In any new, additional, or supplemental assessment of any reclamation district, the following shall be determined:
(a)
The amount that should be assessed upon each tract of land according to the benefits that accrued to each tract of land from the expenditures represented by the warrants of the reclamation district that have been exchanged or surrendered for or paid by warrants of the drainage district or of Sutter-Butte By-Pass Project No. 6 or any other unit or project.
(b)
The amount which should have been apportioned to each tract of land if the warrants of the drainage district or of Sutter-Butte By-Pass Project No. 6 or any other unit or project had been distributed to the tract of land or owner thereof proportionately to the percentage which the tract of land was assessed on the last assessment made by the reclamation district for the construction or acquisition of the levees, easements and property sold or transferred to the drainage district or any project thereof.