The U.S. Government is closed. This site will not be updated; however NOAA websites and social media channels necessary to protect lives and property will be maintained. To learn more, visit www.commerce.gov. For the latest forecast and critical weather information, visit www.weather.gov. 

The U.S. government is closed. This site will not be updated; however, NOAA websites and social media channels necessary to protect lives and property will be maintained. To learn more, visit commerce.gov. 

For the latest forecasts and critical weather information, visit weather.gov.

How can you spot a bloom? Look for discolored or reddish-brown water, dead fish, or large patches of algae on the surface.

Aerial view of a coastal area with water showing dark brown and greenish hues, indicating potential algae. The shoreline features docks, trees, and some buildings.Over the past two decades, blooms from species like Alexandrium and Margalefidinium have become more common in the Bay, threatening local fisheries, ecosystems, and water quality.

How can you spot a bloom? ➡️ Look for discolored or reddish-brown water, dead fish, or large patches of algae on the surface. Some blooms are toxic, even if the water looks clear.

NCCOS is working with partners to monitor and forecast these emerging threats so communities can stay informed and safe.

Learn more about HABs in the Chesapeake Bay: https://cdn.coastalscience.noaa.gov/projects-attachments/528/HABs-in-ChesapeakeBay-August-2025.pdf  

Photo credits: W. Vogelbein/VIMS and M. Mulholland/ODU