Indiana Code Title 13. Environment § 13-21-5-20

Sec. 20. (a) After a district submits a district plan to the department under this chapter, a district may merge with one (1) or more other districts after the adoption of identical resolutions by the board of each district to be merged.

(b) Upon adoption of identical resolutions under subsection (a), a board for the resulting merged district shall be established using the procedures set forth in IC 13-21-3.

(c) A merged district shall:

The new district plan may be an amended version of the previous approved plans submitted under the new district name.  A merger under subsection (a) does not take effect until the district plan is filed with the commissioner.

(d) A district plan adopted under this section is considered approved unless the commissioner notifies the district in writing not later than thirty (30) days after the district plan is filed with the commissioner that the district plan fails to comply with the state plan.  The notice provided by the commissioner must include comments concerning changes to the district plan that would make the district plan acceptable.