§ 299-q. Expense of the improvement. The cost of establishment of a watershed district and the furnishing of the improvement therein shall include the amount of all contracts, the costs of all lands and interests therein necessarily acquired, the costs of erection of necessary buildings for operation or administration of the improvement, the costs of necessary original equipment for operation or administration of the improvement, printing, publishing, interest on loans, legal and engineering services and all other expenses incurred or occasioned by reason of the establishment of the watershed district and the furnishing of the improvement. In addition, there shall be apportioned against, charged to and included in such cost such allowance as the board of supervisors may make for expenditures made by the initiating agency which are directly attributable to the establishment of the watershed district, as well as for any services rendered by the county attorney, the county engineer or any other salaried county officer or employee, when such services have been necessary to or occasioned by reason of the establishment of the watershed district.