Municipal Separate Storm Sewer System (MS4) Permit

Alexandria’s Municipal Separate Storm Sewer System (MS4) permit requires the City to prevent the discharge of pollutants into our streams and waterbodies.
Page updated on May 8, 2025 at 4:12 PM
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The federal Clean Water Act of 1970 outlines the NPDES stormwater requirements which are implemented by the Commonwealth of Virginia through the Virginia Pollution Discharge Elimination System (VPDES). The City of Alexandria operates under a VPDES permit associated with the underground stormwater conveyance system which is known as our Municipal Separate Storm Sewer System (MS4) permit. 

About Stormwater Management

The City has long been proactive in its efforts to control stormwater pollution. During the development of Alexandria's Stormwater Management Plan, the City engaged in an extensive assessment of existing stormwater management options, ordinances, and programming and evaluated them against National Pollutant Discharge Elimination System (NPDES) compliance requirements. The City has incorporated these elements into its current stormwater management program.

Controlling Stormwater Pollution

Alexandria has been pro-active in controlling pollution in stormwater runoff for many years. The City’s Soil Erosion and Sediment Control Ordinance actually predates Virginia law and regulations.

Article XIII of the City Zoning Ordinance contains the provisions of both the Virginia Chesapeake Bay Preservation Act and the Virginia Stormwater Management Act, making the City’s developer best management practices (BMP)* program one of the most rigorous ones in the state. Over 1,000 acres of the City have been placed under developer-constructed BMP control since the ordinance was passed in 1992. 

Alexandria has also taken the lead in Northern Virginia in the development and employment of BMPs, which meet the needs of the "Ultra-Urban Environment" (a term that was coined by our staff in 1991). For several years, the City’s Alexandria Supplement to the Northern Virginia BMP Handbook was the only reference available on treating stormwater pollution in heavily built-up areas, and the City has sold hundreds of copies to jurisdictions all over the U.S. and as far distant as Australia and New Zealand. Of the over 535 BMPs installed within the City, most are either intermittent sand filters or bioretention filters.  New state regulations for development require design to meet state criteria.

Working with information provided by the U.S. Environmental Protection Agency, City staff has also published a Best Management Practices Manual for Automotive Related Industries. Compliance with the manual is required of all such businesses that require a Special Use Permit (SUP) by placing appropriate conditions on their SUPs.

* A term used to describe measures to prevent or remove pollution from stormwater runoff. Facilities to remove pollution from runoff, such as wet ponds, detention facilities, infiltration facilities, sand filters, and "bioretention facilities" are known as "structural BMPs." 

Program Recognition

The City of Alexandria's Phase II MS4 Program is recognized by the Water Environment Federation's (WEF) National Municipal Stormwater and Green Infrastructure Awards Program. Visit  WEF's MS4 Awards for more information on the awards program. 

2024 Recognition

Phase II Overall Winner

2022 Recognitions

Gold recognition for Innovation
Silver recognition for Program Management

2021 Recognitions

Phase II Innovation Winner
Silver recognition for Program Management
Gold recognition for Innovation

2020 Recognitions

Phase II Program Management Winner
Silver recognition for Innovation
Gold recognition for Program Management

2019 Recognitions

Phase II Overall Winner
Silver recognition for Innovation
Gold recognition for Program Management

2018 Recognitions

Phase II Winner in Innovation and Overall Highest Score
Silver recognition for Innovation
Gold recognition for Program Management

2017 Recognitions

Phase II Winner in Program Management
Gold recognition for Innovation
Gold recognition for Program Management

2015 Recognitions

Phase II Winner for Innovation
Gold recognition for Program Management
Gold recognition for Innovation

MS4 General Permit and Stormwater Program Plan

Per the Municipal Separate Storm Sewer System (MS4) Coverage Letter and Permit effective November 2023 - October 2028 issued under the Virginia Pollution Discharge Elimination System (VPDES) regulations, the City is required to control stormwater pollution to the maximum extent practicable and to develop a MS4 Program Plan. Under previous permit cycles, the City’s initial plan was developed in 2003 and was revised in subsequent years. The permit contains Six Minimum Control Measures (MCMs) and requirements pertaining to total maximum daily loads (TMDL). 

  • MCM 1: Public Education and Outreach
  • MCM 2: Public Involvement and Participation
  • MCM 3: Illicit Discharge Detection and Elimination
  • MCM 4: Construction Site Stormwater Runoff Control
  • MCM 5: Post-Construction Stormwater Management for New Development and Development on Prior Developed Lands
  • MCM 6: Pollution Prevention and Good Housekeeping for Facilities Owned or Operated by the Permittee within the MS4

The City has developed appropriate and effective Best Management Practices (BMP) to control stormwater pollution to the maximum extent practicable.

The 2023-2028 MS4 Program Plan (updated May 8, 2025) details how the City is addressing the special condition related to the Chesapeake Bay requirements and the MCMs, with an overview provided below. The MS4 Program Plan is updated to reflect the new permit requirements. If you would like to provide input on the MS4 Program Plan or have questions related to the plan, please email MS4ProgramPlan@alexandriava.gov.    

