Public Works and Environmental Services

CONTACT INFORMATION: Our administrative offices are open 8 a.m. – 4:30 p.m., Mon - Fri
703-324-5500 TTY 711
12000 Government Center Parkway
Suite 449, Fairfax, Va 22035
Joni Calmbacher
Director, Stormwater Planning

Municipal Separate Storm Sewer System (MS4) Permit

outfallFairfax County's Municipal Separate Storm Sewer System (MS4) permit requires the county to prevent the discharge of pollutants (often called "non-point source" pollutants) such as engine oil, fertilizer, pet waste and trash from the stormwater management system into waterways to the maximum extent practicable. The permit also prohibits non-stormwater discharges into the storm drainage system, such as from sanitary sewer connections or illegal dumping. It also requires storm event monitoring and assessment of the effectiveness of stormwater controls being used in the county. Annual reports submitted to the Virginia Department of Environmental Quality (DEQ) summarize the efforts of government agencies, non-profit agencies and private organizations in managing stormwater runoff and limiting non-point source pollution to the maximum extent practicable

Activities and collective efforts in support of the mission of effective stormwater control include:

For more information about the county's MS4 permit, please contact the Stormwater Planning Division, 703-324-5500, TTY 711.


Fairfax County's MS4 permit is mandated by the Clean Water Act and by Environmental Protection Agency stormwater regulations. The Virginia Department of Environmental Quality administers MS4 permits as part of the Virginia Stormwater Management Program permit program. The permit covers the jurisdictional land area of Fairfax County, excluding the Towns of Clifton, Vienna, and Herndon; the Cities of Fairfax and Falls Church; Fort Belvoir; Dulles International Airport; and the Virginia Department of Transportation's road system.

The maximum amount of a pollutant a waterbody can receive while still meeting water quality standards is referred to as the Total Maximum Daily Load (TMDL). The TMDL is a comprehensive pollution diet for an impaired waterway. While DEQ develops the TMDLs, the county’s MS4 permit requires the development of an action plan to describe the process that will be used to achieve specific pollutant reductions through a stormwater management program.


In 2018, Fairfax County, other Northern Virginia localities, organizations, and community groups assisted DEQ with the development of the Salt Management Strategy to reduce the amount of salt entering our waterways. The county is working with the Metropolitan Washington Council of Government (MWCOG) and Northern Virginia Regional Commission (NVRC) to develop educational materials regarding salt application and management. A summary of the collaborative effort can be found at the following link: The Salt Management Strategy will help Fairfax County to develop a chloride TMDL action plan for Accotink Creek as part of the county’s next MS4 permit. For additional information on salt, please visit the Winter Salt Smart - Outreach & Education | Metropolitan Washington Council of Governments webpage.


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