S.D. Codified Laws § 46A-7-4
The director of equalization shall, between the first Monday in May and the first Monday in July in each year, examine each tract or legal subdivision of land in an irrigation district including entered and unentered public lands of the United States, subject to the irrigation district under the act of Congress approved August 11, 1916, entitled "An Act to promote the irrigation of arid lands," as amended to January 1, 2011. The director of equalization shall determine the benefits that will accrue to each tract or subdivision on account of the construction or acquisition of the irrigation works. The amount so apportioned or distributed to each tract or subdivision as finally equalized or confirmed by the court, as the case may be, is the basis for fixing the annual assessments levied against the tracts or subdivisions in carrying out the purposes of chapters 46A-4 to 46A-7, inclusive.
SDCL 46A-7-4