Harmful Algal Blooms Water Quality Objectives for California Inland Surface Waters, Enclosed Bays, Estuaries, and Coastal Lagoons

The State Water Resources Control Board (State Water Board) is developing statewide water quality objectives for harmful algal blooms (HABs) and a program of implementation to reduce the risk and occurrence of HABs in California’s inland surface waters, enclosed bays, estuaries, and coastal lagoons. The objectives and program of implementation will be proposed as state policy for water quality control and as a statewide water quality control plan.

The project was previously called the Biostimulation, Cyanotoxins, and Biological Conditions Provisions and was focused on developing statewide numeric objectives for nutrients and other indicators of eutrophication or biostimulation.

Project Goals

The project aims to establish water quality objectives and implementation requirements crucial for consistent protection of California's waters, specifically to:

  • Protect the municipal and domestic water supply (MUN) and water contact recreation (REC-1) beneficial uses from HABs and reduce the risk and occurrence of HABs in all inland surface waters, enclosed bays, estuaries, and coastal lagoons.
  • Establish consistent, statewide HABs water quality objectives and a coordinated, consistent program of implementation to attain them.

Project Updates

State Water Board staff is developing numeric water quality objectives to protect the MUN and REC-1 beneficial uses from four cyanotoxins, which are microcystins, cylindrospermopsin, anatoxin-a, and saxitoxins. Staff is also developing a narrative water quality objective for HABs and a program of implementation to achieve the numeric and narrative objectives and reduce the number of incidents of HABs in California.

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  (Page last updated 1/16/26)

 
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