Chesapeake Bay underwater grasses reach highest acreage since 2018

Underwater grass coverage in the Chesapeake Bay and its tidal tributaries has reached its highest level since 2018. An annual aerial survey conducted by the Virginia Institute of Marine Science reported a total of 89,385 acres of submerged aquatic vegetation (SAV) in 2025, an increase of 6,134 acres from the previous year.

The expansion was largely driven by growth in higher-salinity waters. The Polyhaline Zone, located near the mouth of the Bay, grew to an estimated 28,142 acres, while the Mesohaline Zone expanded by nearly 15% to approximately 37,879 acres. Researchers attribute this growth, particularly in eelgrass, to improved water clarity in the lower Bay.

In Maryland specifically, grass coverage increased by nearly 13%, rising from 36,799 acres in 2024 to 41,419 acres in 2025. While these gains represent significant progress toward restoration goals, the current acreage remains at approximately 36% of Maryland’s target and about 45% of the Chesapeake Bay Watershed Agreement’s 2030 interim goal of 90,000 acres.