PHILADELPHIA — The U.S. Environmental Protection Agency (EPA) announced draft sediment limits as the next step in establishing the Watershed Implementation Plans (WIPs) for the Chesapeake Bay Total Maximum Daily Load (TMDL). The TMDL is a rigorous pollution diet for meeting the water quality standards in the Chesapeake Bay and its tidal tributaries, and restoring local rivers and streams throughout the 64,000-square-mile watershed.

The six watershed states and the District of Columbia are expected to use the limits, along with those previously issued for nitrogen and phosphorus, as the basis for completing WIPs detailing how they will further divide these limits among pollution sources, and what practices will be implemented to meet water quality standards.

An EPA analysis indicates the likelihood that measures to control and reduce nutrient pollution as outlined in these WIPs will also significantly reduce sediment runoff, achieving the annual sediment limits.

Too much sediment in the water is a major problem impairing the Chesapeake Bay. Excess floating clay and silt particles cause clouding of the water, and blocking sunlight from reaching underwater grasses. These underwater grasses can’t grow without sunlight, and die, harming young fish, blue crabs, and other aquatic life needing bay grasses for shelter to survive. Underwater grasses are also a critical food source for many of the bay’s key waterfowl species.

The first drafts of the WIPs are due to EPA by Sept. 1. On Sept. 24, EPA plans to issue a draft TMDL and open a 45-day public comment period, including 18 public meetings. The final WIPs are due Nov. 29, and EPA will establish the final bay TMDL by Dec. 31.

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