Sec. 5. (a) Subject to subsection (b), a person, firm, or corporation operating a water flood project using potable ground water on March 14, 1957, may do the following:
(1) Continue the flood.
(2) Use the additional potable water that is necessary.
(b) If an emergency arises affecting the water supply for household or farm use, the department may, after notice and hearing, order the person, firm, or corporation to cease the use of the potable ground water.