S.D. Codified Laws § 28-5A-1
In addition to the other powers granted to the Department of Social Services under chapter 28-1, the department may cooperate with or enter into agreements with agencies of the federal government to the extent necessary or appropriate to implement the provisions of Public Law 92-603, Social Security Amendments of 1972, as amended to January 1, 2004, including the power to agree to administer all or part of the supplemental security income program of the federal government, to provide, under such rules as may be promulgated by the department, for supplementary payments to qualified residents of South Dakota who are receiving or would be eligible to receive supplemental security income under Title XVI of the Social Security Amendments of 1972, as amended to January 1, 2004, or any other agreement which would be of benefit to the citizens of this state.
SDCL 28-5A-1