Connecticut DEEP Releases Updated Industrial Stormwater General Permit

Registration under the new permit

The Connecticut Department of Energy and Environmental Protection (DEEP) released its new General Permit for the Discharge of Stormwater Associated with Industrial Activities (IGP) on October 1, 2025, and it went into effect on November 1, 2025. The new IGP has been updated to mirror formatting from the EPA General Permit and includes new sector designations and enforcement. All current facilities will have to reregister by April 1, 2026. Below is a summary of the new registration requirements for the IGP:

• Electronic application through ezFile
• Subscriber agreement through NetDMR
• Registration fee has increased ($625 or $1,250, depending on employee count and gross sales/municipal) and paid through ezFile
• SWPPP must be updated using the new DEEP SWPPP template prior to reregistration, must be certified by a Qualified Professional (i.e. CT licensed PE or CHMM), and must be submitted to the DEEP
• SWPPP site plan must be updated to include additional information, including but not limited to locations of curbs and historical spills
• New signage requirement indicating permit coverage within 180 days of coverage
• The SWPPP must be made available to the public at no cost

Any new proposed industrial activities for a site not previously registered must submit an application for approval to the DEEP on or before 90 days prior to the date the industrial activity is initiated for that facility. Once registered, any changes to the site or modifications to the industrial activities at a facility must be submitted to the DEEP.

What are you responsible for?

Once registered, facilities will be required to monitor their site and stormwater discharges, conduct inspections, maintain their site, and perform correct actions to remain in compliance.

Monitoring has been shifted to follow the calendar year, with the first quarter sampling starting on January 1, 2026.  All outfalls, including those that were exempted from sampling due to prior testing results under the benchmark limits, will need to be sampled for the full set of standard parameters.

• Quarterly visual assessments of each discharge point/outfall
• Semi-annual sampling of each outfall in January-June and July-December (not including any additional parameters that may be required in your designated sector, impairments for the receiving waterbody, or effluent limits)
• One (1) aquatic toxicity sample during the second half of 2026

All report submittals are moving to online submittal. This includes the quarterly visual assessments, the semi-annual discharge monitoring reports, annual reports (summary of VAs, DMRs, inspections, etc.), and noncompliance reports. The visual assessments and discharge monitoring reports must be submitted within 30 days of the end of the quarter/semi-annual period. The annual report must be submitted by April 15, the following year.

What will enforcement look like under the new permit?

With the issuance of the new permit, DEEP has included corrective actions and new reporting requires associated with the different action levels when a trigger is met. The new permit provides clarification on what is considered a permit violation. Triggers for a violation include:

• Benchmark exceedances (results exceeding daily limits or 2X above effluent limit)
• Ineffective BMP
• Unauthorized discharges or releases/spills
• Deficiencies found during an inspection
• Evidence of pollutants in a visual assessment or semi-annual sample
• Conditions that may endanger human health or the environment

These triggers result in the requirement to notify the Commissioner and different report timeframes. They also result in the requirement to conduct corrective actions.

Corrective actions follow a trigger event and are utilized to minimize or prevent pollutant discharges. The actions are broken up by timeframe and increase in complexity and price.

• Immediate action occurs within 12 days and consists of any actions necessary to minimize or prevent discharge until a permanent solution can be implemented. This may include sweeping and scheduling the installation of a new structure.
• Subsequent corrective action would occur within 14 days (prior to the next storm event) and may include installing or modifying a control measure or completing repairs. If the repair cannot occur within 14 days but can be completed in 60 days, documentation needs to be included.
• Extensions for corrective actions over 60 days must be included in the SWPPP.

The measures may increase from reviewing the SWPPP, reviewing sources of pollutants, and increasing housekeeping and inspections (cheapest and quickest controls) to implementing new control structures such as secondary containment or treatment structures such as filters, separators and retention basins (large projects, expensive, time-consuming).

Individual Permit Requirements

If a facility is registered for the General Permit and corrective actions cannot address pollutant sources at the facility, the site may be required to apply for an Individual Industrial Stormwater Discharge Permit.  Individual Permits are required by the Commissioner:

• If the facility has a unique discharge or the sampling results indicate that the facility cannot comply with the General Permit as required to protect wetlands, watersheds, and impaired waters.
• If Corrective Action Measures (structural source or water treatment control) does not resolve the corrective action trigger

Some of the differences between the General and Individual Permits include:

• Individual permits are issued directly to the applicant
• In-depth application with a higher fee
• Permits tailored to the site’s discharges, generally additional sampling parameters, and additional monitoring events (including dry weather sampling)
• Significantly more costs required for maintaining compliance with the Individual Permit
• Potential for consent orders and additional fines with continued non-compliance

The new CT General Permit for the Discharge of Stormwater Associated with Industrial Activities (IGP) can be found at the DEEP’s webpage here.

B&L has been assisting Connecticut clients with various compliance requirements for this General Permit since the early 90s and is here to help with all of your needs. For more information regarding the DEEP’s IGP registration process and permit requirements, please contact Jeff Bogoian, Managing Engineer.