What is the HAB Reports Map?

The HAB Reports Map, managed by the State Water Resources Control Board (CA Water Boards), shows locations of reported Harmful Algal Blooms (HABs) in freshwater, estuarine, or marine environments.

Reports come from:

• Online submissions using the Report Form
• Partners and other organizations
• Water monitoring data submitted to the CA Water Boards

Note: Updates for investigations or verified blooms are displayed, but drinking water advisories are not shown here.

How to Use the Map

The map uses colored dots to represent reported HAB locations. Click a dot to see details like:

• Advisory status
• Date of last verification

Dots fade after 30 days without updates.

Need help?

• Email: CyanoHAB.Reports@waterboards.ca.gov
• Phone: 1-800-222-1222

Recreational Safety and Advisories

The CA Water Boards work with local agencies to investigate reports and issue recreational advisories and corresponding signage when needed.

• Refer to California voluntary guidance for recreational waters
• Look for posted signage at affected locations

What You Can Do

Practice Healthy Water Habits when outdoors. If unsure, avoid contact with waterbodies that may be affected by HABs.

Downloading Data

To download the full data set, including reports from all years, go to the California Open Data Portal. The HAB Reports Tracking Map is populated by data in the Freshwater and Estuarine HAB Program's Reports and Monitoring Data System and maintained by the California Water Boards.

Disclaimer

HAB locations may not reflect real-time conditions as environmental changes occur. Blooms may affect specific areas (like shorelines) or entire waterbodies. Information on this map is updated daily, and should be used for general purposes only.

If you notice a missing HAB location, please report it to the HAB Hotline.

For help identifying HABs, check out our visual guide.

Latest HAB weekly update list