Indiana Code Title 14. Natural and Cultural Resources § 14-25-15-5

(1) except as provided in subdivision (2), may not:

any mandatory program governing water conservation and efficiency under section 4.2 of the compact;

(2) may adopt rules to establish a mandatory program governing water conservation and efficiency under section 4.2 of the compact only if the general assembly adopts an act authorizing the adoption of the rules;

(3) shall adopt rules under IC 4-22-2 that implement voluntary water conservation and efficiency programs;  and

(4) shall adopt rules under IC 4-22-2, which may provide for general permits, for the implementation, administration, and enforcement of article 4 of the compact.