S.D. Codified Laws § 7-21-48
The board of county commissioners may transfer the surplus moneys that may be on hand in any of the several funds to such fund or funds as they may deem for the best interest of the county or may appropriate such surplus moneys to the payment of any outstanding indebtedness of the county. No moneys in any fund shall be transferred therefrom unless there be left in such fund sufficient money to pay all outstanding warrants drawn against such fund, together with any other indebtedness or contemplated expenditures from said fund for the current fiscal year. No money shall be transferred from any sinking or interest fund unless sufficient money be left therein to pay all interest which may accrue on and the principal of all outstanding bonds.
SDCL 7-21-48