Navigating the Reissuance of the PAG-13 General Permit

• May 8, 2025
• Written by: Kara Kalupson
• Perspectives

Introduction

As municipalities across Pennsylvania prepare for the reissuance of the PAG-13 General Permit by the Pennsylvania Department of Environmental Protection (PA DEP), it’s crucial to understand the implications of this significant regulatory shift. At RETTEW, we believe informed decision-making and proactive planning are key to navigating these changes effectively. 

Understanding the Reissuance

The PA DEP’s plan to reissue the PAG-13 General Permit, which authorizes the discharge of stormwater from regulated small Municipal Separate Storm Sewer Systems (MS4s) to surface waters, marks a pivotal moment for stormwater management. The previous permit expired on March 15, 2023, and has been administratively extended to ensure continued regulatory coverage until the new permit is finalized.

The reissuance is driven by the expiration of the original 2018 PAG-13 permit. This administrative extension is a temporary measure to maintain compliance and protect Pennsylvania’s water resources. The transition to a new permit is essential for adapting to evolving environmental standards and ensuring sustainable stormwater management practices.

The reissuance impacts 493 MS4s in Pennsylvania? currently covered under the PAG-13 General Permit, as well as newly designated MS4s from the 2020 census seeking new coverage. It’s important to distinguish between municipalities with general permits and those with individual permits, which have individual requirements and permit terms. and are not affected by the general permit requirements. Understanding these distinctions is crucial for effective planning and compliance.

Timeline for Implementation

Based on the draft permit, municipalities must submit their Notice of Intent (NOI) to PA DEP by September 30, 2026. This deadline sets the stage for the new permit to take effect around March 2027. While public input was received in mid-February 2025, PA DEP has yet to establish an internal deadline for addressing comments, adding a layer of uncertainty to the timeline.

Key Changes to Anticipate

Several significant changes are proposed in the new PAG-13 General Permit:

1. Transition from Pollutant Reduction Plans (PRPs) to Volume Management Plans (VMPs): PRPs will be phased out as they have been completed under the 2018 permit. Instead, municipalities will now focus on developing VMPs, which are due two years after submitting required volume calculations.
2. Introduction of the MEP Calculator: Municipalities must use the Maximum Extent Practicable (MEP) Calculator to determine the stormwater volume they need to manage. These calculations must be submitted with the Notice of Intent (NOI) by September 30, 2026.
3. Adoption of the 2028 Model Stormwater Ordinance: Municipalities will be required to adopt the updated model stormwater ordinance by 2028, ensuring consistency in stormwater management practices.
4. Updates to Minimum Control Measures: Minor changes will be made to the existing minimum control measures, which are essential for effective stormwater management.
5. Additional Minor Changes: Other proposed updates include adjustments to renewal NOIs, references to the 2020 census data, and eligibility criteria for permit coverage.

These changes represent a significant shift in focus from pollutant reduction to volume management, requiring municipalities to adapt their stormwater management strategies accordingly.

Addressing Municipal Concerns

The shift from pollutant reduction to volume management has raised concerns among municipalities. During the PRP phase, PA DEP indicated that overachieving sediment reduction could be credited for future permits. However, the new permit focuses on volume reduction, leading to uncertainty about how previous efforts will be recognized.

Moreover, the introduction of socioeconomic factors into the volume calculation adds complexity. Municipalities can reduce their requirements based on population income levels, but this approach does not address the root causes of stormwater issues. Collaboration among municipalities on the NOI is encouraged, but it also raises questions about the effectiveness of these measures.

RETTEW’s Role in Supporting Municipalities

At RETTEW, we have extensive experience in supporting municipalities with MS4 permit requirements. Our expertise in VMP calculations and stormwater management ensures our clients can navigate these regulatory changes with confidence.

RETTEW assists municipalities in calculating the total volume of stormwater runoff, determining credits for existing stormwater management facilities, and developing VMPs for future projects aimed at reducing stormwater volume. Additionally, we provide support for ongoing MS4 permit requirements, including public education, mapping, and inspections.

RETTEW has a proven track record of designing effective bioinfiltration basins and infiltration practices. We alleviate the complexities for our clients, ensuring each project is executed flawlessly. We are committed to providing the necessary guidance and support to meet PA DEP regulations and safeguard Pennsylvania’s water resources.

Learn more about RETTEW’s stormwater management services and MS4 programs here.

Conclusion

The reissuance of the PAG-13 General Permit represents a significant shift in stormwater management for Pennsylvania municipalities. Understanding these changes and preparing for the new requirements is crucial. RETTEW is dedicated to helping our clients navigate this transition and achieve compliance with PA DEP regulations. Together, we can ensure effective stormwater management and protect Pennsylvania’s water resources.