SW

Stormwater Directory

Indiana

Indiana Department of Environmental Management

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Quick Summary

For most Indiana projects disturbing 1 acre or more, you need a Rule 5 (INR100000) Construction General Permit and a SWPPP. The flat $100 fee is one of the lowest in the region.

State-DelegatedVerified 2026-03

Construction Permit

Permit Document ↗
Permit Name
NPDES Construction Stormwater General Permit (Rule 5 / Permit INR100000)
Threshold
≥ 1 acre of land disturbance; < 1 acre if part of a larger common plan of development or sale
NOI Lead Time
NOI must be submitted and approved before earth-disturbing activities begin; no fixed calendar lead time is prescribed, but IDEM review typically takes several business days
Application Method
Online via IDEM's myidem.in.gov portal (electronic NOI submission); paper NOI also accepted but online is preferred
Fee
$100 per NOI filing (flat fee); no acreage-based scaling
Permit Expires
January 31, 2028
Apply for Permit ↗

SWPPP Requirements

Permit Document ↗
SWPPP Required
Yes
PE Cert Required
No
Template Available
Yes
SWPPP must be prepared prior to submitting the NOI and must be on site and available for inspection throughout the project. IDEM provides a Rule 5 SWPPP template and construction plan checklist on its website. A PE stamp is not required for the SWPPP itself, though local drainage plans may require engineering sign-off. The SWPPP must be updated whenever site conditions change significantly.

Inspection Requirements

Permit Document ↗
Frequency
At least every 7 days and within 24 hours after a storm event producing ≥ 0.5 inches of rainfall in a 24-hour period; frequency may be reduced to every 14 days when the entire site is temporarily stabilized or runoff is unlikely due to winter conditions
Rain Trigger
Within 24 hours of a storm event producing ≥ 0.5 inches of rainfall in a 24-hour period
Inspector Qualification
Inspections must be conducted by a qualified inspector who is knowledgeable about the permit requirements and BMP implementation; Indiana does not mandate a specific state-issued certification, but IDEM recommends Certified Inspector of Sediment and Erosion Control (CISEC) or equivalent training
Accepted Certifications
IDEM-approved training effectively required; licensed PE/RLS also qualifies; CPESC, CESSWI accepted in conjunction with Indiana-approved training

Discharge Standards

Permit Document ↗
Turbidity Limit
No numeric NTU effluent limit in the general permit; narrative standard applies
Indiana's Rule 5 permit does not establish a numeric turbidity limit. Discharges must not cause or contribute to a violation of the state's water quality standards (narrative turbidity and color standards at 327 IAC 2-1-6). Visual monitoring is required at all discharge points. If a discharge causes visible turbidity in the receiving water, corrective action is required.

Post-Construction

IDEM ↗
Required
Yes
Post-construction stormwater quality management is required under Rule 13 (327 IAC 15-13) for regulated MS4 communities and under Rule 15 (327 IAC 15-15) for certain construction projects discharging to regulated MS4s. Requirements include long-term operation and maintenance of structural BMPs. Specific design standards (volume capture, infiltration) are set by the local MS4 entity.

Impaired Waterbody / TMDL Requirements

Standard Provisions

Indiana IDEM's construction stormwater permit has standard provisions. No specific heightened requirements are triggered by impaired water body status in the general permit; standard stormwater BMPs and erosion controls apply statewide.

Program Contact

Contact Page ↗
Email
Stormwat@idem.IN.gov

State-Specific Notes

Indiana's construction stormwater program is commonly called 'Rule 5' after 327 IAC 15-5. IDEM issues a state general permit (INR100000) rather than delegating to counties. Operators of sites ≥ 5 acres must also submit a Notice of Termination (NOT) when construction is complete and final stabilization is achieved. Sites < 1 acre that are part of a common plan of development still need coverage. IDEM publishes a Land Quality Rule 5 Technical Guidance Manual that is widely used in practice.

Disclaimer: This information is provided for general reference only and may not reflect the most current regulatory requirements. Always consult the IDEM website and applicable regulations before beginning any construction activity.