Cal. Pub. Resources Code § 5311
If sufficient bids are not received to consume the money in the sinking fund, and a sum sufficient for the purpose still remains in the sinking fund, notice shall be given by advertisement for not less than thirty days, stating that there is an amount, to be specified in the notice, still remaining in the sinking fund to be applied to the redemption of the bonds with interest, having the highest numbers, specifying the numbers. If those bonds are not presented for redemption, surrender, and cancellation within the time specified in the notice, they shall thereafter cease to draw interest. The amount in the sinking fund shall be kept for their redemption when presented, but no more shall be paid than the amount of principal and interest due at the expiration of the time specified in the notice.
Ca. Pub. Res. Code § 5311