The Connecticut Department of Energy and Environmental Protection (CT DEEP) issued the General Permit for Discharge of Stormwater Associated with Industrial Activities under the National Pollutant Discharge Elimination System (NPDES) on October 1, 2025. The 2025 Industrial General Permit (IGP) regulates discharge of stormwater from industrial facilities to the surface waters of Connecticut. The 2025 IGP provides consistent coverage across a wide variety of industries, but recognizes, through sector-specific requirements, that different industries may have different challenges and opportunities associated with stormwater protection.

Facilities falling under one of the 32 covered industrial sectors and operating in one or more of the listed Standard Industrial Classification (SIC) or North American Industrial Classification System (NAICS) codes should review their operations for activities that might be exposed to stormwater. These may include storage or transport of products or raw materials, waste or scrap storage, and loading or unloading areas.

What Does the IGP Require?

Facilities covered under the 2025 IGP are obligated to post signage about their coverage, conduct inspections of the facility, train personnel, maintain records, submit annual reports, conduct periodic discharge monitoring and reporting, and develop and implement a Stormwater Pollution Prevention Plan (SWPPP).

Covered facilities will be subject to specific requirements based on their industrial sector, location, receiving waterbodies, and operations. Monitoring and sampling requirements – including parameters and frequency – vary by industrial sector, but every sector has some requirements. Sector-specific monitoring may include testing stormwater for specific pollutants, monitoring for aquatic toxicity conditions, and conducting benchmark monitoring to evaluate the effectiveness of control measures. Facilities discharging to impaired waterways may have additional monitoring requirements. When warranted, facilities must take corrective actions in a timely manner to address or prevent stormwater pollution. The 2025 IGP specifies timelines based on the type and severity of the issue requiring corrective action.

The SWPPP identifies facility personnel who are responsible for maintaining compliance with the IGP and preventing stormwater pollution and explains the stormwater management practices and procedures in place. It also describes features of the facility that are relevant to preventing stormwater pollution, such as:

• Potential pollutant sources, such as operations that are exposed to or potentially exposed to stormwater
• Stormwater outfalls
• Drainage patterns
• On-site swales, retention ponds, and other features
• Receiving waters, and other nearby surface waters and wetlands
• Measures to increase site resilience to extreme weather events and long-term climate impacts

What’s Changed from the 2021 IGP?

The 2025 IGP reflects several changes made to align with other EPA and CT DEEP requirements. These include new requirements for electronic registration and reporting, and submittal of annual reports by April 15. Additionally, there are new or expanded inspection and monitoring requirements for most industrial sectors. These include new quarterly visual monitoring assessments; changes to monitoring procedures, frequencies, and parameters for certain activities; inclusion of additional water quality-based effluent limits and benchmarks; and incorporation of Effluent Limit Guidelines (ELGs) for specific industrial sectors. The Control Measures section of the 2025 IGP now reflects developing technologies and industrial practices. A new permit section details when and how all sectors will be required to implement corrective actions; the response timeline now depends on the type and severity of the issue requiring correction. Changes to SWPPP requirements include discussion of facility resilience and response to serious climate and weather events.

When Do I Register?

Registration under the new IGP begins on November 1, 2025.

• Facilities covered under the 2021 IGP must register by April 1, 2026. Interim permit coverage is granted by CT DEEP, provided a timely registration under the 2025 IGP is received.
• New facilities in need of IGP coverage must register 90 days prior to the date the industrial activity is initiated.
• Facilities under new ownership must register within 30 days of the transfer of ownership, and existing permittees must submit a Notice of Termination. The IGP is non-transferable.
• Facilities that do not have any operations exposed to stormwater may be eligible to submit a No-Exposure Certification instead of an IGP registration.

CT DEEP will take approximately 90 to 180 days to process each registration.

How Do I Register?

Registration must be completed using CT DEEP’s online ezFile Portal. The following information must be provided:

• Operator and facility details
• SIC/NAICS codes
• Site location and drainage information
• Receiving water body information
• NDDB and Coastal Consistency reviews
• All discharge points
• A completed SWPPP, certified by Facility representatives and a CT Professional Engineer (P.E.) or a Certified Hazardous Materials Manager (CHMM)

There is a registration fee, which is based on employee count and gross sales; municipalities are eligible for a 50% discount on registration fees.

How Can I Get Some Help with This?

IGP registration is opening soon, SWPPP updates can be challenging, and the deadlines are tight— expert help is a must! Trinity’s New England-based team offers consultations, regulatory guidance, and registration support to help industrial facilities:

• Evaluate your compliance needs
• Prepare and submit a complete IGP registration package
• Update or develop your SWPPP and have it certified by a CT P.E. or a CHMM
• Identify Best Management Practices to help your facility prevent stormwater pollution
• Train your Stormwater Pollution Prevention Team
• Prepare and submit required stormwater reports
• File a No Exposure Certification or Notice of Termination of coverage, if appropriate

Reach out today to Trinity’s New England-based experts at 508.273.8600 to discuss your Facility’s stormwater compliance needs.

Trinity reviewed the draft IGP in October 2024. Check out our on-demand webinar for more information.