Chesapeake Bay TMDL Action Plan

In 2010, the EPA established a comprehensive pollution diet for the Chesapeake Bay called the Chesapeake Bay Total Maximum Daily Load (TMDL). The TMDL included accountability measures to restore clean water in the Bay and local streams and rivers.

The Chesapeake Bay TMDL requires Arlington and other MS4 Stormwater Permit holders to achieve specific nutrient and sediment reductions through local stormwater management programs. Arlington must reach these reduction targets in three Stormwater Permit cycles:

• 5% of the overall nutrient and sediment reduction by the end of the 2013–2018* permit cycle 
• 40% of the overall nutrient and sediment reduction by the end of the 2021–2026 permit cycle 
• 100% of the overall nutrient and sediment reduction by the end of the 2026–2031 permit cycle 

* Note that there was a three-year delay between the end of the first permit cycle (2013-2018) and the issuance of the second permit.  

The County’s overall strategy to meet the TMDL requirements includes stream resilience projects and watershed retrofits as two key methods to meet the pollution reduction requirements. In addition, stringent regulation of the stormwater runoff from development/redevelopment will continue to achieve incremental and cumulative reductions in stormwater pollutants.

2021-2026 Chesapeake Bay TMDL Action Plan

The County’s 2021-2026 Stormwater Permit requires a detailed plan to meet the 40% reduction requirements. This plan, called the Chesapeake Bay TMDL Action Plan, outlines the specific projects and programs implemented to meet these goals. The actions included in the plan derive from the County’s adopted Stormwater Permit. The draft Chesapeake Bay TMDL Action Plan was available for a required public comment period from April 15 - 30, 2022, recognizing that the scope of the actions included in the plan are defined by the County’s Stormwater Permit.

View the 2021-2026 Chesapeake Bay TMDL Action Plan.(PDF, 918KB)

2013-2018 Chesapeake Bay TMDL Action Plan 

The County’s 2013-2018 Stormwater Permit required that the County meet 5% of overall reduction requirements. The 2013-2018 TMDL Action Plan was approved by the Virginia Department of Environmental Quality (DEQ) in September, 2015. The County met its 5% reduction goals. 

Public comment was received on the plan and summarized in Appendix G.

View the 2013-2018 Chesapeake Bay TMDL Action Plan.

2013-2018 Chesapeake Bay TMDL Action Plan Appendices:

• Appendix A – MS4 Service Area
• Appendix B – BMP Accounting
• Appendix C – Watershed Retrofit Accounting
• Appendix D – Large Project Computations
• Appendix E – Large Project Maps
• Appendix F – Stream Restoration Project Documentation
• Appendix G – Summary of Public Comment 

Summary of Arlington’s 2013-2018 Chesapeake Bay TMDL Action Plan:

• The implementation strategy outlined in the document is consistent with the overall strategy outlined in the adopted Stormwater Master Plan.
• With projects and programs implemented since 2006 (the crediting baseline established by DEQ), Arlington County has already met the 5% pollution reduction requirement for this permit cycle (including FY15 progress).
  • These projects include two stream restoration projects in the Donaldson Run watershed, extensive retrofits at the Arlington County Trades Center, and pollutant reductions achieved through redevelopment activity.
  • The pollutant reductions computed using the DEQ guidance methodology are: nitrogen—5.3%; phosphorus—17%; and sediment—13%.
  • The estimated cost to date of the projects implemented is $3 million.
• Two additional stream restoration projects and multiple watershed retrofit projects (including the large Ballston Pond project) are planned for implementation by the end of the permit cycle (2018)
• The Action Plan document explains that any reductions achieved beyond the 5% requirement will be credited to the next permit cycle (and into the third permit cycle in the case of phosphorus). It is important to exceed the 5% requirement during this permit cycle to stay on pace to meet the full requirement in three permit cycles—rather than following the progressively steep implementation curve (5%, 35%, 60%).
• It should also be noted that EPA will be evaluating overall Bay restoration progress in 2017, and it is anticipated that there may be changes to the pollutant reduction requirements for local governments across Virginia and the Bay watershed. More reduction may be required.