After the list of lands with the assessed benefits and the decree and judgment of court have been filed in the office of the clerk of the court of common pleas, as provided in § 49-19-1090, then the board of supervisors shall, without any unnecessary delay, levy an assessment, hereinafter called a tax, of such portion of the benefits on all lands, railroads and other property in the district to which benefits have been assessed as may be found necessary by the board of supervisors to pay the costs of the completion of the proposed works and improvements as shown in the Plan of Reclamation and in carrying out the objects of the district and in addition thereto ten per cent of such total amount for emergencies. The tax shall be apportioned to and levied on each tract of land in the district in proportion to the benefits assessed and not in excess thereof. In case bonds are issued as provided in Article 15 of this chapter the amount of the interest, as estimated by the board of supervisors, which will accrue on the bonds shall be included and added to the tax. But the interest to accrue on account of the issuing of such bonds shall not be construed as a part of the costs of construction in determining whether or not the expenses and costs of making the improvements are or are not equal to or in excess of the benefits assessed.