The Chesapeake Bay’s health has taken a downturn, according to a new report card, with the estuary relegated from a “C+” to a “C” as climate extremes and runaway pollution limit restoration efforts.

The annual scorecard, produced by the University of Maryland Center for Environmental Science (UMCES), evaluates the state of the bay and its watershed using ecological, social and economic indicators. The 2025 report lays out a mixed picture: Some long-term trends showed improvement but the effects of record heat, erratic rainfall and persistent nutrient pollution from fertilizer runoff undercut recent gains.

Overall, the bay’s health score dropped from 55 percent in 2024 to 50 percent this year. Eleven of 15 monitored regions registered declines. The report described the deterioration as “unfortunate but not surprising,” attributing much of the regression to the hottest year on record in 2024, combined with inconsistent precipitation patterns alternating between drought and intense storms.

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“While parts of the watershed experienced drought, brief but intense downpours also caused runoff into Bay waters,” the report stated. “These downpours can cause water to flow over the ground rather than soak into it, increasing the fertilizer, dirt, and debris carried into waterways.”

Indicators measuring dissolved oxygen—a critical factor for marine life—remained strong at 90 percent, but water clarity nosedived to a score of just 18 percent. Chlorophyll-a levels, which are used to track algal blooms fueled by excess nutrients, also scored poorly at 22 percent.

The score for aquatic grasses, a key ingredient for fish and crabs, fell to 38 percent, signaling stress on habitat. Total nitrogen and phosphorus levels were scored at 56 percent and 80 percent respectively, showing some improvement but reflecting persistent challenges in nutrient management.

Despite this year’s setback, the report stated that the bay’s overall condition is still better than historical lows in the 1980s. Management and restoration efforts by states and localities have made a difference, UMCES noted, including upgrades to wastewater treatment plants.

Watershed Fares Better Than Bay

The broader Chesapeake Bay watershed—encompassing six states and Washington, D.C.—earned a “C+” grade.

Some regions scored better than others. The Upper James River watershed in Virginia received the highest score at 61 percent, while the Choptank watershed on Maryland’s Eastern Shore ranked lowest at 42 percent. The Delmarva Peninsula, a hotspot of agricultural runoff, continues to see significant challenges in managing nutrient flows into the bay’s tributaries despite targeted efforts.

This year’s report card featured new indicators, such as Temperature Stress and Conductivity, reflecting a growing scientific consensus that climate-related stressors are closely tied with water quality. It identifies increasing salt levels in freshwater systems—known as freshwater salinization—as a key factor that could have far-reaching consequences for both aquatic life and drinking water.

While the UMCES report card is widely considered a good aggregate of bay health, some experts raised concerns that its methodology may obscure critical nuances.

Betsy Nicholas, president of the Potomac Riverkeeper Network, a watchdog group for pollution and clean water enforcement, argued that the scorecard’s reliance on averaging can oversimplify complex regional variations.

“When you’re doing a report card that looks at the big picture, we’re often not understanding the local impacts, which are going to be much more significant for the communities living there,” she said. “When you zoom out to big picture scale, it loses that granularity that’s really helpful in understanding the real scientific and ecological reasons for the issues and problems.”

The need for granular understanding is even greater in the case of the Potomac region, she said, which had one of the lowest rankings in this year’s report card.

She added that threats to communities adjacent to heavily impaired regions, such as the Choptank and Lower Eastern Shore, may not be reflected in a regional “C” grade. On top of that, she said, the report doesn’t evaluate toxic pollution, a problem concentrated in certain areas.

Heath Kelsey, who leads the scorecard project at UMCES, acknowledged the limitations in generalizing a vast, complex ecosystem like the bay into a single grade, but defended the approach as a necessary communication tool.

“We recognize that there’s always more granularity than we can capture in a composite score,” Kelsey said. “But we’re also trying to produce a report that’s accessible and digestible to the public, policymakers and advocates. The alternative is paralysis by complexity. Of course, you can still look at each indicator and category on its own to better understand the specific sector you are interested in.”

He added that ongoing efforts are underway to improve data granularity and participatory monitoring, including collaborations with local communities and nonprofits to refine sub-watershed metrics.

“Having the latest data and assessing the trends is a critical tool for clean water advocates.” — Kristin Reilly, director of the Choose Clean Water Coalition

For Kristin Reilly, director of the Choose Clean Water Coalition, the scorecard serves as both a progress tracker and a warning flag. She pointed to the ongoing need for states within the watershed to fulfill their cleanup obligations under the Chesapeake Bay Program’s pollution reduction goals.

“Having the latest data and assessing the trends is a critical tool for clean water advocates,” Reilly said. “Report cards like these are helpful to see where we are seeing positive returns and where we need to refocus our efforts. Each community surrounding the Chesapeake Bay is unique, and there are no one-size-fits-all answers for pollution challenges.”

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She emphasized that while progress has occurred in areas like wastewater treatment plant upgrades, agriculture—the single largest source of nutrient pollution—remains inadequately addressed across key upstream states.

“We need to address all sources of pollution, but it’s important to thoughtfully consider tactics and work with communities as partners in restoring local water quality,” she said.

The Climate Concern

Scientists broadly agree that the Chesapeake Bay’s restoration effort is entering a new, more volatile phase driven by climate instability.

Extreme rainfall events push enormous sediment and nutrient loads into the bay in short, intense bursts, overwhelming existing filtration systems. Warmer waters stress native fish and shellfish populations, while sea-level rise threatens to inundate wetlands that serve as natural buffers. Meanwhile, salinity from saltwater intrusion and road salt runoff is taking a toll on freshwater ecosystems throughout the watershed.

UMCES scientists noted that nutrient reductions are increasingly being challenged by these climate-related factors. The 2025 report card states: “Water clarity has been declining over time, despite improvements in nutrient pollution. One potential cause is extreme weather, and understanding how storms affect the region will help managers make informed decisions.”

But despite the regression in this year’s scores, experts said the bay’s restoration remains on a positive trajectory, demonstrating long-term resilience.

Kelsey pointed to regional partnerships, updated monitoring tools and new stakeholder engagement models as signs that the restoration community is learning to adjust. “We’re continuously working to improve the categories and the indicators we use within those categories to reflect values and goals of restoration, management and community needs,” he said.

Nicholas agreed that broader inclusion of frontline communities in future scorecard designs would strengthen public trust and policy responsiveness. “The communities that are most impacted need a louder voice at the table,” she said. “That’s where better data and better governance intersect.”

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