A water resource board may hold at any time or, upon petition of any affected landowner or assessed political subdivision after a project has been in existence for at least one year, shall hold a hearing to determine the benefits of the project to each tract of land affected. Notice of the hearing must be given by publication once each week for three consecutive weeks, beginning at least thirty days before the hearing, in the newspaper 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 of the hearing in an envelope clearly marked “ASSESSMENT NOTICE” to each owner of land in the assessed district at the landowner’s address as shown by the tax rolls of the counties in which the affected property is located. 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. Regardless of the number of petitions received, the board is not required to conduct a reassessment more than once every ten years. An assessment or balance supporting a project fund may not be reduced or impaired by reassessment or otherwise so long as bonds payable out of the fund remain unpaid and moneys are not available in the fund to pay all the bonds in full, with interest. Costs of maintenance must be prorated in accordance with any adopted plan for reassessment of benefits.