Program Updates
House Enrolled Act 1037
HEA 1037 made changes to Indiana Code (IC 36-1-3-14) and became effective on May 1, 2025. This law change impacts local construction stormwater ordinances, including those adopted by local Municipal Separate Storm Sewer Systems (MS4s). In general, a local law, rule, ordinance, or regulation cannot be more stringent than the requirements of IDEM’s construction stormwater general permit. Any law, rule, ordinance, or regulation that is more stringent than IDEM’s CSGP is void and the local entity must administer their local program in accordance with the CSGP. Note: this is true although the CSGP makes some general references to compliance with MS4 ordinances and local requirements. The law now prohibits more stringent local requirements.
IDEM provides guidance on the requirements and applicability of the CSGP which local entities and MS4s can reference as they review their ordinances to ensure they are consistent with CSGP requirements. The guidance is based on IDEM’s administration of the CSGP for those areas of the state where the agency retains primary regulatory authority. The topics below include information related to the changes made by HEA 1037:
General Information Related to the CSGP
Larger Common Plan of Development (Clarifies the authority of IDEM to regulate projects sites less than one (1) acre) of land disturbance)
- Applicability of the Construction Stormwater General Permit
- In addition to the Applicability Section: Guidance has been developed for specific project types and implementing larger common plan (Guidance Document [PDF] )
Stormwater Permitting
The Stormwater Program is responsible for issuing permit coverage and monitoring compliance for stormwater associated with industrial activity, construction activity, and municipal separate storm sewer systems (MS4s).
- Construction Stormwater General Permit (CSGP):
- IDEM administers a general permit program that targets construction activities that are associated with land disturbance of one (1) acre or more. The construction stormwater program is intended to reduce pollutants, principally sediment, which are a result of soil erosion and other activities associated with land-disturbing activities.
- An option for the general public to view projects with permit coverage under the CSGP is available on nSITE Explorer.
- Industrial Stormwater Permitting (327 IAC 15-6):
- IDEM administers a general permit program that targets stormwater run-off associated with industrial activities. Requirements of this rule apply to specific categorical industrial facilities, which are exposed to stormwater.
- Municipal Separate Storm Sewer Systems (MS4):
- IDEM administers a stormwater program that specifically targets local cities, towns, universities, colleges, correctional facilities, hospitals, conservancy districts, homeowner's associations and military bases located within urbanized areas, as defined by the U.S. Census Bureau. These designated MS4s are required to develop a local stormwater program. Most MS4s in Indiana operate under a general MS4 permit, while several others, based on population, are issued individual permits.