Sec. 7. (a) Upon approval of the commission and subject to subsection (b), any person, whether or not the owner of land contiguous to or encompassing a watercourse, may divert the flood water of a watercourse for any useful purpose, including the purpose of storage.
(b) A diversion under this section may not cause injury to landowners or the users of water in the watershed of the watercourse from which the flood flow is diverted.
(c) This section does not limit:
(1) any rights granted under section 4 of this chapter or under IC 13-2-1-3(2) (before its repeal); or
(2) any other legal right existing on March 12, 1959, to divert and store water.