In order to implement the flat rate assessments authorized in section 43-701B, Idaho Code, the board of directors, before any list of tracts is certified to the county officers as provided for in section 43-701C, Idaho Code, or before the list is used by the district for collection of flat rate assessments utilizing its own personnel and procedures, shall assess, against all tracts it has determined to assess at a flat rate as in this chapter provided, the entire unpaid balance of principal and any accrued interest on any contract or bonded indebtedness apportioned to each such tract. If any landowner shall object to such assessment, his tract of land shall not be included in the list certified to the county officers, and that tract shall be assessed by the district in the regular manner for all purposes, instead of under the flat rate procedure authorized in this chapter.