S.D. Codified Laws § 46A-7-7

If any irrigation district, organized under the laws of this state, has contracted with the United States for a supply of water for the irrigation of lands within the district, the construction of irrigation or drainage works, or the operation of such works, or both, or other purposes authorized by law, the board of directors may make the assessments intended to meet the obligations of the district under the contract in accordance with the method and terms as provided by the contract. No apportionment of benefits by the director of equalization is necessary if so provided in the contract.