Indiana Code Title 13. Environment § 13-16-1-3

(1) may be based on the average of the costs specified in section 2 of this chapter for all permits of that type or class;

(2) may be set at a particular amount in consideration of the type and amount of discharge or emission to which the permit relates;  and

(3) may not be different in amount for public sector permit holders than for private sector permit holders, unless the difference is specifically authorized by the Indiana Code.