Scientists Predict Bigger Bay "Dead Zone" This Summer

Just as Bay scientists were heralding the disappearance of the Bay's "dead zone"- a low-oxygen area that can kill fish and aquatic life- word comes that this summer's hypoxic zone will be larger than usual.

The National Oceanic and Atmopsheric Administration (NOAA) says the dead zone will be about 1.89 cubic miles, nearly the volume of 3.2 million Olympic-sized swimming pools.

Measurements for the Bay’s dead zone go back to 1950, and the 30-year mean maximum dead zone volume is 1.74 cubic miles.

“Despite this year’s forecast, we’ve made great strides in reducing nutrient pollution from various sources entering the Chesapeake Bay, and we are starting to see positive long-term signs,” said Rob Magnien, director of NOAA’s Center for Sponsored Coastal Ocean Research. “However, more work needs to be done to address nonpoint nutrient pollution from farms and other developed lands, to make the Bay cleaner for its communities and economic interests.”

The low-oxygen and oxygen-free zones are caused by excess nutrient pollution, thanks to agriculture and wastewater. The runoff stimulates an algae overgrowth, and the algae sucks oxygen out of the Bay, depriving marine life of the oxygen they need.

One section of the dead zone, known as the "anoxic" portion, contains no oxygen at all. It is predicted to be slightly above average as well. Scientists attribute that to high nutrient loading from the Susquehanna River.

Rainfall amounts are a big player in determining the amount of runoff in a given year. Because New York and Pennsylvania had a lot of rain this spring, the streamflow from the Susquehanna into the Bay has been higher than normal.

The Bay outlook is based on models developed by NOAA-sponsored researchers at the University of Maryland Center for Environmental Scienceoffsite link and the University of Michiganoffsite link. They rely on nutrient loading estimates from the U.S. Geological Survey. Throughout the year, researchers measure oxygen and nutrient levels as part of the Chesapeake Bay Monitoring Program, run by the Maryland Department of Natural Resourcesoffsite link and the Virginia Department of Environmental Quality. This year’s findings will be released in the fall.

Megan Viviano