"Efforts to reduce pollution of the Chesapeake Bay are starting to pay off, a major new study says, finding that despite weather-driven ups and downs, the 'dead zone' that stresses fish and shellfish every summer has actually shrunk, on average, in recent years."
"Researchers at the Johns Hopkins University and the University of Maryland Center for Environmental Science teased from 60 years' worth of water-quality measurements what they described as one of the first clear signs of progress in the costly 27-year-old campaign to clean up the bay.
The study, published in the current issue of the scientific journal Estuaries and Coasts, appears to explain away recent research finding no real improvement in the 'dead zone,' where oxygen levels in the bay drop so low each summer that fish and shellfish struggle to survive. The oxygen gets sucked out of the water by the breakdown of massive algae blooms that grow every spring, fed by sewage, farm and urban runoff and air pollution.
In fact, the dead zone that formed early this past summer was the largest ever, scientists say, stretching from above the Bay Bridge to the Potomac River."