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 Jul 30, 2020 at 2:43 PM

About Stormwater Management 

Little Hunting Creek Park

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." 

Municipal Separate Storm Sewer System (MS4) Program

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. 

City's Stormwater Program Recognized by Water Environment Federation

Since 2015, the Phase II MS4 Program has been recognized by the Water Environment Federation's (WEF) National Municipal Stormwater and Green Infrastructure Awards Program. In 2018, the MS4 Program was winner of the Phase II "Overall Highest Score" and "Innovation" categories. The City's MS4 Program is featured in the Spring 2019 edition of Stormwater Management magazine. Visit  WEF's MS4 Awards for more information on the awards program.  More information on the City's MS4 Program is provided below.

MS4 General Permit and Stormwater Program Plan
Per the Municipal Separate Storm Sewer System (MS4) General Permit and Coverage Letter effective November 2018 - October 2023 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 2008, 2013, and 2019.  The permit contains Six Minimum Control Measures (MCMs):

  • 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 (BMPs) to control stormwater pollution to the maximum extent practicable. The 2018-2023 MS4 Program Plan (main body) Appendices A to C Appendices D to H details how the City is addressing the special condition related to the Chesapeake Bay requirements and the MCMs, with an overview provided below.  If you would like to provide input on the MS4 Program Plan or have questions related to the plan, please email    

Local TMDL Action Plans

As required under the MS4 permit, the City updated the local TMDL action plans for bacteria and PCBs in 2020. These updates are incorporated into the 2018-2023 MS4 Program Plan, above. Please see the City's TMDL webpage for more information on TMDLs. 

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. 

The following annual report covers the July 1, 2018 to June 30, 2019 reporting period.

Alexandria MS4 Annual Report 2018-2019

The following annual report covers the July 1, 2017 to June 30, 2018 reporting period.

Alexandria MS4 PY5 Annual Report 2017-2018

The following annual report covers the July 1, 2016 to June 30, 2017 reporting period.

Alexandria MS4 PY4 Annual Report 2016-2017

The following annual report covers the July 1, 2015 to June 30, 2016 reporting period.

Alexandria MS4 PY3 Annual Report 2015-2016

The following annual report covers the July 1, 2014 to June 30, 2015 reporting period.

Alexandria MS4 PY2 Annual Report 2014-2015 

The following annual report covers the July 1, 2013 to June 30, 2014 reporting period .

Alexandria MS4 PY1 Annual Report Main Body
Alexandria MS4 PY1 Annual Report AppendixA 
Alexandria MS4 PY1 Annual Report AppendixB 
Alexandria MS4 PY1 Annual Report AppendixC 
Alexandria MS4 PY1 Annual Report AppendixD 
Alexandria MS4 PY1 Annual Report AppendixE
Alexandria MS4 PY1 Annual Report AppendixF

Chesapeake Bay Watershed ImagePublic 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   Illicit Discharge
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.    

Silt FenceConstruction 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. 

Reading SignPost-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.