The district board may hold at any time or, upon petition of any affected landowner or political subdivision which has been assessed after a project has been in existence for at least one year, shall hold a hearing for the purpose of determining the benefits of the project to each tract of land affected. At least ten days’ notice of the hearing must be given by publication in the newspaper or newspapers having general circulation in the district and in the official county newspaper of each county in which the benefited lands are located and by mailing notice by ordinary mail to each owner of land whose assessment is proposed to be raised as determined by the records of the recorder or county treasurer. The provisions of this chapter governing the original determination of benefits and assessment of costs apply to any reassessment of benefits carried out under this section. The board may not be forced to make a reassessment more than once every ten years. Any assessment or balance of an assessment supporting a project fund may not be reduced or impaired by reassessment or otherwise so long as bonds payable out of such fund remain unpaid and moneys are not available in such fund to pay all such bonds in full, with interest. Costs of maintenance must be prorated in accordance with any plan for reassessment of benefits that has been adopted.