Maryland reports rise in Chesapeake Bay sea grass expansion

Good news for the Chesapeake Bay. Maryland's Department of Natural Resources (DNR) reported Tuesday that the bay's underwater grasses expanded almost 13% in 2025.  

In Maryland's portion of the bay, underwater grass coverage expanded from 36,799 acres in 2024 to 41,419 acres in 2025, the DNR said in a statement.   

"More underwater grass means more habitat for blue crabs and fish, cleaner water, and a more resilient Chesapeake Bay," said DNR Secretary Josh Kurtz. 

The acreage progress recorded in 2025 represents roughly 36% of Maryland's 114,065-acre restoration target. 

The annual underwater grass survey is carried out by the Virginia Institute of Marine Science (VIMS), which maps submerged aquatic vegetation, or SAV, throughout the Chesapeake Bay and its tidal tributaries. 

The SAV beds are among the bay's most valuable shallow water habitats. This is because they provide food, shelter, and nursery grounds for fish, blue crabs, waterfowl, and other wildlife. They improve water quality by absorbing nutrients and trapping sediments, adding oxygen to the water through photosynthesis, stabilizing sediments at the bottom of the bay and reducing shoreline erosion.    

"What is especially encouraging about 2025 is that the gains were not confined to one place," said Brooke Landry, SAV program chief for Maryland DNR, and chair of the Chesapeake Bay Program SAV Workgroup.   

"This year's increase is welcome progress, but it also reinforces the work ahead," Kurtz said. "We need to keep reducing pollution, protecting existing underwater grass beds, and restoring the shallow-water habitats that allow these plants and the Bay life that depends on them to thrive." 

The underwater grass beds also store carbon and act as a barrier to coastal acidification, which is important to Maryland's shellfish industry. 

Tidal Fresh: Freshwater grasses continue recovery 

• Maryland's tidal fresh and low-salinity waters gained a combined 1,059 acres of SAV in 2025. Seven different Maryland river or Bay segments met or exceeded their SAV restoration goals last year. These included: 
• Northern Chesapeake Bay segment 1 -- 102% of its 754-acre goal 
• Northeast River – 179% of its 89-acre goal  
• Upper Chester River – 531% of its 1-acre goal  
• Upper Sassafras River – 275% of its 95-acre goal  
• Bush River – 158% of its 350-acre goal  
• Upper Gunpowder River – 107% of its 572-acre goal 
• Back River – 712% of its 30-acre goal 

Two additional freshwater segments were close to their restoration goals: 

• Northern Chesapeake Bay segment 2, which includes the expansive Susquehanna Flats SAV bed, reached 91% of its 12,149-acre SAV goal.  
• Mattawoman Creek, a Potomac River tributary, maintained 85% of its 792-acre goal, despite a 200-acre loss of SAV in the creek. 

"These communities are dynamic: when light, salinity and other growing conditions align, species such as widgeon grass can spread quickly," Landry said. "The flip side is that the same beds can decline just as quickly when conditions deteriorate, which is why long-term monitoring, sustained water-quality improvements, and protection of existing habitat remain so important." 

Maryland's DNR said its partners continue working to protect existing SAV beds, improve water quality and clarity, restore underwater grass and monitor the progress long-term to better understand how habitats are changing. 

Keeping an eye on other rivers 

Even though the Bay saw record progress in saltier waters, the progress made overshaows the decline of several other rivers. 

According to a statement from the Chesapeake Bay Foundation,  some rivers in Marylnd and Virginia have seen a dramatic drop in underwater grassess. Those that have seen drops include the Potomac, Patapsco, Gunpowder, Rappahannock, and James rivers. 

"Underwater grass gains across the Bay are welcome news, but Maryland's rivers tell a more complicated story. Declines in places like the Patapsco, Gunpowder, and Potomac show the pressure from polluted runoff and increasingly intense rainstorms," said Chesapeake Bay Foundation Maryland Coastal Scientist Julie Luecke in a statement.

The Chesapeake Bay Foundation said in a statement that although the growth of under water grass almost reache  the Cheasapeake Watershed  agreement's 2030 goal of 90,000 acres, work still remains to meet the long term goal of 196,6000 acres by 2040.

"Increased underwater grass coverage is a clear sign of how the Bay is healing. While there's plenty to celebrate with more grasses in saltier parts of the Bay, the declines in many rivers, including the Rappahannock, reveal that significant work remains. Polluted runoff from sources like development and agriculture remains a big threat to underwater grasses, and this is exacerbated by rising temperatures and more intense storms fueled by climate change. State and federal leaders have their work cut out for them to meet their commitments of 196,600 acres of grasses by 2040. Now is the time to double down on efforts to reduce pollution to the Bay and its rivers and streams," said Chesapeake Bay Foundation Virginia Senior Scientist Joe Wood.