S.D. Codified Laws § 4-7-32
On July first of each fiscal year or at such time that the prior fiscal year general fund ending unobligated cash balance is determined, the commissioner of the Bureau of Finance and Management shall transfer all prior year unobligated cash up to an amount equal to ten percent of the general fund appropriations from the general appropriation act for the prior fiscal year into the budget reserve fund. In no event shall the cash balance in the budget reserve fund be greater than ten percent of the general fund appropriations from the general appropriation act for the prior fiscal year.
Expenditures out of the budget reserve fund shall only be by special appropriation of the Legislature and shall only redress such unforeseen expenditure obligations or such unforeseen revenue shortfalls as may constitute an emergency pursuant to S.D. Const., Art. III, § 1.
SDCL 4-7-32