MS4 Stormwater Permit


The Virginia Department of Environmental Quality (DEQ) issues permits for the discharge of stormwater into waterways like Four Mile Run and the Potomac River. These permits, called municipal separate storm sewer system (MS4) permits, are good for five years. Arlington’s current MS4 permit (VPDES Permit No. VA 0088579) was issued on July 1, 2021.

Arlington was the first municipality in Virginia to receive an MS4 permit that included quantitative pollution reduction requirements to clean up the Chesapeake Bay. The Chesapeake Bay Total Maximum Daily Load (TMDL), which is commonly referred to as the “bay pollution diet,” requires significant reductions in nutrient and sediment pollution across the bay watershed.

Each MS4 permit is good for five years, and the new permit will be in effect through mid-2026.  During this permit cycle, Arlington is required to achieve a 35 percent reduction of its share of these bay TDML pollutants, in addition to the 5 percent reduction required during the previous 2013-2018 permit term. In the following permit cycle (2026-2031), Arlington will be required to reduce its share of these Bay TDML pollutants by an additional 60 percent.

Supporting Programs

We began preparing for the permit and its more stringent requirements in 2008 with the adoption of the Stormwater Fund. The fund has allowed for the expansion of permit-required watershed management programs. The following programs and projects are among those that are specifically described in the permit:

Arlington Stormwater Pollution Prevention Plans (SWPPPs)

As part of the MS4 permit, Arlington works to prevent pollution on-site at County facilities. Each site or facility has a stormwater pollution prevention plan (SWPPP). The SWPPP includes best practices that keep pollutants safely contained and out of the storm drain network and streams. Only rain in the storm drain!