If there are unpaid matured warrants, other than warrants payable from operation and maintenance assessment levies, on January 1st in any year, the board shall call and collect such portion of the principal and interest of any available outstanding unbonded assessment, other than an operation and maintenance assessment, as is necessary to pay such warrants and any other warrants, other than operation and maintenance warrants, which shall mature within 90 days after January 1st.