Tag Archives: seawater desalination

Status of Desalination Plants in California

Peter Lobner

Updated 20 December 2015

On 9 June 2015, Forbes reported that the Diablo Canyon NPP, located on the coast near San Luis Obisbo, CA, meets 100% of it’s own fresh water needs with it’s own reverse osmosis (RO) + ultrafiltration desalination plant.

Diablo-Canyon-Nuclear-Power-Plant  Source: PGE

Diablo Canyon salination_1 Source: PGE

This is the largest desalinization plant currently operating on the West coast. The current fresh water production rate is 675,000 gallons/day; about 40% of full capacity: 1,500,000 gallons/day (1,681 acre-feet/year). The Forbes article suggests that the Diablo Canyon NPP would quickly be able to help the nearby communities that currently are experiencing a severe water shortage as a result of the four-year California drought. With some additional modular RO units and a pipeline to connect to the public water system, up to 825,000 gallons/day could be delivered for public consumption.

Other operating desalination plants in regular use in California are:

Sand City Coastal (seawater) Desalination Plant in Monterey County: 300 acre-feet/year (268,000 gallons/day).

  • Southern California Edison seawater desalination plant on Catalina Island: 224 acre-feet/year (200,000 gallons/day).
  • Cambria Community Services District brackish water desalination plant, which began operating in early 2015, providing 250 acre-feet/year (223,000 gallons/day), about 35% of the town’s fresh water needs.

Other desalination projects in California include:

  • The Posiedon Water seawater desalination plant in Carlsbad, CA, which is expected to have a capacity of 56,050 acre-feet/year (50,000,000 gallons/day) after it is completed in November 2015. This plant will meet about 7% of San Diego county’s fresh water needs.


Source: San Diego Water Authority

  • The Posiedon Water seawater desalination project in Huntington Beach, which is in the final phase of permitting and is expected to be completed in 2018, also with a capacity of 50,000,000 gallons/day.
  • The Doheny Ocean Desalination Project in south Orange County, which is planned to deliver 16,816 acre-feet/year (15,000,000 gallons/day), with a target completion date of 2020.
  • The city-owned Charles E. Meyer desalination plant in Santa Barbara, which was mothballed in 1992 after a short test period. Plans are being prepared to modernize and re-start this plant, which has a licensed capacity is 7,500 acre-feet/year ( 6,691,0000 gallons/day) and can meet about 30% of the city’s fresh water needs.
  • Four new desalination plants on the Monterey peninsula are in the planning stage:
    • Marina Coast, Armstrong Ranch brackish water desalination plant: 2,700 acre-feet/year (2,409,000 gallons/day)
    • California American Water, Monterey Peninsula Water Supply seawater desalination plant: 9,750 acre-feet/year (8,698,000 gallons/day)
    • Deepwater Desalination, Moss Landing seawater desalination plant: 10,000 acre-feet/year (8,922,000 gallons/day)
    • People’s Project: Moss Landing seawater desalination plant: 13,400 acre-feet/year (11,950,0000 gallons/day)

You can find more details on California desalination plants at the following links:

The Forbes article:


The Diablo Canyon NPP seawater desalination plant (video):


Posiedon Water’s Carlsbad seawater desalination plant:


Posiedon Water’s Huntington Beach seawater desalination plant:


Santa Barbara’s Charles E. Meyer seawater desalination plant:


The several Monterey peninsula desalination projects:


The Cambria brackish water desalination plant:


Catalina seawater desalination plant:


Sand City Coastal (seawater) desalination plant:


The Doheny Ocean (seawater) Desalination Project:


20 December 2015 update

The sea water desalination plant in Carlsbad, CA was officially dedicated on 14 December 2015 in a public ceremony attended by more than 600 elected officials, community leaders and project partners.  Formerly known as the Poseidon desalination plant, the plant was officially named in honor of former Carlsbad Mayor, Claude ‘Bud’ Lewis. A 30-year Water Purchase Agreement is in place between the San Diego County Water Authority and Poseidon Water for the entire output of the plant, which started delivering water earlier in December.  This is the largest sea water desalination plant in the western hemisphere.

You can get more information at the home page for this plant at the following link: