S.D. Codified Laws § 11-11-65
In the discretion of the authority, the bonds may be secured by a trust indenture by and between the authority and a corporate trustee, which may be any trust company or bank having the power of a trust company within or without the state. Such trust indenture may contain such provisions for protecting and enforcing the rights and remedies of the bondholders as may be reasonable and proper and not in violation of law, including covenants setting forth the duties of the authority in relation to the exercise of its corporate powers and the custody, safeguarding, and application of all moneys. The authority may provide by such trust indenture for the payment of the proceeds of the bonds and the revenues to the trustee under such trust indenture or other depository, and for the method of disbursement thereof, with such safeguards and restrictions as it may determine. All expenses incurred in carrying out such trust indenture may be treated as a part of the operating expenses of the authority. If the bonds shall be secured by a trust indenture, the bondholders shall have no authority to appoint a separate trustee to represent them.
SDCL 11-11-65