Chesapeake Bay TMDL


In 1998, significant portions of Chesapeake Bay and its tidal tributaries within Virginia were identified as not meeting water quality standards and listed as impaired. Areas of the Bay and tidal rivers within Maryland, Delaware and the District of Columbia are also on the federally approved list of impaired waters. The main pollutants causing these impairments are nitrogen, phosphorus, and sediment. Despite significant efforts from the Chesapeake Bay Program, the water quality goals under the Clean Water Act have yet to be met.

Because these Bay waters remained on the impaired waters list, EPA required that a Total Maximum Daily Load (TMDL) be developed. A TMDL is the maximum limit of a given pollutant that can be discharged and still maintain the health of the receiving water body, in this case, the Chesapeake Bay. EPA issued the Bay TMDL on December 29, 2010. It was based, in part, on the Watershed Implementation Plans (WIP) developed by the Bay watershed states and the District of Columbia.

The Chesapeake Bay TMDL addresses all segments of the Bay and its tidal tributaries that are on the impaired waters list. As with all TMDLs, a maximum aggregate watershed pollutant loading necessary to achieve the Chesapeake Bay’s water quality standards has been identified. This aggregate watershed loading is divided among the Bay states and their major tributary basins, as well as by major source categories (wastewater, urban storm water, septic, agriculture, air deposition). The TMDL is available on EPA's Chesapeake Bay TMDL website.

Virginia submitted its Phase I Watershed Implementation Plan (WIP) in November 2010, and EPA accepted that plan and included it in the Chesapeake Bay TMDL with minor modifications.

In November 2011, Virginia requested locality specific input into the Phase II WIP development process. The City of Williamsburg responded to the request on February 1, 2012 and included a study done in cooperation with other Hampton Roads localities.

The draft Phase II Watershed Implementation Plan (WIP II) was submitted to EPA in December 2011, and the Phase II WIP was submitted on March 30, 2012. Additional information can be found on the Virginia DEQ’s website for the Chesapeake Bay TMDL

To comply with the Chesapeake Bay TMDL, additional requirements are included in the City of Williamsburg’s Municipal Separate Storm Sewer (MS4) permit. The City is required to implement additional measures to reduce nitrogen, phosphorus, and sediment loadings in three stages over the next three permit cycles (15 years).

On June 29, 2015, the City of Williamsburg published a Chesapeake Bay TMDL Action Plan. The plan details specific treatments to meet the City's initial 5% pollutant reduction goals for the first permit cycle by June 30, 2018. The plan was open for Public Comment until July 29, 2015. No comments were received that required revisions to the plan so the final plan was submitted to the Virginia DEQ on September 30, 2015.  Minor revisions based upon DEQ's review were made and the final Chesapeake Bay TMDL Action Plan was published on December 16, 2015.

Written comments or questions on the Chesapeake Bay TMDL Action Plan may be dropped off or mailed to the Department of Public Works at 401 Lafayette Street, Williamsburg, VA 23188 or e-mailed to

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