No irrigation district shall in any year issue warrants in excess of ninety percent of the levy for such year, except that in case of due and outstanding obligations against the district contracted prior to the year in which any levy is made, the district board shall have the power to make an additional levy not to exceed one and four-tenths cents on each one hundred dollars upon the taxable value of all the taxable property in such district to create a special fund for the payment of past-due obligations. If the claims or obligations against any fund for any year are fully paid, the board shall have the power to transfer any unused balance to any fund for any preceding or succeeding year.