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Ocean Plan Requirements for Seawater Desalination Facilities

Seawater Desalination Overview

Why are there requirements for seawater desalination facilities in the Ocean Plan?

Although seawater desalination can be a water supply option for some coastal communities, the construction and operation of these facilities can result in marine life mortality and harm to aquatic life beneficial uses. During the process of ocean desalination, organisms may be drawn in with the source water and enter the facility’s water processing system. Salt and minerals are removed from salt water to produce fresh water and organisms do not survive the desalination process. The salt, minerals, and other compounds produced as a byproduct of desalination are discharged into the ocean as hypersaline brine. Brine is denser than the receiving ocean water and, depending on discharge methods, may settle on the seafloor and have adverse effect on marine organisms. The Ocean Plan includes requirements to ensure the construction and operation of seawater desalination facilities minimize intake and mortality of all forms of marine life.

2015 Ocean Plan Desalination Amendment

On May 6, 2015, the State Water Board adopted an amendment to the Water Quality Control Plan for the Ocean Waters of California (Ocean Plan) to address effects associated with the construction and operation of seawater desalination facilities (Desalination Amendment). The Amendment supports the use of ocean water as a reliable supplement to traditional water supplies while protecting marine life and water quality. The Desalination Amendment, for the first time, provides a uniform, consistent process for permitting of seawater desalination facilities statewide. In doing so, it provides direction for regional water boards when permitting new or expanded facilities and provides specific implementation and monitoring and reporting requirements. The Office of Administrative Law approved the Desalination Amendment on January 28, 2016. The United States Environmental Protection Agency approved the portions of the Desalination Amendment that implement the federal Clean Water Act on April 7, 2016. Therefore, the Desalination Amendment is now fully in effect.

The Desalination Amendment requires new or expanded seawater desalination plants to use the best available, site, design, technology, and mitigation measures feasible to minimize intake and mortality of all forms of marine life. Based on the best available science, the amendment identifies preferred technologies; however, alternative intake and disposal methods can be used if demonstrated to be as protective of marine life as the preferred technologies. Additionally, mitigation measures are required in order to address harmful impacts on marine life that occur after a desalination facility uses the best available site, design, and technology feasible. Feasibility considerations regarding site, design, technology, and mitigation measures take into account economic, environmental, social, and technological factors and whether something is capable of being accomplished in a successful manner within a reasonable period of time.

Seawater Desalination Facilities

Existing Desalination Facilities

Currently, there are 12 existing desalination facilities throughout California. The existing desalination facilities were issued an NPDES permit, building permits and other governmental approvals necessary, and commenced construction of the facility beyond site grading prior to January 28, 2016.

  1. Moss Landing Power Plant
  2. Marina Coast Water District Desalination Plant
  3. Sand City Desalination Plant
  4. Monterey Bay Aquarium
  5. Morro Bay Desalination Plant
  6. Morro Bay Power Plant
  7. Diablo Canyon Nuclear Power Plant
  8. Gaviota Oil Heating Facility
  9. Charles E. Meyer Desalination Facility
  10. Pebbly Beach Desalination Plant
  11. San Nicolas Island Desalination Plant
  12. Carlsbad Desalination Plant
Existing Seawater Desalination Facilities

Proposed Seawater Desalination Projects

The following list includes proposed seawater desalination projects that are ongoing or currently being considered by regional water board staff in consultation with State Water Board staff.

Links to project-specific regional water board webpages are provided where available.

Proposed Seawater Desalination Projects

  If you are proposing a seawater desalination project, please contact your regional water board or state water board as soon as possible.

Regional Water Board Contacts

Region 1 – North Coast
Mona Dougherty
Region 2 – San Francisco Bay
Thomas Mumley
Region 3 – Central Coast
Peter von Langen

Region 4 – Los Angeles
Jeong-Hee Lim
Region 8 – Santa Ana
Terri Reeder
Region 9 – San Diego
Fisayo Osibodu

Seawater Desalination Interagency Memorandum of Agreement

The Seawater Desalination MOA memorializes the relationship between agencies to coordinate timely and effective review of environmental documents and permits or lease applications for proposed seawater desalination facilities, and demonstrates the Water Boards’ ongoing commitment to interagency coordination. The signatories of the MOA include:

  • State Water Resources Control Board
  • California Coastal Commission
  • California State Lands Commission
  • California Department of Fish and Wildlife
  • North Coast Regional Water Quality Control Board
  • San Francisco Bay Regional Water Quality Control Board
  • Central Coast Regional Water Quality Control Board
  • Los Angeles Regional Water Quality Control Board
  • Santa Ana Regional Water Quality Control Board
  • San Diego Regional Water Quality Control Board
  • Monterey Bay National Marine Sanctuary
  • National Marine Fisheries Service’s West Coast Region

Questions or Comments?

Please Contact:

Clifton Herrmann
Recycled Water and Desalination Unit

Laura McLellan
Recycled Water and Desalination Unit