About this Site

This website brings decades of Chesapeake Bay data to life. Using information related to water quality and the abundance of underwater grasses—also known as submerged aquatic vegetation or SAV—this interactive map tracks changes in Bay health over time. Move through a 30-year timeline to watch fluctuations in water temperature, salinity and turbidity take place alongside changes in grass abundance, as dominant species ebb and flow and grass beds shrink and expand. Or, hover your mouse over the rivers and streams that flow into the Bay to read about the unique stories of underwater grasses that have taken place over time.

Data Sources

This map of the Chesapeake Bay was created using bathymetry data from the National Oceanic and Atmospheric Administration (NOAA). More on that soon!

Data related to water quality—including water temperature, salinity and turbidity—is from the Chesapeake Bay Program Water Quality Database, which documents water quality from 1984 to the present.

Data related to the abundance of submerged aquatic vegetation is from the Virginia Institute of Marine Science (VIMS), whose researchers conduct aerial surveys of the Bay’s grass beds each year.

More Resources

Learn the Issues: Bay Grasses
Learn more about underwater grasses in the Bay: their role as a food source and habitat, the factors that can affect their growth and the ways in which vital beds are being restored.

Bay Field Guide: Bay Grasses (SAV)
Close to 20 species of submerged aquatic vegetation can be found in the Bay and its tributaries. Use this online Field Guide to learn more about these grasses.

Underwater Bay Grass Abundance
The abundance of bay grasses is just one of the many indicators that the Chesapeake Bay Program uses to measure Bay health. Learn more about data trends and goals.

The bathymetric cartography and data displays were designed and built by Stamen, in San Francisco.