Draft Chesapeake Bay Total Maximum Daily Load, TMDL

The U.S. Environmental Protection Agency has released a draft Chesapeake Bay Total Maximum Daily Load (TMDL), designed to restore the Chesapeake Bay and its network of streams, creeks and rivers. The draft TMDL sets limits on the amount of nitrogen, phosphorus and sediment pollution discharged into the Bay and each of its tributaries by different types of pollution sources. It is designed to meet water quality standards that reflect a scientific assessment of the pollution reductions necessary to restore the health of the Bay ecosystem. The draft TMDL calls for 25% reductions in nitrogen and phosphorus and at least a 16% reduction in sediment. These reductions would be achieved by a combination of federal and state actions. The TMDL is designed to ensure that all pollution control measures to fully restore the Bay and its tidal rivers are in place by 2025, with 60% of the actions completed by 2017. The final TMDL will be established December 31.

On July 1, 2010, EPA set draft Bay-wide limits for nitrogen and phosphorus at 187.4 million and 12.5 million pounds per year, respectively, and on Aug. 13 set a range of allowable sediment pollution levels at between 6.1 and 6.7 billion pounds per year. These Bay-wide pollution limits were further divided by jurisdiction and major river basin based on modeling tools, monitoring data, peer-reviewed science, and close interaction with state partners.

The release of the draft TMDL begins a 45-day public comment period that will include 18 public meetings in all six watershed states (Virginia, Maryland, Pennsylvania, Delaware, New York and West Virginia) and the District of Columbia.

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