S.D. Codified Laws § 11-11-74
All moneys held in any capital reserve fund, except as provided in § 11-11-73, shall be used, as required, solely for the payment of the principal of bonds secured in whole or in part by such fund or of the debt service fund payments hereinafter mentioned with respect to such bonds, the purchase or redemption of such bonds, the payment of interest on such bonds, or the payment of any redemption premium required to be paid when such bonds are redeemed prior to maturity; provided, however, that moneys in any such fund shall not be withdrawn therefrom at any time in such amount as would reduce the amount of such fund to less than the maximum capital reserve requirement established for such fund as provided by § 11-11-71 except for the purpose of making with respect to bonds secured in whole or in part by such fund payments, when due, of principal, interest, redemption premiums, and the debt service fund payments mentioned in § 11-11-71 for the payment of which other moneys of the authority are not available.
SDCL 11-11-74