The Chesapeake Bay watershed spans over 64,000 square miles within six states, covering parts of New York, Pennsylvania, Delaware, Virginia, West Virginia, nearly all of Maryland, and the entire District of Columbia. If you live in the watershed, all the water that washes off the roofs, lawns, sidewalks, and streets in your neighborhood drains into one of the 100,000 streams and rivers that eventually flow into the Bay. These streams and rivers form "sub-watersheds," and you can learn more about the one you live in by entering your zip code at the EPA’s "Surf Your Watershed" web page.
The Chesapeake Bay forms the largest estuary in the United States. As such, it provides critical habitats and breeding grounds for thousands of species of fish, birds, mammals, and other wildlife. The wetlands that border the bay filter chemical pollutants from runoff, prevent erosion, and serve as a buffer against floods.
The biggest threat to life in the Chesapeake Bay over the last century has been pollution from a variety of sources (industrial waste, land development, agriculture, vehicle spills, trash). But more and more, the changing climate creates new challenges for the Chesapeake that threaten to alter the entire ecology of the Bay.
The Bay’s average water temperature increased 1.4 to 2 degrees Fahrenheit from the 1950s to 2000. As the water warms, it expands, raising the sea level of the Bay. At the same time, land development has contributed to erosion of the Bay’s shoreline, exacerbating the problem of sea level rise. All told, the water level of the Bay has risen a foot over the last century. These rising waters caused the disappearance of Sharps Island and the abandonment of four other islands, leading to the loss of entire towns. The Chesapeake is predicted to rise another 17 to 28 inches over the next century.
What should we expect as the sea level of the Chesapeake Bay continues to rise? The U.S. Environmental Protection Agency, together with three other national agencies, studied this issue in depth and produced a 790-page report entitled "Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region" in January of 2009. Among their findings:
• Coastal lands and barrier islands will erode at an accelerated pace.
• Wetlands that rim the Chesapeake along the Maryland and Virginia coasts, which are already being submerged, will disappear more rapidly as the sea level rises. If the sea level rises 20 inches in the next century and no new measures are taken to protect them, most of the Chesapeake’s wetlands will be lost.
• Wetlands provide a buffer against storm surges from hurricanes; so as hurricanes increase in frequency and intensity due to the warming ocean, the disappearance of this buffer will increase the potential for flooding from hurricanes.
• Loss of tidal marshes and estuaries, which comprise a unique habitat for diverse species, would threaten numerous species of fish, waterfowl, reptiles, amphibians, crustaceans, mollusks, insects, and plants.
• Wetlands provide a filter for pollution entering the Bay. Loss of wetlands would compromise the quality of water in the Bay, further threatening the many varieties of animals and plants that live there.
The report recommends several ways in which we can prepare for sea-level rise. Actions that address near-term risks include building up wetlands that are in danger of being lost, raising dikes, and elevating homes above the predicted flood level. Other actions could be taken now, at little cost, to address future sea-level rise. These include: limiting development in areas bordering wetlands to allow the wetlands to migrate inland as the Bay rises; building new homes farther back from the water and elevating them by a few feet (as flood protection); and designing new coastal drainage systems to handle the predicted increase in water flow.
Maryland has begun to address the rise of the Bay in several ways. In a pilot project, the U.S. Fish and Wildlife Service is using sediment dredged from boat channels to rebuild wetlands at Blackwater National Wildlife Refuge. In Baltimore City, where Hurricane Isabel flooded streets and homes in the Fells Point historic district in 2003, regulations governing development are being reviewed with the goal of extending elevation requirements to areas that will become vulnerable to flooding as the Bay rises. Calvert County, on the western shore of the Chesapeake, prohibits construction of sea walls along estuaries, a policy aimed at preserving its unique cliffs that would also enable the migration of wetlands inland. And the Chesapeake Bay Critical Area Protection Act, passed in 1984 to help reverse the deterioration of the Chesapeake Bay (and revised in 2002 to include Atlantic coastal bays), helps address the rise in Bay level by discouraging the building of sea walls, which prevent wetland migration.
Although we can’t put a complete stop to erosion and rising seas, we can work to limit these changes and to protect the more than 3,600 species of plants and animals that depend on the Bay. This will require planning for migration of wetlands to areas that are currently above sea level, as well as the enforcement of existing laws aimed at preserving life on the Bay.
If you want to be part of the solution, contact the Chesapeake Bay Foundation, which has been dedicated to protecting and restoring the Chesapeake Bay for over 40 years, or get involved in your local watershed association – I’ve included a couple of examples in the “Links” section below.
Elsewhere on the Web:
The Chesapeake Bay Program
A regional partnership of people and organizations, ranging from federal and state agencies to local governments to non-profits and academic institutions, that has led the restoration of the Chesapeake Bay since 1983.
The Chesapeake Bay Foundation
A nonprofit organization dedicated to restoring and protecting the Chesapeake Bay and its tributary rivers.
A nonprofit organization dedicated to preserving and conserving Virginia wetlands.
Jones Falls Watershed Association
A grassroots organization dedicated to protecting and restoring the 58-square-mile Jones Falls Watershed in Baltimore City and Baltimore County.
Carol Berkower is a mathematician and molecular biologist living in Baltimore.
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