S.D. Codified Laws § 27A-13-5
Every person who is admitted to the center on a voluntary basis shall, prior to his admittance, tender to the administrator of the facility the minimum amount charged against the counties in § 27A-13-16. If this sum is not tendered, the person shall have an authorization to be admitted and a pledge to pay the minimum amount by the county commissioners of his county of legal settlement or a pledge from any other responsible governmental entity. If the person is indigent, his county is obligated to pay the admission fee and cost of care.
Continued voluntary treatment without commission or governmental approval shall be contingent upon an advance monthly payment according to ability to pay but in no instance may it be less than the minimum amount.
SDCL 27A-13-5