One year after the Chesapeake Bay’s health grade hit a 22-year high, its report card performance has dropped back down. Researchers are hoping it’s a one-year hiccup within a long-term improving trend.
The University of Maryland’s Center for Environmental Science (UMCES) released its 19th annual Chesapeake Bay and Watershed Report Card Tuesday. It measures the cleanliness of the Bay and the ecological, economic, and societal state of its watershed. With 2025 marking an important deadline for cleanup efforts, this data gives a snapshot of where the Bay stands and and highlights the need for continued improvement.
The Chesapeake Bay received an overall score of C (50%). That’s five points lower than last year, but indicates a long-term upswing. The watershed received a C+ (57%), with a good score for ecology and moderate scores for economy and society.
Although this year’s data shows a short-term decline, it’s been slowly improving since the 1980s. “We think extreme weather may have had some impact on the scores this year,” said Dr. Heath Kelsey, Director of UMCES Integration and Application Network. Last year was the hottest year on record, with extreme rain patterns contributing to pollution. Prolonged summer droughts, punctuated by runoff events, can cause pollutants to accumulate in waterways.
Most Bay health indicators show long-term improvement: scores are higher for dissolved oxygen, aquatic grasses, total phosphorus, and total nitrogen. Chlorophyll a and water clarity scores have declined, with water clarity receiving an F (18%). This issue remains “mysterious,” according to Bill Dennison, Vice President for Science Application at UMCES. Bay scientists are still investigating the cause of this persistent murkiness, which isn’t fully explained by phytoplankton or sediment.
Water clarity impacts other indicators, too: with recent high temperatures, aquatic grasses are in danger of burning out. Clear water enables them to handle the heat, but cloudy water traps heat and prevents photosynthesis. “The synergistic effect of turbid water and high temperature is a death knell to these plants,” said Dennison. “Water clarity is something we really need to work on because it will build more resilience for the Bay.”
Six regions in the Bay have shown improvement: the Elizabeth, James, and Patapsco and Back rivers, the upper western shore, the upper Bay, and the lower Bay. The lower Bay had the highest grade (B) probably due to its tidal exchange with the Atlantic Ocean and the health of its James River tributary in Virginia. The upper Eastern Shore was the only region with a declining score. UMCES will partner with the Delmarva Land and Litter Collaborative later this month to investigate the reasons for that downward trend.
UMCES also wants to replicate the success of their positive data: for example, a resurgence of aquatic grasses in the upper Bay is helping improve water quality. “We’re really interested in these ecological tipping points,” said Dennison, “places where we could provide that little extra push that gets us positive feedback that will create a longer-term sustainable Bay.”
Alongside the Chesapeake Bay Report Card, the Watershed Report Card provides a more holistic approach to health. “The water is downstream, but everything we do connects,” said Rebecca Flora, Maryland Secretary of Planning. For an overall score of C+, it considered three factors of the watershed: Ecology (scoring a B-), Economy (C+), and Society (C-). The Economy category indicated a high score for job growth but a low score for income equality. The Society indicator for heat vulnerability also scored low. With recent high temperatures, watershed communities are at risk for heat stress. To mitigate this risk, they need more trees. “Trees are a natural cooling agent, provide habitats, and produce carbon dioxide,” said Dennison. “There are so many reasons we need to plant trees—urban and rural.”
As UMCES celebrates its centennial this year, they’ve also created a 1925 report card to reflect 100 years of Chesapeake science. According to old data, the 1925 Bay received a B, indicating minimal pollution and thriving animal life. Since then, extreme rainfall, droughts, high temperatures, and increased pollution have made it trickier to maintain Bay health.
“Cleaning up the Bay is like trying to walk up a down escalator,” said Maryland Senator Chris Van Hollen. “UMCES has been climbing up that escalator for 100 years, and the Bay is better because of it.” This year’s report card shows a path forward for environmentalists and policy-makers as they plan beyond 2025 milestones.
