S.D. Codified Laws § 34A-1-64

Any funds received by the state from the mitigation fund shall be deposited into the clean air act settlement fund that is hereby created. The funds shall be administered by the secretary for the purpose of facilitating the improvement and protection of the ambient air quality throughout the state by reducing nitrogen oxide air emissions from mobile sources pursuant to a beneficiary mitigation plan developed by the department and approved by the board. The department's administrative costs of implementing the mitigation fund will be paid from the clean air act settlement fund through the air quality subfund established in § 34A-1-59. Any interest earned on the clean air act settlement fund shall be returned to the mitigation fund.