When the landowners in a proposed subdistrict desire that a subdistrict be organized, they shall file a petition with the board of soil and water conservation district supervisors requesting a hearing and a referendum thereon. The area must be contiguous and shall include the entire hydrologic area on which a proposed plan of work is to be developed. The petition shall set forth a legal description by congressional subdivision, or otherwise, of the land suggested for inclusion in the subdistrict. The petition shall contain a brief statement giving the reason for organization, requesting that the proposed area be organized as a subdistrict and must be signed by one or more owners of fifty percent of the lands in the proposed subdistrict. Land already in one subdistrict cannot be included in another. The supervisors shall review the petition and if found adequate shall arrange for a hearing thereon.