The overall health of Baltimore's harbor is holding steady, according to the 2025 Healthy Harbor Report Card released on Friday. While some areas are improving, others are headed in the wrong direction.

The annual update reports on the water quality and health of Baltimore's Inner Harbor based on data gathered by both Blue Water Baltimore and Waterfront Partnership in 2024.

The harbor earned a "C" for overall ecosystem health, a grade that has held steady in recent years. The report showed both ecological improvements and ongoing vulnerabilities.

Record oxygen levels, but algae concerns remain

Dissolved oxygen levels, a key measure of aquatic health, earned an "A" for the first time in the report's history. 

According to the Waterfront Partnership, improved oxygen levels reflect major infrastructure upgrades and nutrient-reduction efforts across the region.

"Baltimore's Harbor is no longer dismissed as dead water," said Adam Lindquist, vice president of Waterfront Partnership. "We are seeing river otters return, oysters thrive and swimmers reclaim the water through events like Harbor Splash. At the same time, the ongoing pistachio tide is a reminder that our ecosystem remains fragile."

Still, chlorophyll, an indicator of algae blooms, fell to a "D," its lowest mark since 2010. The report said nutrient pollution from stormwater runoff and wastewater continues to fuel algae growth that can block sunlight and deplete oxygen.

"With zero dissolved oxygen, the sulfide-rich anoxic water and green sulfur bacteria from the bottom have replaced the oxygen-producing algae and the bright green pistachio tide has lingered day after day," said Lindquist. 

Harbor conditionally safe for swimming

Routine monitoring found the Inner Harbor met Maryland's standard for safe swimming about 80% of the time, except within 48 hours of rainfall.

Fells Point showed the greatest progress, with water samples meeting Maryland's safety standard 83% of the time in 2024 — up from none in 2011. The Jones Falls River Mouth, once among the most polluted sites, also improved by 60 percentage points over the same period.

After hosting the first public swim in more than 40 years last summer, Waterfront Partnership said it plans to expand opportunities for safe recreation while continuing to monitor water quality.

"Weather doesn't always do it once we humans are messy and we have created a lot of problems, but we are great problem solvers, and our message continues to be clear: Baltimore is an amazing place to be," said ultra-marathon swimmer Katie Pumphrey. "Our Patapsco River and harbor is worth advocating for, and Baltimore is a swimmable city." 

Progress and remaining challenges

The report noted both promise and fragility in the ecosystem. River otters have returned, but a September turnover event caused oxygen levels to drop to zero overnight, triggering a fish kill that left thousands of Atlantic menhaden dead.

Oysters continue to play a key role in water restoration. Since 2013, more than 1.6 million oysters have been cultivated in the harbor. The group's new goal is to grow 5 million more over the next five years.

Meanwhile, the Mr. Trash Wheel family collected 278,000 beverage containers in 2024. To reduce litter, Waterfront Partnership is advocating for a statewide "Bottle Bill" that would incentivize recycling.

"I want to emphasize that a clean and healthy harbor starts with all of us," said Matthew Garbark, the director of the Baltimore City Department of Public Works.

Residents react 

"I'm not a big fan of the smell," said city resident Sonny Antonelli. "You know, it smells like sulfur or eggs or something, but the water looks like a blue tropical paradise. There's a little bit of a plus to it." 

People like Antonelli and his friends live and work near the Inner Harbor and can't help but wonder when the pistachio tide will end. 

"I take the boat to work every day, so it's definitely making the commute pretty awful, having to deal with it," explained resident Austin Cassity. 

Most neighbors said they are used to the smell and it will not stop them from enjoying the festivities of Fells Fest. 

"It's gross, but I guess, at this point, I'm used to it," said Julio Prado. 

"The water looks very pretty, but it doesn't smell great, and so hopefully it won't deter people from coming down here, because I know Fells Fest is huge every year," said Permila Lisperg, a Canton resident.