The Chesapeake Bay will have a smaller “dead zone,” or an area of little to no oxygen, this year, researchers say.
When excess nutrients, such as from fertilizers, enter the water, there is an algae bloom. Not only does algae block the sunlight, but too much of it also means a lot of decomposition, which takes away much of the oxygen in the water. With less sunlight and oxygen, plants and animals struggle to survive in this “dead zone.”
Researchers from the Chesapeake Bay Program, the University of Maryland Center for Environmental Science, University of Michigan and U.S. Geological Survey predict that the “dead zone” in the Chesapeake Bay will be 9% lower than average and the amount of water with no oxygen will be 5% lower than the average. This is due to less rainfall and less nutrient run-off this spring.
“Dissolved oxygen levels are a key indicator of Bay health as sufficient oxygen is needed to support our iconic Cheseapaek species such as oysters, crabs and fin fish,” said Bruce Michael, the Director of Resource Assessment Service of Maryland Department of Natural Resources. “The forecast brings attention to our continued need to implement our nutrient reduction strategies.”
Excess nutrients can come from wastewater treatment plants, runoff from lawn fertilizers in backyards and livestock manure from farms, and air pollution. Nitrogen and phosphorus are the two most concerning nutrient pollutants that frequently reach the Bay. Heavy rainfall can generate strong river flows, which helps carry nutrient pollution into the Bay.
Ways to decrease nutrient pollution include planting trees and shrubs near rivers to prevent pollution from entering the water. Planting trees in urban or suburban areas can also trap air pollution and prevent stormwater from reaching the Bay.
This year, the Chesapeake Bay nitrogen pollution levels were 17%, which is slightly below average.
“The river flows and nutrient loads were closer to average conditions in spring 2020. The more normal spring flows, along with the nutrient reduction efforts of the Chesapeake Bay Program, should result in smaller amounts of hypoxia [deficiency in amount of oxygen] this summer compared to 2018 and 2019, when near-record levels of spring rains washed more nutrients into the Bay,” said Scott Phillips, co-chair of the Scientific Technical Assessment and Reporting Workgroup in the Chesapeake Bay Program.
Some environmental advocates say that this slightly below average “dead zone” is not something to be excited about. Large algae blooms and low-oxygen environments will still continue.
“The good news is that dead zones are shrinking over time, but more must be done to accelerate progress,” said Lisa Feldt, the vice president of the Chesapeake Bay Foundation.
States like Pennsylvania and New York are not keeping up with their pollution reduction goals, she said.
“This is why CBF, and the Attorney General from Virginia, Maryland, the District of Columbia and Delaware have filed notices of intent to sue EPA,” Feldt said. “If EPA does not hold Pennsylvania and New York accountable, restoration efforts will fail, and the Bay and its rivers and streams may never be clean.”