Chesapeake Bay

Overview of the Chesapeake Bay, including why it is important, challenges to water quality, the Bay Program role and structure, and past agreements to clean up the Bay.

Page updated on Jul 30, 2020 at 3:05 PM

Chesapeake Bay Satellite This unique estuary is the largest in the nation and third largest in the world. Its 64,000-square-mile watershed encompasses parts of six states – Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia – and the District of Columbia. In the Chesapeake Bay watershed there are more than 100,000 streams and rivers that eventually flow into the Bay. Everyone in the Bay watershed lives within a few minutes of one of these streams and rivers, which are like pipelines from our communities to the Bay. The Bay and its watershed have remarkable ecological, economic, recreational, historic, and cultural value to the City of Alexandria and the region.

What Issues Affect the Chesapeake Bay?

Clean, healthy water is essential to the health of the plants and animals that live in the Chesapeake Bay and its rivers.  Healthy water contains a balanced amount of nutrients, normal fluctuations in temperature, and plenty of dissolved oxygen so fish, crabs, and other aquatic life can breathe, and few suspended sediments so underwater plants receive enough sunlight to grow.

Any rain that does not evaporate or soak into the ground, but instead ponds and travels downhill is called stormwater.  When rain falls on hard surfaces like roofs, driveways, parking lots, and streets, stormwater can’t naturally soak into the ground and runs off, creating stormwater runoff.  Runoff from urban, agricultural, and industrial areas can contain nutrients, sediment, and chemicals.  The City of Alexandria has adopted an Environmental Management Ordinance to help protect the Chesapeake Bay from pollution and urban runoff.  The Bay is currently subject to several special state and federal regulations; the most important of which is the Chesapeake Bay Total Maximum Daily Load (TMDL).

The City is committed to protecting local streams, the Potomac River, and the Chesapeake Bay and will continue to search out innovative ways to meet the requirements of the Chesapeake Bay TMDL requirements.

Please visit the EPA Chesapeake Bay TMDL website to learn more about the Chesapeake Bay TMDL, including fact sheets, frequently asked questions, and video clips of recorded presentations.

Please visit the Virginia Department of Environmental Quality's Chesapeake Bay TMDL website to learn more about the Virginia WIP process. 

Bay Cleanup Mandates

What does the City Need to Do to Meet the Chesapeake Bay Cleanup Mandates?

The City’s TMDL pollution reduction requirement has been incorporated into the City’s 5-year MS4 permit, which includes the specific pollution reduction requirements that must be met in order to comply with the Bay TMDL.  In order to meet the requirements of the Bay TMDL, the City will have three full five-year MS4 permit cycles to implement the required reductions (Phase I: 2013-2018; Phase II: 2018-2023; and Phase III: 2023-2028).  Please visit the the Stormwater Infrastructure Projects page to learn about ongoing projects the City is working on to meet these cleanup mandates.   

The table below shows the overall amounts of each pollutant, the required reductions, and the equivalent area that will need to be treated to meet these reductions.

Estimated Chesapeake Bay TMDL Pollutant Reduction Requirements (2013-2028)

Pollutant Load Reductions Pollutant Total (lbs/yr) Approximate Equivalent Acres Treated

2009 Pollutant Loads

97,810 7,172 4,704,400 --

Phase I

5%  380  50  43,100  120 – 300

Phase II

35% 2,670  352  301,700  660

Phase III

60% 4,560  603  517,200 1,440
Total Pollutant Reductions Required 100% 7,597 1,004 861,937 2,220 – 2,400

Chesapeake Bay TMDL Action Plan

The City completed a Chesapeake Bay TMDL Action Plan that details the means and methods to meet the Phase I (5%) target reductions for nitrogen, phosphorus and sediment from stormwater runoff that must be implemented no later than the end of the current 5-year MS4 permit period (June 30, 2018). The Draft Chesapeake Bay TMDL Phase I (5%) Action Plan was posted for public comment during June 2015.  The comment-response table and the final Chesapeake Bay TMDL 5% Action Plan can be found below.

The Final Chesapeake Bay TMDL Phase 2 (40%) Action Plan is posted below. Send questions about the plan to or mail to:

Transportation and Environmental Services

Stormwater Management Division

Attn:  Chesapeake Bay TMDL Action Plan

2900-B Business Center Drive

Alexandria, VA 22314

Water Quality Management Supplement & Eco-City Alexandria Environmental Action Plan 

Environmental Action Plan 2030

On January 13, 2001, the City Council adopted the  Water Quality Management Supplement to the Master Plan. The Northern Virginia Region Commission (NVRC), in close collaboration with Alexandria’s Department of Transportation and Environmental Services, prepared the document.  The Water Quality Management Supplement emphasizes Alexandria’s water and habitat resources; focuses on water quality impacts, and directs the City, through specific initiatives, to preserve our existing resources and reclaim and better manage our watersheds. 

The City’s first-ever of its kind  Eco-City Action Plan contains numerous targets and goals related to protecting and enhancing water quality, while the City’s Stormwater Program (mandated by the Clean Water Act and Virginia Administrative Code) seeks to control the discharge of pollutants by managing urban stormwater runoff.