New Study Finds Chesapeake Bay “Dead Zone” Shrinking

A November 7 JHU Gazette article discusses the findings of a recent study by researchers from Johns Hopkins University and the University of Maryland Center for Environmental Science.  The study, which was published in the November issue of Estuaries and Coasts [subscription required], reviewed 60 years of water-quality data and found that the annual oxygen “dead zones” that form in the Chesapeake Bay have been shrinking for several decades.  The study attributes the improvement on efforts to reduce nutrient run-off into the Bay.

The team found that the size of mid- to late-summer oxygen-starved “dead zones,” where plants and water animals cannot live, leveled off in deep channels of the bay during the 1980s and has been declining ever since. The timing is key because in the 1980s a concerted effort to cut nutrient pollution in the Chesapeake Bay was initiated through the multistate-federal Chesapeake Bay Program. The goal was to restore the water quality and health of the bay.

“I was really excited by these results because they point to improvement in the health of the Chesapeake Bay,” said lead author Rebecca R. Murphy, a doctoral student in the Department of Geography and Environmental Engineering at Johns Hopkins. “We now have evidence that cutting back on the nutrient pollutants pouring into the bay can make a difference. I think that’s really significant.”

Don Boesch, president of the University of Maryland Center for Environmental Science, agreed. “This study shows that our regional efforts to limit nutrient pollution may be producing results,” he said. “Continuing nutrient reduction remains critically important for achieving bay restoration goals.”  …

Another part of the study looked at a trend that has troubled some bay watchers. In recent years, Chesapeake researchers have seen an early summer spike in dead zones. They feared that keeping more nutrients out of the bay was not improving its health. But the new study found that the early summer jump was influenced not by the runoff of pollutants but by climate forces.

“Rebecca discovered that the increase in these early summer dead zones is because of changes in climate forces like wind, sea levels and the salinity of the water. It was not because the efforts to keep pollutants out of the bay were ineffective,” said co-author William P. Ball, a professor of environmental engineering in the Whiting School of Engineering at Johns Hopkins and Murphy’s doctoral adviser.

“We believe,” Ball added, “that without those efforts to rein in the pollutants, the dead zone conditions in June and early July would have been even worse.”

A November 7 Baltimore Sun editorial found the study’s findings encouraging and the stressed benefits of a healthy Bay.  The editorial also cited the importance of the federal Chesapeake Bay Total Maximum Daily Load (TMDL) program in ongoing nutrient reduction efforts and urged that the numerous challenges facing the program should be resisted.

Yet [the TMDL] campaign is in peril, and Congress is its greatest threat. Last week, it came under attack in a hearing held by a subcommittee of the House Agriculture Committee by representatives who claim it would be too costly and that the science behind it is faulty.  … 

Nor is this the only line of attack against the program. Other Republicans in the House would like to rewrite the Clean Water Act to reduce the EPA’s regulatory authority. A lawsuit filed by the American Farm Bureau could upend the effort as well.

Make no mistake, it wouldn’t take all that much to halt the EPA program in its tracks and reverse whatever modest improvements have taken place. There are any number of influential groups fighting hard against tougher pollution standards — from counties that would have to invest in more storm water controls to poultry companies that don’t want to be held accountable for the manure produced by their chickens. All would love to see the program delayed, weakened or killed entirely.

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