California Satellite HAB Map

This Water Boards sponsored mapping tool displays satellite imagery that is used to estimate harmful algal blooms and associated parameters in many of the largest waterbodies in the state. To learn more about locations of reported HABs and their applicable health advisories, please refer to the HAB Reports Web Map.

New! While this tool has focused on estimating cyanobacteria, in June 2023 a second data type was added from Sentinel-3 satellites and are now available for estimating chlorophyll-a (Chl-a) concentrations in surface waters.

This mapping tool displays estimated levels of cyanobacteria and Chl-a in large waterbodies, calculated from satellite imagery in order to better understand potential risks to public health and assess primary production in large waterbodies across California. Approximately 250 waterbodies are displayed due to the resolution of the Sentinel-3 satellites. Data is displayed in map form to show the spatial extent of blooms and is also viewable in long and short timelines to show how concentrations vary over time.

Upon opening the tool, the statewide view allows users to view the status of either cyanobacteria or Chl-a concentrations across a region by selecting the data type under the “Imagery” button in the upper left corner. When users are zoomed into the waterbody level screen, the options in the graphs to the right can be used to toggle between data types or view them paired under “comparison graphs” tab. Additional help and instructions are found in the upper right corner of the screen.

Important information about the satellite map estimating cyanobacteria (CIcyano) and chl-a: The cyanobacteria and chl-a data is used as a screening level analysis tool. For example, if the satellite shows a potential bloom, this can prompt field verification and sampling to confirm the status of a potential cyanobacteria or marine harmful algal bloom. No regulatory decisions, or health advisory postings, should occur based solely on information from the map. More information about freshwater harmful algal blooms can be found at:

  • The map shows estimates of cyanobacterial abundance and chl-a near the surface of a waterbody.
  • The map does not show any information about toxin concentrations and public health advisories.
  • The map shows data collected over a 1 and 10-day windows and does not display real-time conditions at a waterbody.
  • All data on the map are currently considered provisional.

The Satellite HAB map is managed by San Francsico Estuary Institute in contract with the Water Boards agency, using data from the National Oceanic and Atmospheric Administration. Contact with any questions regarding the tool.

View the satellite data.

Recommended citation: California State Water Resources Control Board, San Francisco Estuary Institute, National Oceanic and Atmospheric Administration. California Harmful Algal Bloom Satellite Tool (2002-current);, released January 2016.