University of Maryland environmental scientists give the Chesapeake Bay a C on health report

After two straight years of declines due to record rainfall in 2018, the Chesapeake Bay’s health improved slightly in 2020, according to a report from the University of Maryland’s Center for Environmental Science.

The center’s grade for the estuary ticked up from a C- back to a C. The entire watershed received a B- for the second straight year.


The grade is based on measurements of phosphorous, nitrogen, dissolved oxygen, water clarity and the health of aquatic grasses and bottom-dwellers.

Officials dubbed the data a mixed bag. For instance, the bay’s dissolved oxygen and nitrogen levels improved, but the scores for chlorophyll and phosphorous worsened. Water clarity, too, remains poor.

In this Nov. 19, 2019 file photo, watermen dredge for oysters on the Chesapeake Bay in southern Maryland near Ridge, Md. The health of the Chesapeake Bay is getting a better grade in an annual environmental report card. The University of Maryland Center for Environmental Science on Tuesday, June 22, 2021, gave the health of the nation's largest estuary a C grade for 2020. That's up from a C-minus in 2019.

“We’re making some progress — moderate on the bay, and a little better in terms of the watershed — but we have our work cut out for us,” said Maryland’s Secretary of the Environment Ben Grumbles said during a news conference Tuesday about the report at Sandy Point State Park.

The grades come as a 2025 deadline for bay cleanup speeds ever closer. That deadline — established by the Environmental Protection Agency in 2010 — sets annual maximum levels of nutrients and sediment for the Chesapeake.

“We’re probably not going to hit the mark we want by 2025,” said Bill Dennison, the vice president for science applications at the University of Maryland environmental center, “but I really have always felt like I want to be going in the right direction. That’s the prime, most important thing.”

When all of the 2020 indicators were considered together, seven of the 15 bay regions studied showed strong improvement, while the remaining eight showed no significant change.

The University of Maryland’s center is one of several groups that grade the bay. Earlier this year, the Chesapeake Bay Foundation, a nonprofit that supports bay restoration efforts, gave the bay its second straight D+, due in large part to its declining rockfish population.

But this year’s score from the center didn’t take into account the population of rockfish, also known as striped bass, because of insufficient data from 2020. The Virginia Institute of Marine Science, which traditionally collects data on 1 to 3-year-old rockfish for the center’s report, changed its equipment, forcing a recalibration of the data that hasn’t been completed yet, said Alexandra Fries, a program manager with UMCES.


Because that data traditionally forms a third of the center’s fishery score, that entire category was excluded from this year’s report. It usually also includes data on blue crabs and bay anchovy.

For the second year, the center also graded the entire Chesapeake Bay watershed, which encompasses the land surrounding the bay and its tributaries, like the Susquehanna and the Potomac rivers, in Maryland, Pennsylvania, Virginia and New York.

It did so this year with extra indicators focused on land conservation, civic engagement around bay issues, access to green space and vulnerability to high temperatures.

When those scores were tallied, together with figures focused on water and soil health, the West Branch of the Susquehanna River in Pennsylvania came out on top with an A-. The York River of Virginia area received the lowest score, with a C. All of the Maryland tributary areas received a B or B-, with the exception of the Choptank River region, which received a C+.

The center plans to add more new indicators next year, including measurements focused on environmental justice and economic well-being in communities surrounding the bay.

Dennison said the new indicators allow for a more holistic perspective on bay restoration.


“We think that by moving into the watershed with social and economic indicators, we’ll do a better job of forecasting how we can improve the bay,” he said.

This year’s report was a story of highs and lows. For Fries, the phosphorous and nitrogen tallies were promising. There was a gap in monitoring between March and May 2020 as a result of the COVID-19 pandemic, but the phosphorous score worsened only slightly, and the nitrogen score rebounded from 39 out of 100 in 2019 to 64 in 2020. A score of 80 to 100 is considered an A.

“One of the biggest problems I see is water clarity, which we don’t fully understand why it’s so bad,” Fries said.

After sediment runs off into the bay, it can cloud waters, hindering the spread of aquatic vegetation and phytoplankton. The bay’s water clarity score decreased from 10 out of 100 to 8 in 2020.

Dennison said he was encouraged by the center’s studies of freshwater bay grasses, even though the overall score for grasses declined, due to extreme heat events impacting the Lower Bay last summer.

“The most invigorating thing anybody can do is to drive a boat up the Susquehanna flats and take a look at those grass beds,” he said. “The water is crystal clear.”