After the main improvement in any drainage district, or drainage and levee district, has been completed, the board of directors, if it deems necessary for the protection of the district, and for the proper maintenance of the efficiency of the improvement, may employ a competent person to look after and take care of the same. The person so employed shall be designated “drainage overseer.” The board of directors shall define the duties of the drainage overseer, and contract with the drainage overseer to perform the prescribed duties, and contract for the amount to be paid the drainage overseer for such services. The board of directors has the right, at any time, to discharge the drainage overseer and employ another whenever, in its judgment, it is to the best interest of the district that it be done. The compensation of the drainage overseer shall be paid out of any funds in the district, not needed for the payment of bonds and interest maturing, and other improvements that are to be made, during the year. The payment will be made as is provided for other payments under the drainage law.