On or before the first day of November of each year the diking commissioners shall, and on or before the first Monday in October of each year the drainage commissioners shall, make and certify to the county auditor an estimate of the cost of maintenance and repair of the improvement for the ensuing year. The amount thereof shall be levied against the land in the district in proportion to the maximum benefits assessed, and shall be added to the general taxes and collected therewith. If such estimate of the cost of maintenance and repair against any tract or contiguous tracts owned by one person or corporation is less than two dollars, then the county auditor shall levy such a minimum amount of two dollars against such tract or contiguous tracts, and upon the collection thereof as herein provided shall pay all sums collected into the maintenance and/or repair fund of the district. In case of an emergency the commissioners may incur additional obligations and issue warrants therefor in excess of the estimate.