Section 29217 Of Article 4. Refunding Bonds From California Public Utilities Code >> Division 10. >> Part 2. >> Chapter 8. >> Article 4.

. If the earliest maturity of the refunding bonds is more than one year after the date of issuance, the board shall levy and collect annually a tax sufficient to pay the interest as it falls due and to constitute a sinking fund for payment of the principal on or before maturity.