S.D. Codified Laws § 46A-6-36
If an irrigation district organized under the laws of this state enters into a contract with the United States for the payment of charges due the United States in connection with a federal reclamation project, and the district contract is inconsistent in any respect with the individual water right contracts between the United States and the landowners of the district, the district contract will be taken as amendatory of individual water right contracts affecting district land, the owners, mortgagees, or lienors of which fail to answer the petition. However, the contract entered into with the United States, providing for a different deficiency assessment, shall be approved by a majority vote of the owners of land at an election properly called for such purpose.
SDCL 46A-6-36