of general circulation in the proposed district. Prior to such hearing the department shall make or cause to be made an investigation of the need for the establishment of the proposed vector control district and shall submit his report to the department. If the department finds that it is not feasible, desirable, or practical to establish the proposed district, it shall make an order denying the petition and state therein the reasons for its action. If, however, the department finds the problems of vector control or other reasons make the establishment of the proposed district desirable, proper, and necessary, it shall grant the petition and create such district and establish the boundaries thereof.