California Harmful Algal Blooms (HABs) Portal

The CA HABs Portal is the central resource for HABs in the state of California. HABs can pose a health risk to people and animals, harm aquatic ecosystems, and limit the use of drinking and recreational waterbodies due to the toxins, odors, and scums or mats they can produce.

The Portal is an informational resource for the public and also functions as a tool to support coordination with statewide partners to address HABs. The content is developed by the California Cyanobacteria and HAB (CCHAB) Network and participating state agencies.

The content in this Portal focuses on freshwater and estuarine HABs.

For information on marine (coastal) HABs, including red tides, please refer to the California Harmful Algal Bloom Monitoring and Alert Program (CalHABMAP) and CDPH's Marine Biotoxin Monitoring Program webpages.

  • San Francisco Bay marine HAB event –
    • A marine HAB (also known as a red tide due to discolored red/brown water) is currently impacting the San Francisco Bay and Estuary in multiple areas. Updates on areas impacted by this red tide is available at: Toxic Phytoplankton Observations Map ( For questions please contact
    • The CA Water Boards recommends that people and pets stay out of discolored water until the bloom dissipates. Contact with the bloom can cause an allergic reaction or irritation. More information on and ways to report potential human and animal impacts are available at Marine HAB-related illness tracking.

Healthy Water Habits Video
Understanding the Dangers of Blue-green Algae (Cyanobacteria)
Credit: Department of Water Resources

Healthy Water Habits Video

HAB Incident Reports Map
HAB Incident Reports Map provides data on voluntarily reported blooms in California.
The data may include reports under investigation and/or confirmed incidents of HABs.

HAB Incident Report Map

HAB Data Viewer
HAB Data Viewer presents individual maps that displays data from satellite imagery
and special assessments conducted at local waterbodies.

HAB Data Viewer map