A diking, drainage, or sewerage improvement district, flood control district, diking district, drainage district, intercounty diking and drainage district, or zone may convey title to any property improvements or assets of the districts or zone to the county or a zone for flood control purposes. If the property improvements or assets are surplus to the needs of the district or zone the transfer may be made by private negotiations, but in all other cases the transfers are subject to the approval of a majority of the registered voters within the district or zone. Nothing in this section permits any district or zone to impair the obligations of any debt or contract of the district or zone.