Cleaning Up the Bay: Big Science, Big Plan
Two of the leading sources of excess nutrients entering the Bay are farms, like this one on the Eastern Shore, and wastewater treatment plants, like the Back River treatment plant near Baltimore, shown here. Credit: Skip Brown (left), Jane Thomas (right).

TALKING ABOUT THE CHESAPEAKE BAY, America's largest estuary, inevitably seems to require talking big. H.L. Mencken portrayed the Bay as a "great protein factory." And, before him, the Algonquins named it "Chesepiooc," meaning "great water."

Superlatives also apply easily to the ambitious project currently underway to clean up this vast estuary, tributary by tributary. Mandated in 2010 by the U.S. Environmental Protection Agency under a section of the Clean Water Act, the cleanup push will take place over the next decade and beyond. Federal and state officials will use a tool called the Chesapeake Bay Total Maximum Daily Load, or TMDL, to require major cuts to the excess nutrients and sediments streaming from the region's land and skies into the Bay. The limits set by TMDLs have been dubbed the Chesapeake's "pollution diet."

The enormous scale of this mandatory and expensive cleanup, involving the six states that make up the Bay's 64,000-square-mile watershed, makes the project the largest and most complex of its kind in U.S. history. Below, we offer a basic overview of the plan — its goals, history, and what, exactly, is a "TMDL."

Elsewhere in this issue of Chesapeake Quarterly, we examine a scientific tool that was used to construct the cleanup strategy (see A Model Plan). The tool, computer modeling, allows experts to predict the behavior of complex systems like the Bay. Those predictions, in turn, enabled the cleanup plan's authors to set targets for improving water quality over such a big area of land and water. But because models are based on assumptions and field observations, the portrait of nature they offer is never perfect. The Chesapeake Bay Model has drawn public scrutiny for that reason and because so much money is riding on whether its predictions are accurate enough.

Another article, A Garden of Opportunities, explores one way in which this abstract set of model equations and data could literally come home and take root in your front lawn. The cleanup plan relies partly on reducing the flow of nitrogen-laden stormwater from urban and suburban areas, like parking lots and lawns, into the Bay's tributaries. Scientists are studying a variety of methods to do that, including the landscaping technique known as rain gardens.

What is a "TMDL," and what does it have to do with the Bay's restoration?

TMDL means Total Maximum Daily Load. It's a legal term for the maximum amount of a pollutant that can be added to a water body — like a stream, a river, or the Bay — without violating federal and state government rules for water quality-. Restric-tions of those pollutants are aimed at making water bodies "fishable and swimmable." In the Chesapeake Bay, the U.S. Environmental Protection Agency led an effort, completed in 2010, to set TMDLs that would limit the flow of nitrogen, phosphorus, and sediment into the Bay and its tidal tributaries. The agency and its partners now require communities in the Chesapeake region to reduce levels of those nutrients and sediments by the year 2025.

What's the problem that needs fixing?

Too much nitrogen and phosphorus entering the estuary have increased the frequency of algae blooms in its waters. These blooms block sunlight from reaching and sustaining underwater grasses, which are important for maintaining a healthy ecology. When the algae decompose, they create "dead zones" in large parts of the Bay, areas where dissolved oxygen levels are too low to sustain fish and shellfish. Excess sediment also blocks sunlight, further degrading water quality. The result is a loss of habitat for aquatic species.

Why is this effort under way now?

States surrounding the Chesapeake began working together in 1983 to improve water quality, and yet scientists say that loads of nutrients and sediments are still too high today. The current levels exceed what researchers have estimated are the maximum for a healthy, sustainable ecosystem. Many parts of the estuary are still officially listed as degraded under federal standards for water quality. The states set goals for reducing nutrients but did not meet two major deadlines, in 2000 and 2010, for doing so. The latest cleanup plan is partly in response to lawsuits filed against the federal government — by environmental groups in Virginia and the District of Columbia — that accused the EPA of failing to enforce the Clean Water Act. Further momentum for change came in 2009 when President Obama issued an executive order directing federal agencies to speed up the Bay's restoration.

What does the cleanup plan require?

The TMDL plan calls for reducing approximately 25 percent of the nitrogen and phosphorus entering the Bay and 20 percent of the sediment. States were required to write documents called Watershed Implementation Plans, or WIPs, describing pollution control measures to be taken locally to accomplish those reductions. All measures are to be in place by the year 2025. States may need to take several steps to reduce the pollutants at the source, including upgrading sewage treatment plants, minimizing stormwater discharges, and reducing nutrients flowing from farms. Nutrient loads from stormwater and farm runoff are more difficult to measure accurately than those from the discharge of pipes at "point sources" like sewage plants. The actions cover the Bay's entire drainage area or "watershed," which includes 17 million people and 64,000 square miles in Maryland, Virginia, the District of Columbia, Delaware, Pennsylvania, New York, and West Virginia.

What if communities don't meet the reduction goals?

For the first time in the Bay's multi-year restoration effort, the EPA has said it will take enforcement actions that have teeth. For example, it could force a sewage treatment plant to install additional equipment to further reduce nutrient discharges in order to renew its operating permit. Or the federal government could withhold grants for water quality improve-ment projects. Every two years until 2025, the EPA will review each state's progress toward meeting its pollution-diet goals and take corrective action if needed. A major review is scheduled for 2017.

How much will the restoration cost? Who will pay? And will the cost be worth it?

Estimating the price tag and benefits of a Baywide cleanup has proven to be a complicated and uncertain accounting exercise. The state of Maryland alone has estimated nearly $15 billion in combined costs through 2025 for measures like upgrading municipal stormwater disposal systems (the single costliest measure) and building structures on farms to control manure runoff. State officials say that the grand total could fall as the cleanup strategy is refined and market-based incentives to lower costs are developed. Upgrades to sewage treatment plants will be passed on through utility bills; Maryland, for example, has already doubled its so-called "flush tax," a state surcharge that pays for upgrades, from $30 to $60 on average per household annually. Advocates of the cleanup plan say that, in return, it will yield economic gains from resuscitating the state's commercial fisheries, growing its aquaculture industry, and bolstering recreation and tourism businesses. And then there's the satisfaction and enjoyment that all area residents could take in helping to restore one of America's major natural resources.

How can I help the restoration?

Although many cleanup measures will be the responsibility of municipal utility officials- and farmers, you can take additional steps that could help meet the cleanup targets. They include driving your car less, because auto emissions are another source of nitrogen entering the Bay's waters. Avoid using lawn fertilizer or apply it only once a year, in the fall. Install rain gardens and other home landscaping to keep rainwater on your property so it won't flow into streams and rivers. See For More Information for a list of resources for rain gardens.

— Jeffrey Brainard

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