Bay Health Declines

 Chesapeake Bay Mag, Bay Report Card’s C Grade Shows Drop in Health Since Last Year

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. Prolonged droughts followed by runoff events may have contributed to this year’s lower scores.

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.

I take a pretty dim view of these grading systems. They have high annual variability as a result of weather fluctuations, so it's only in the multi-year long run that you can see improvements or declines. As with most people, I judge the Bay health on results that mean something to me. Rockfish (aka Striped Bass) populations have been steadily declining for years. Crabs took a serious turn for the worst this year. The bright spot from a resource point of view, is that the populations of oysters are about a the best they've been since I arrived in 1985.