June 30, 2021 — The Chesapeake Bay’s “dead zone,” the oxygen-starved blob of water that waxes and wanes each summer, is forecast to be smaller than average for a second consecutive year.
A consortium of research institutions announced June 23 that it expects the volume of this year’s dead zone to be 14% lower than average. In 2020, the zone was smaller than 80% of those monitored since surveying began in 1985.
The size of the summer dead zone is driven largely by how much excess nutrients flow off lawns and agricultural fields into the Bay during the preceding January to May, researchers say. Those nutrients — nitrogen and phosphorus — fuel explosive algae growth, triggering a chemical reaction that robs the water of oxygen as it dies back. The area is dubbed a “dead zone” because of the lack of life found within it.
This year, those first five months were slightly drier than usual, causing river flows entering the Bay to be 13% below average. As a result, the Chesapeake received 19% less nitrogen pollution compared with the long-term average at monitoring stations along nine major tributaries.
Efforts to curb nutrient pollution in the Bay’s 64,000-square-mile watershed also appear to have played a role in shrinking this year’s dead zone, scientists say. The U.S. Environmental Protection Agency has joined with Delaware, the District of Columbia, Maryland, New York, Pennsylvania, Virginia and West Virginia to implement a “pollution diet” for the Bay and its tributaries by 2025.