As of December 18, 2021, Indiana no longer administers the construction stormwater program under Indiana Administrative Code (327 IAC 15-5 or Rule 5). Permitting coverage is now issued under the Construction Stormwater General Permit (CSGP): https://www.in.gov/idem/stormwater/files/final_gen_permit_inra00000_construction.pdf
The CSGP is a performance-based regulation designed to reduce pollutants that are associated with construction and/or land-disturbing activities.
Additional information can be found here: https://www.in.gov/idem/stormwater/construction-land-disturbance-permitting/
MS4 boundaries for Indiana: https://www.in.gov/idem/cleanwater/ms4s-boundaries-map-for-indiana/
IDEM Regulatory Portal: https://stormwater.idem.in.gov/ncore/external/home