How Volunteers and State Scientists Reseed the Chesapeake Bay: Inside the Push to Restore Underwater Grasses

Overview

Planting underwater grasses in the Chesapeake Bay looks deceptively simple: crews mix millions of tiny, spherical seeds with sand and toss the mixture by hand from boats into carefully chosen areas. But the months of preparation — wading into shallow tributaries to harvest seeds, processing them, selecting donor beds and monitoring results — are what make the work possible.

How seeds are collected

Teams, including state biologists and riverkeeper volunteers, harvest seeds during the plants' summer reproductive period by wading into shallow waters. 'We throw everybody in the water with a wetsuit and a laundry basket and we literally walk around in circles,' says Mark Lewandowski of the Maryland Department of Natural Resources. Harvesters strip seed-bearing tops from the shoots while leaving roots intact so donor beds can recover. One nonprofit, the Arundel Rivers Federation, collected about 7.5 million seeds this past summer.

Processing and planting

After collection, plant material is processed in a "turbulator," a hot-tub–like system that agitates the mixture using air pumped through PVC piping so seeds fall to the bottom and can be separated. Technicians then mix the cleaned seeds with sand and literally toss the sand-seed mix by the handful from small boats into targeted restoration sites — a method that is far faster and less labor-intensive than planting whole plants by hand.

Why submerged aquatic vegetation (SAV) matters

SAV provides critical ecosystem services: it shelters vulnerable species such as molting blue crabs and juvenile striped bass, feeds invertebrates and waterfowl, absorbs excess nutrients that fuel algal blooms and dead zones, traps sediment to slow shoreline erosion, helps stabilize pH and even sequesters carbon.

Goals, challenges and progress

SAV once covered much of the Chesapeake Bay bottom but declined dramatically as development increased nutrient and sediment runoff, blocking the sunlight grasses need. In 2014, bay states pledged to expand SAV to 130,000 acres by 2025. The Virginia Institute of Marine Science's 2024 aerial survey estimated 82,778 acres — well below that target. Heavy rains in 2018 and 2019 caused setbacks, and climate change and continued development have made restoration more difficult.

Under a new multistate agreement expected to be approved by Maryland Gov. Wes Moore and other leaders, parties set an interim goal of 100,000 acres by 2040 and identified 196,600 acres (allocated among the bay's salinity zones) as the acreage needed for a restored Bay.

Partnerships, volunteers and citizen science

State staff are now joined by a growing network of riverkeeper nonprofits and volunteers who provide funding, labor and local knowledge. Riverkeeper groups sometimes hire state staff to carry out plantings in their rivers, and programs like the Chesapeake Bay Program's SAV Watchers train citizen scientists to ground-truth aerial surveys and document species composition from shorelines, kayaks or small boats.

Volunteers helped identify that horned pondweed is more widespread than aerial surveys suggested because it follows a slightly different seasonal schedule. Beyond data, volunteer involvement builds stewardship: many people who help as SAV Watchers or with plantings become personally invested in the health of grasses off their shorelines.

Looking ahead

Managers emphasize that seeding is one piece of a larger strategy that includes protecting existing beds and improving water quality so grasses can grow naturally. Careful donor-bed selection — choosing dense beds that have persisted for several years — helps ensure harvests don’t harm source populations. Restoring seagrass is a multigenerational effort: many riverkeepers hope future generations will experience a Chesapeake once again carpeted with underwater grasses.

'We take a portion of that seed and try to replicate that bed in an area that wouldn't otherwise have the bed,' says riverkeeper Elle Bassett.

Key facts: Arundel Rivers Federation collected roughly 7.5 million seeds in one summer; 2,000 sago pondweed seeds were distributed recently in the Severn River. The 2024 VIMS aerial survey estimated 82,778 acres of SAV, while the new bay agreement sets an interim target of 100,000 acres by 2040 and a restored-bay benchmark of 196,600 acres.