The Chesapeake Bay is at its healthiest in decades, report finds

Newly released water monitoring in the Chesapeake Bay found that 2025 was the estuary’s healthiest year on record.

That finding comes from an annual report card, released Tuesday by the University of Maryland Center for Environmental Science. The center grades the Chesapeake Bay’s health at 56%, a 6-point bump from the year before and the bay’s highest score in almost 40 years of monitoring.

The percentage translates to a C+ letter grade — the same as the previous record-setting report card from two years ago. That is considered a “moderate” performance.

The assessment relies on water quality sampling across the bay and its tributaries. This year’s report card draws on monitoring conducted last year.

Alexandra Fries, a UMCES program manager who led the new assessment, said federal cuts to environmental programs can be disheartening, but data shows that efforts across the Chesapeake Bay — from small creeks to whole-watershed campaigns — are paying off.

“Our collective efforts are making a difference,” she said.

UMCES scientists are expected to present their findings alongside Maryland and Virginia officials on Tuesday at a George Mason University research center on the Potomac River, south of Washington, D.C.

From year to year, the bay’s health can swing, depending on changes in the climate. The latest grade represents a rebound from a year earlier, when erratic weather and persistent heat helped drive the bay’s water quality back down to a C.

Lately, Maryland has struggled with persistent drought — conditions that can mean less runoff washing pollutants into the bay — and the report cites the decrease in rain as a factor contributing to the score.

Still, Fries said the 6-point improvement is likely too big a swing to be explained just by lack of rain. Some measures of health, such as water clarity and the amount of algae growth, are going in the wrong direction, but long-term trends for dissolved oxygen, underwater grasses and concentrations of nitrogen and phosphorus pollution — the nutrients breeding “dead zones” that stifle underwater life — are all steadily improving across most regions.

Tuesday’s findings come as Maryland leaders have recently celebrated some belated wins for the bay.

The region-wide Chesapeake Bay cleanup missed most of its goals ahead of a much-anticipated 2025 deadline, but Gov. Wes Moore’s administration announced in August that Maryland had nearly fulfilled all of its commitments. Meanwhile, recent surveys show that underwater grasses expanded 13% in Maryland’s portion of the bay last year, while oysters are seeing a steady resurgence.

Federal support for the decades-long bay restoration, meanwhile, remains uncertain. President Donald Trump hasn’t tried to slash funding for the program — as he did in his previous term — but last month he repealed an Obama-era executive order that had long organized the federal response to the bay cleanup.

Virginia’s Lower Bay, where Atlantic Ocean water mixes with the estuary, continues to be substantially healthier than much of the big waters in Maryland. The Lower Bay region scored a B+ in the new report, compared to C grades for the middle and northernmost parts of the bay, much of which falls within Maryland.

Some tributaries, like the Potomac and Patapsco rivers, scored worse.

The Baltimore area’s Patapsco and Back rivers have long ranked at the bottom of Chesapeake Bay tributaries. But water-quality grades in those two rivers have more than doubled since measurements began in 1986.

Alice Volpitta, a water quality watchdog for the group Blue Water Baltimore, said she has seen a few encouraging trends in the Baltimore-area rivers: Fecal bacteria from sewage overflows seems to be abating, and improvements to the Patapsco Wastewater Treatment Plant have corresponded with dropping nitrogen levels in that river.

Still, Volpitta cautioned that other metrics reveal areas of concern: According to Blue Water’s monitoring, phosphorus contamination in the Patapsco and Back rivers is going up, as are average water temperatures.

The most improved region in this year’s assessment was the Upper Western Shore, an area that includes the Gunpowder River in Baltimore County. It jumped from a 43% water quality score in 2024 to 57% last year.

The Gunpowder has seen its share of pollution threats in recent years — including from a proposed landfill expansion and ongoing issues at a large housing development — and Theaux Le Gardeur, the Gunpowder Riverkeeper, said much of this bounce-back may be thanks to low rainfall.

Le Gardeur, a fishing guide, is worried that salt concentrations seem to be increasing in the Gunpowder. And he said he has noticed fewer and fewer species, such as white perch, yellow perch and striped bass, returning to his river to spawn.

A lot of people are encouraged to see scores go up, Le Gardeur said, but there are also troubling signs in the water.

“I’ve got an 11-year-old in Baltimore County Public Schools, and if he came home with a C, I’d be raising my eyebrows,” he said.