There’s encouraging news about the health of the Chesapeake Bay: A smaller than average “dead zone” is forecast for summer 2021, for the second year in a row.
Dead zones are areas of tidal rivers in the Chesapeake Bay with low or no oxygen, making it difficult for underwater plants and animals to survive.
“The dead zone for this summer will be below average, which is good,” said Beth McGee, the Chesapeake Bay Foundation’s Director of Science and Agricultural Policy.
This marks the second year in a row that smaller-than-average dead zones were forecast: “Last year, the dead zone was among the best on record, frankly, in terms of the volume,” McGee said.
Researchers with the Chesapeake Bay Program, the University of Maryland Center for Environmental Science, University of Michigan and U.S. Geological Survey based the prediction on reduced river flows into the bay, as well as less nutrient and sediment pollution thanks to recent actions taken across the watershed to improve water quality.
“If you get a lot of rain, you get a lot of runoff, and you get a lot pollution coming into the bay, and that affects the size of the dead zone,” McGee said.
Of particular concern, in creating the dead zone, is excess nutrients flowing into the water. Much comes from nitrogen and phosphorus.
“These are chemicals that are in the fertilizer we use on our lawns,” said McGee.
Too many nutrients in the rivers that feed the bay cause algae to grow, prompting an algal bloom.
“When the algae die and sink to the bottom and decompose, oxygen is used up, and that’s what causes the dead zones,” said McGee.
Of the nine rivers funneling into the bay, McGee said monitoring shows approximately 40% of the nitrogen pollution that causes dead zones comes from the Susquehanna River.
“The majority of the land feeding the Susquehanna is actually in Pennsylvania, and Pennsylvania is the state that’s furthest behind in achieving their pollution reduction goals to restore water quality downstream in the Chesapeake Bay,” McGee said.
The Chesapeake Bay Foundation and the Attorneys General for Virginia, Maryland, the District of Columbia and Delaware are suing the Environmental Protection Agency, saying federal regulators have failed to hold Pennsylvania responsible.
A bay-wide assessment of the 2021 dead zone will be released this fall.