Underwater grasses cover more of the Chesapeake Bay and its tidal tributaries this year compared to last, though Maryland has only reached about one-third of its restoration goal.
Submerged aquatic vegetation, or SAV, throughout the Chesapeake Bay increased from 83,252 acres in 2024 to 89,385 acres in 2025, a 7% increase, according to an annual underwater grass survey conducted by the Virginia Institute of Marine Science.
In Maryland’s share of the Bay, that coverage grew nearly 13% from 36,799 acres in 2024 to 41,419 acres in 2025.
Although the increase is significant progress, the 2025 acreage represents about 36% of Maryland’s restoration target of 114,065 acres of underwater grass coverage.
“More underwater grass means more habitat for blue crabs and fish, cleaner water, and a more resilient Chesapeake Bay,” said Josh Kurtz, secretary of the Maryland Department of Natural Resources. “This year’s increase is welcome progress, but it also reinforces the work ahead. 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 increase follows underwater grass losses in Maryland’s freshwater areas in 2023, as well as declines among the moderately salt-tolerant mid-Bay community in 2024.
Expansion or contraction of grass beds from year to year can be the result of nutrient and sediment runoff, algal blooms, storms, temperature, and changing salinity.
Maryland’s portion of the Chesapeake Bay added more than 4,600 acres of habitats, with underwater grass beds providing food, shelter, and nursery grounds for fish, blue crabs, waterfowl and other wildlife.
They also improve water quality by absorbing nutrients, stabilizing bottom sediments, trapping suspended sediment, adding oxygen to the water through photosynthesis, storing carbon, and reducing shoreline erosion.
The growth of submerged aquatic vegetation was recorded in various parts of the Bay.
“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. “We saw expansion in both freshwater and moderately salty parts of Maryland’s Bay waters.”
Seven Maryland river or Bay segments reached or surpassed their SAV restoration goals last year, including Northern Chesapeake Bay segment 1, North East River, Upper Chester River, Upper Sassafras River, Bush River, Upper Gunpowder River, and Back River.
Two freshwater segments — Northern Chesapeake Bay segment 2 (including the Susquehanna Flats SAV bed) and Mattawoman Creek (a Potomac River tributary) — were close to their restoration goals.
No mid-Bay river segments reached their SAV restoration goals, but the region saw an expansion of Bay grasses.
Maryland saw some of its largest gains in moderately salty waters of the mid-Bay, where SAV increased 3,560 acres (about 17%).
Freshwater areas support vegetation like wild celery, water stargrass, several naiads, pondweeds, and other species.
Meanwhile, widgeon grass and sago pondweed account for much of the underwater grasses in Maryland’s mid-Bay.
“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.”
