S.C. Code Ann. § 11-13-20

To facilitate the disbursement of public monies, the State Treasurer shall deposit in such bank or banks or trust companies in this State as shall be agreed upon by the State Fiscal Accountability Authority or a majority thereof, and as in its opinion shall be secure, all monies belonging to the State, other than those he may keep in the safe in the vault of the designated bank or trust company, the monies so deposited to be placed to the credit of the State Treasurer. Such deposits shall draw the best rate of interest obtainable.