by Alicia Pimental
July 01, 2010
The U.S. Environmental Protection Agency has proposed draft sediment limits as part of a “pollution diet” the agency is developing to restore the Chesapeake Bay and its local streams, creeks and rivers.
The watershed-wide draft limit of 6.1-6.7 billion pounds of sediment per year is divided among the six watershed states and the District of Columbia, as well as the major river basins. In 2009, an estimated 8.09 billion pounds of sediment flowed to and clouded the waters of the Bay and its tributaries.
Excess sediment suspended in the water is one of the leading causes of the Chesapeake Bay's poor health. The culprits are the tiny clay- and silt-sized fractions of sediment. Because of their small size, clay and silt particles often float throughout the water, rather than settling to the bottom, and can be carried long distances during rainstorms.
When there is too much sediment in the water, the water becomes cloudy and muddy-looking. Cloudy water does not allow sunlight to filter through to bay grasses growing at the bottom of the Bay's shallows. Just like plants on earth, bay grasses need sunlight to grow; without it, these underwater grasses die, which affects the young fish and blue crabs that depend on bay grasses for shelter.
Bay jurisdictions are expected to use the draft allocations as the basis for completing their Watershed Implementation Plans (WIPs), which detail how they will further divide the limits among different sources of pollution and achieve the required reductions. Jurisdictions must provide the first drafts of their WIPs to the EPA by September 1, and final Phase 1 WIPs are due November 29.
“While we all recognize that every jurisdiction within the watershed will have to make very difficult choices to reduce pollution, we also recognize that we must collectively accelerate our efforts if we are going to restore this national treasure as part of our legacy for future generations,” said EPA Regional Administrator Shawn Garvin.
The EPA expects the Bay jurisdictions to have all practices in place to meet their established pollution limits by 2025, with 60 percent of the effort completed by 2017. Progress will be measured using two-year milestones, or short-term goals. The EPA may apply consequences for inadequate plans or failing to meet the milestones.
The EPA will issue a draft Chesapeake Bay Total Maximum Daily Load (TMDL) – the “pollution diet” – on September 24, with a 45-day public comment period immediately following. The final Bay TMDL will be established by December 31.
The EPA proposed draft allocations for nitrogen and phosphorus in July.
For more information about the Chesapeake Bay TMDL, visit www.epa.gov/chesapeakebaytmdl.