Size of Chesapeake ‘dead zone’ average in 2021, researchers say

Every year, researchers measure the size of the “dead zone” in the Chesapeake Bay. That’s the area of the watershed where aquatic life can’t survive due to a lack of oxygen.

Last year, the size of the dead zone was the second smallest recorded since 1985.

This year, the Chesapeake Bay Program partners found the size of the dead zone to be “average.”

Beth McGee, the Chesapeake Bay Foundation’s director of science and agricultural policy, likened the finding to a letter grade. “Although a C in a class might be passing, in this case, a C is not good news,” McGee said.

The dead zone forms when excess nutrients, such as nitrogen and phosphorous, enter waterways through polluted runoff.

The effects of the dead zone are clearly seen in terms of seafood harvested from the bay.

“The only way it affects humans is by affecting the things that we like to catch,” McGee said.

She explained that different forms of aquatic life are affected differently.

“If you’re an animal that can’t move like an oyster at the bottom of the bay, you’ll die,” she said. “If you’re an animal that’s swimming and able to move around, it just means that you’re going to be stressed” and more susceptible to disease.

“I think one of the alarming things that was in their report is that climate change is making things worse,” McGee said.

The partners that make up the Chesapeake Bay Program include the Maryland Department of Natural Resources and the Virginia Department of Environmental Quality, as well as federal agencies, 10 academic institutions and dozens of scientists.

Program partners monitored conditions in the bay between May and October. They found that along with being larger than last year, the conditions that created the dead zone this year lasted nearly 90% longer than those recorded in the past 36 years.

Weather conditions factor into the size and duration of the dead zone, and the report states that “due to calm winds, increased precipitation and warm temperatures throughout the late summer of 2021, conditions were perfect for the dead zone to grow larger” than during the same time in previous years.

Maryland data can be found here. Virginia data can be found here. And you can find tips to help keep the bay healthy on the Chesapeake Bay Program’s website.

Kate Ryan

As a member of the award-winning WTOP News, Kate is focused on state and local government. Her focus has always been on how decisions made in a council chamber or state house affect your house. She's also covered breaking news, education and more.

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