It shall be the duty of the board to make a levy each year for a sinking fund, which shall, with cash actually on hand and lawful investments in such fund, excluding taxes in process of collection, be sufficient to pay:
The foregoing formula shall be applied by said district each year in determining the amount necessary to raise by tax levy for sinking fund purposes, independently of actions taken in previous years, and if by omission to make a levy which could have been validly made for any bonds or interest coupons, or where from any cause the cash and valid investments in the sinking fund does not equal the accrual liabilities, it shall be the duty of said district to readjust the annual bond accrual in accordance with the foregoing formula in order that said bonds shall be paid when due, save and except only that where the cash and valid investments in the sinking fund at the close of any fiscal year, after reserving for interest accrued and accruing under the priority therefor as contained in Section 9C of Article X of the Constitution of the State of Oklahoma, is insufficient to pay and retire any bonds matured or to mature before another tax levy may be made and collected and no action has been instituted to refund such matured bonds, it shall be the duty of said district to include, in addition to interest thereon or aforesaid, an accrual therefor in an amount equal to the bonds so matured or to mature or the annual accrual first lawfully applicable to the issue thereof, whichever is the lesser.
It is the sole intention of this act to require that sinking funds be applied as provided by Section 9C of Article X of the Constitution of the State of Oklahoma.
Okla. Stat. tit. 19, § 1710