Any ditch or canal constructed before July 1, 1917, of sufficient capacity to water the lands for which the water was appropriated, together with the land subject to be watered by the ditch, canal, or franchise, is exempt from the operation of this chapter, unless an irrigation district is formed under the provisions of this chapter for the purpose of purchasing the ditches, canals, and franchises. This chapter and chapters 46A-5 to 46A-7, inclusive, do not affect the rights of ditches already constructed.
SDCL 46A-4-9