Municipal Separate Storm Sewer System (MS4)
The City of Fairfax is a Phase II Municipal Separate Storm Sewer System (MS4) and is regulated by the Virginia Pollutant Discharge Elimination System (VPDES) general permit through the Virginia Department of Environmental Quality. This permit allows the City of Fairfax to discharge stormwater per the state and federal laws created by the Clean Water Act. The MS4 permit annual report is a required document prepared by the City each permit cycle to outline the activities the City is doing to reduce stormwater runoff and pollution to the maximum extent practicable.
In 2023, DEQ approved a new general permit that became effective November 1, 2023, and expires October 31, 2028.
The MS4 Program must include an MS4 Program Plan that includes six minimum control measures and Special Conditions for approved Total Maximum Daily Loads (TMDL) for the Chesapeake Bay TMDL and non-Chesapeake Bay TMDLs. The six minimum control measures are:
- Public education and outreach
- Public participation/involvement
- Illicit discharge detection and elimination
- Construction site stormwater runoff
- Post-construction stormwater management in new development and redevelopment on prior developed lands
- Pollution prevention/good housekeeping for municipal operations
The City's MS4 permit contains the Notice of Coverage Letter(PDF, 363KB), information on minimum control measures, special conditions for Chesapeake Bay and non-Chesapeake Bay TMDLs, and their specific requirements.
Documents
- MS4 Annual Report - Year 2, 3rd cycle (2024-2025)(PDF, 512KB)
- MS4 Annual Report - Year 1, 3rd cycle (2023-2024)(PDF, 577KB)
- MS4 Program Plan (2024 update)(PDF, 1001KB)
- MS4 Annual Report - Year 5, 2nd cycle (2022-2023)
- MS4 Annual Report - Year 4, 2nd cycle (2021-2022)
- MS4 Program Plan (2022 update)(PDF, 965KB)
- MS4 Annual Report - Year 3, 2nd cycle (2020-2021)(PDF, 20MB)
- MS4 Annual Report - Year 2, 2nd cycle (2019-2020)
- MS4 Annual Report – Year 1, 2nd cycle (2018-2019)
- MS4 Program Plan (2019 update)(PDF, 2MB)
MS4 Stormwater System Map & Outfall Information
This map shows the city’s stormwater system, which is comprised of pipes, structures, inlets, outfalls, and publicly maintained stormwater management facilities (BMPs). The outfall information table provides details for each point where a conveyance of the city’s stormwater system discharges into streams, ponds, and wetlands.
Visit the following links to see a map of the stormwater outfall structure locations in the City.
Chesapeake Bay TMDL Action Plan
Local TMDL Action Plans
- Bacterial TMDL Action Plan, 2025 (Accotink Creek, Difficult Run, Popes Head Creek)(PDF, 5MB)
- Benthic TMDL Action Plan, 2025 (Accotink Creek, Difficult Run, Bull Run, Popes Head Creek)(PDF, 35MB)
- Chloride TMDL Action Plan, 2025 (Accotink Creek)(PDF, 11MB)
- Accotink Creek Chloride TMDL Action Plan, 2021 (Revised Feb 2022)(PDF, 2MB)
- Accotink Creek Sediment TMDL Action Plan, 2021(PDF, 18MB)
- Bull Run Sediment TMDL Action Plan, 2020(PDF, 10MB)
- Popes Head Creek Sediment TMDL Action Plan, 2020(PDF, 9MB)
- Accotink Creek Fecal Coliform TMDL Action Plan, 2020 (Revised Feb 2022)(PDF, 14MB)
- Difficult Run Sediment TMDL Action Plan, 2020(PDF, 9MB)
- Difficult Run E. coli TMDL Action Plan, 2020 (Revised Feb 2022)(PDF, 6MB)
- Occoquan River E. coli TMDL Action Plan, 2020 (Revised Feb 2022)(PDF, 11MB)
Additional Information
View the document from NVRC with information and FAQs on stream restoration projects(PDF, 4MB).
Report Illicit Discharge
What is Illicit Discharge?
Any discharge to a storm drain system or waterway that is not composed entirely of stormwater.
Examples:
If you are aware of any discharges into storm sewers, city streams or even on roads that appear to be of a chemical nature, including oil or any hazardous substances that should not be allowed into the city streams, please report using Fairfax City Resolve:
Report Illicit Discharge
Documents for Download
The City of Fairfax has developed written procedures for the Illicit Discharge Detection & Elimination Program. These procedures outline the City’s means and methods to screen stormwater outfalls on an annual basis to proactively identify and address illicit discharges.
City of Fairfax Illicit Discharge Detection & Elimination (IDDE) Procedures(PDF, 1MB)
Please send additional comments and questions about the City’s MS4 permit or stormwater program, including the MS4 Program Plan, to Satoshi.Eto@fairfaxva.gov.