Nutrient and Sediment Load Trends

SAV is dependent on good water quality conditions to recover, expand and thrive. Studies show that management actions to reduce nutrient and sediment loads, particularly those made under the Chesapeake Bay TMDL, have resulted in a gradual but significant recovery of the Bay’s SAV. However, continued and expanded nutrient reductions are necessary to reach the goals of the SAV Outcome and mitigate the impacts of climate change.

During 2021, average river flow into the Bay measured 54.8 billion gallons per day, a 9% increase from the 1985-2021 mean. The corresponding pollutant loads entering the Bay in 2021 were all below the 1985-2021 mean, but increased from 2020 (up 16% for nitrogen, 38% for phosphorus and 19% for sediment). Despite this slight increase from 2020 to 2021, nutrient loads into the Bay were significantly less than recent peaks and allowed for a modest recovery of SAV following the catastrophic loss of SAV acreage in 2019.

Public Engagement

The public perception of underwater grasses as a nuisance must be transformed if our restoration and protection efforts are to succeed. Effective communication could better engage this audience.

Legislative Engagement

Laws and regulations meant to protect underwater grasses are essential to their preservation.

Partner Coordination

Small-scale efforts to restore underwater grasses would benefit from partner coordination and collaborative community engagement. Large-scale restoration activities led by federal agencies that are not specific to submerged aquatic vegetation would benefit from the inclusion of SAV.


Efforts to monitor and restore underwater grasses cannot be sustained without continued support from funders.

Scientific and Technical Understanding

Efforts to monitor existing underwater grass beds through the annual aerial survey and the work of partner organizations and individual volunteers are critical to our work to protect and restore underwater grass beds. This work will also benefit from a better understanding of the potential impacts of climate change, the most successful methods of underwater grass restoration and the economic value of the ecosystem services healthy underwater grass beds provide.

Flora, Fauna and Habitat Condition

Invasive species (e.g., plants, animals, bacteria) could impact the recovery of underwater grass beds in some locations. Poor water clarity will also impact underwater grass recovery, although underwater grass restoration should also lead to water clarity improvements.