Whenever there shall have accumulated in any general or special fund of a district money, the disbursement of which is not yet due, the board of commissioners may, by resolution, authorize the treasurer to deposit or invest such money in qualified public depositaries, or to invest such money in any investment permitted at any time by RCW
36.29.020. However, the county treasurer may refuse to invest any district money the disbursement of which will be required during the period of investment to meet outstanding obligations of the district.