RIPDES Stormwater Municipal Separate Storm Sewer Systems (MS4s) Permittees/Operators

News and Updates

  • Status of MS4 General Permit Re-issuance: On Pause for 2024

Stormwater Coordinators

Each MS4 has designated one person to be their Stormwater Coordinator. For a list of contact, please visit: MS4 Stormwater Coordinators List

** If the designated Stormwater Coordinator for your MS4 has changed, please notify RIDEM of the name and contact information of the new stormwater coordinator ASAP by emailing Jennifer Stout of the RIPDES Program at **

Importance of Record Keeping and Tracking

While many MS4s may be completing some of the required measurable goals, there is a general lack of record keeping, tracking, and documentation that prevents some MS4s from demonstrating compliance with the MS4 General Permit. Not only does setting up a system for record keeping and tracking help with compliance, it can also help an MS4 understand its day-to-day operations and use that information for future planning and resource allocation. It provides valuable information to Town Councils to help appropriate the needed funding to perform the required operations for stormwater management and maintenance.

Operations & Maintenance ...of MS4-Owned Systems:

The 2003 MS4 General Permit requires MS4s to identify all structural BMPs, and develop schedules for inspections, cleaning and repair of structural BMPs, detention/retention basins, storm sewers and catch basins with appropriate scheduling given intensity and type of use in the catchment area. The MS4 must at a minimum incorporate all permit requirements and maintenance specifications of the particular BMP. Maintenance schedules must address issues related to the performance of BMPs observed during their inspection. The operator must make changes to the frequency of maintenance of structural BMPs when dry weather surveys of outfalls and inspections of the system and BMPs reveals that the maintenance frequency is not adequate. The operator must maintain records on inspections and maintenance performed on structural BMPs

...of Privately-Owned BMPs:

The 2003 MS4 General Permit required MS4s to identify existing storm water structural BMPs discharging to the MS4 with a goal of ensuring their long term O&M of the BMPs. As part of the post-construction program, MS4s are also required to develop and implement procedures with a goal of ensuring the long-term O&M of BMPs constructed for new land development and re-development. MS4s must also implement strategies to help ensure that future O&M responsibilities are clearly identified.

Outfall Mapping

In accordance with the 2003 MS4 General Permit, Rhode Island MS4s were required to identify, locate, and map all outfalls from their stormwater system that discharge to waters of the State. RIDEM has taken the data provided by the MS4s and created a GIS layer with the outfall information. To view the data, go the MS4 Resource Map and select the “Stormwater Outfall” layer at the following link: MS4 Resource Map.

** If the outfall data for your municipality/MS4 is missing or incorrect, please contact Paul Jordan at to provide the most current and accurate data. **

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