Indiana Department of Environmental Management (IDEM) - MS4 regulator

The Indiana Department of Environmental Management (IDEM) is the state agency that issues and enforces NPDES/MS4 stormwater permits for municipalities in Indiana. IDEM administers the MS4 permit covering the City of Indianapolis and Marion County, which requires stormwater planning, public education, illicit discharge detection, and annual reporting. IDEM conducts inspections and may take enforcement actions for permit noncompliance within Indianapolis.