MS4 Annual Reports

Under the MS4 permit regulations, the City is required to submit an annual report to the Virginia Department of Environmental Quality (DEQ). The report provides details of the pollution control measures the City performs as part of the MS4 Program to meet or exceed the control measures (MCMs) of the MS4 permit. The City is required to keep all annual reports online for the current permit. 

2023 - 2028 Permit Cycle

The 2018-2023 MS4 Phase II General Permit included the requirement to separately report on the status of the Chesapeake Bay Total Maximum Daily Load (TMDL) Implementation Annual Status Report.

2018 - 2023 Permit Cycle

2013 - 2018 Permit Cycle

Public Education and Outreach

The City strives to educate and inform the public on the importance of our local waterways, watersheds, and stormwater related issues.

Signs have been placed throughout the City along roadways at major stream crossings to inform the public on the names of local streams and their associated watershed.  A bilingual “no dumping” message is included on  Storm Drain Markers placed on inlets and storm drains throughout the City to prevent the dumping of trash, oil, dog waste, etc. into the drain.

City staff is available for presentations and other educational outreach opportunities for community groups, school age children, and adults.  If you are interested in stormwater education and outreach opportunities call the Stormwater Management Division at 703.746.6499. 

Public Involvement and Participation

You can make a difference in the health of local streams and waterways by reducing pollution, getting involved in local events, and reporting pollution problems or concerns. Stormwater flows into our streams with little or no treatment to remove pollutants.  Therefore, pollution prevention is critical to the health of our streams.  There are simple steps you can take around your home or business that will have a positive impact on the health of the waterways in Alexandria.

Your involvement is the key to a successful stormwater management program. There are many ways citizens can get involved: 

If you have questions or comments, please contact the Stormwater Management Division at 703-746-6499. 

Illicit Discharge Detection and Elimination

Because the storm sewer system is not treated, only stormwater is allowed in the storm sewer system.  An illicit (also called illegal) discharge is any discharge to the storm sewer system that is not entirely stormwater.  There are some exceptions, like groundwater, that are allowed under the MS4 permit.

Non-stormwater discharges to the storm sewer system are usually due to illegal dumping or illegal connections to the storm sewer system.  Please visit the illegal discharges page to learn more about our streams and what you can do to help. 

If you have any concerns about illicit or illegal discharges originating from improper disposal of items, spills, land disturbing activities, or other potential stormwater pollution concerns,  or if you suspect a problem or notice something suspicious (water that is an unusual color, is cloudy, and/or has a strong smell) please contact the Stormwater Management Division at 703-746-6499 or use Contact Us to submit your concern.    

Construction Site Stormwater Runoff Control

Controlling sediment and debris at construction sites is crucial to protecting the environment, mitigating flooding by keeping this material out of our streams and the storm drain system, and ensuring safer travel by keeping mud out of the streets. 

The City's efforts to control stormwater runoff from construction sites are derived from the State's Erosion & Sediment Control Program and Chesapeake Bay Preservation Act.  The City requires any construction project that disturbs 2,500 square feet or more to have an Erosion and Sediment Control Plan.  Additionally, the Virginia Department of Environmental Quality (DEQ) and the City Stormwater Management Program (VSMP) requires the project to have a Stormwater Pollution Prevention Plan (SWPPP) related to the General Permit for Discharges from Construction Activities.  Once the SWPPP is prepared, a registration statement for coverage under the VSMP Construction General Permit must be submitted to the City.  The links below can help get you started: 

For more information on Erosion and Sediment Control at construction sites, contact the Construction and Inspection Division at 703-746-4035. 

Post-Construction Stormwater Management Regulations

Post-construction runoff control is required in areas that are part of the development or redevelopment process.  The City has long required that development and redevelopment projects implement stormwater facility Best Management Practices (BMPs) to minimize the pollutants and runoff to the City's streams.  

Ongoing maintenance of BMPs is required to ensure that they continue to function as designed.  Failure to properly maintain BMPs can result in fines of up to $32,500 per day per violation.  After a development is complete, the responsibility for maintenance is passed on to the owners of the development, such as a homeowners association, through the BMP Maintenance agreement.  It is very important that property owners understand their obligations for the maintenance and inspection of BMPs.

The City can help BMP owners / operators understand their maintenance obligations and can provide technical guidance for inspecting and maintaining BMPs.  The links below can help get you started: 

For more information, contact the Stormwater Management Division at 703-746-6499. 

Pollution Prevention for Municipal Activities

The City also evaluates its own operations to minimize stormwater pollution and protect water quality.  This includes performing assessments of City facilities and providing pollution prevention and good housekeeping training for relevant City employees to ensure good practices are used on City construction and maintenance projects.  In addition, the City requires contractors working for the City to implement pollution prevention and good housekeeping measures on City projects.  The City has developed Stormwater Pollution Prevention Plans (SWPPP) for its Transportation and Environmental Services operations facilities.

For more information, contact the Stormwater Management Division at 703-746-6499. 

TMDL Action Plans

The City is currently operating under three Total Maximum Daily Load (TMDL) action plans to help keep our waterways clean and healthy. To learn more about these action plans, please visit the corresponding webpages linked below.

Chesapeake Bay TMDL Action Plan

Bacteria TMDLs for Hunting Creek, Cameron Run, Holmes Run, and Four Mile Run

PCB TMDL for Tidal Portions of the Potomac and Anacostia Rivers