If for any cause the improvements shall not be made, said costs shall be charged on the real property in the district, including railroads, if any, and shall be raised and paid by assessments in the manner hereinafter described; or, in the event said assessments are not made, or the improvements shall not be completed or the same be abandoned, for any cause, after such indebtedness is incurred, the board of supervisors of the county in which the drainage district is located shall levy an acreage tax, or an ad valorem tax, on the lands in said proposed district if the same has not been organized, or on the lands of the district if the same has been organized, the total collections from which shall be sufficient to pay such indebtedness. The board of supervisors may levy a sufficient tax in one year or may levy a succession of acreage taxes, or ad valorem taxes, over a period of years, not to exceed three years, to be determined by said board of supervisors. If an ad valorem tax be levied, the board of supervisors may use for that purpose the assessments of the land of the last assessment roll of the county in which said lands are situated. In case the lands in the proposed district lie in more than one county, then the chancellor aforesaid shall apportion said indebtedness between the several counties, and the boards of supervisors of the several counties shall thereupon levy such apportioned tax upon the lands of their counties respectively, according to the ruling of the said chancellor.