Seawater desalination gains momentum in California

Many Californian coastal communities are planning to make seawater desalination a permanent part of their water portfolio within the next decade. By 2020, more than 20 seawater desalination plants will supply up to ten percent of California’s total water demand.

Oct 1st, 2006

Many Californian coastal communities are planning to make seawater desalination a permanent part of their water portfolio within the next decade. By 2020, more than 20 seawater desalination plants will supply up to ten percent of California’s total water demand.

Nikolay Voutchkov

Over the last several years, harvesting fresh water from the Pacific Ocean has been riding a rising tide of interest in the US state of California as many coastal municipalities and utilities are challenged with population growth pressures, dwindling water supplies, and escalating water production costs. By year 2030, state’s population is projected to increase from 36.5 to 48 million, which in turn would require approximately four million m3/day of new fresh water supplies. In recognition that relying only on traditional water supply sources, conservation and reuse may not be sustainable in the long term, the California Department of Water Resources (DWR) has charted a new course for exploration of seawater and brackish water desalination as an alternative water supply source for the state.

Figure 1. Location of seawater desalination projects in Southern California, USA

In November 2002, California voters passed legislation (Proposition 50), which authorized the DWR to administer a US$ 50 million desalination grant program aimed to assist water utilities statewide in the implementation of brackish water and seawater desalination projects. The first round of this program was carried out in 2005 by awarding US$ 24.75 million to 24 different desalination projects. The second round of the DWR program awarded another US$ 21.5 million of grants to 23 projects in June 2006. The grand funding was allocated to feasibility studies; applied research, development and pilot testing activities; and to the implementation of demonstration and full-scale desalination projects. The funded projects are planned to be completed by 2009 and are expected to yield practical solutions to key environmental, energy and cost challenges facing desalination today.

With the comprehensive Proposition 50 desalination grant program and the incorporation of desalination into the newest California Water Plan, the state has formally recognized and encouraged the use of desalination as a viable water supply alternative. The California desalination initiative is expected to yield more than 20 new projects statewide, which would supply up to ten percent of the total water demand along the coast by year 2020 and would produce approximately two million m3 of new drinking water by 2030. Specific ongoing seawater desalination initiatives throughout the state are discussed below.

Seawater desalination in Southern California

Currently, Southern California imports 50% of its water from two main sources – the Sacramento Bay – San Joaquin River Delta, traditionally known as the “Bay-Delta” and the Colorado River. In order to address the uncertainties associated with the long-term use of imported water from the Bay Delta and Colorado River, a number of Southern California water utilities have charted plans for a long-term diversification of their water supply portfolios with seawater desalination. By year 2020 all Southern California coastal utilities are planning to supply 10 to 20% of their drinking water from the ocean. Currently, there are a number of large seawater desalination projects in various stages of development. The capacity, intake type, target completion date and projected cost of desalinated water for these projects are summarized in Table 1.

At present, the two largest and most advanced seawater desalination projects in Southern California are the 200,000-m3/day plants planned to be located in the City of Carlsbad and Huntington Beach, respectively. Both projects are collocated with large coastal power plants using seawater for once through cooling. The desalination projects are developed as public-private partnerships between Poseidon Resources and local utilities and municipalities. The environmental impact assessments and local land use permits for the two projects have been completed, reviewed and approved in the first half of 2006. Both projects have been found viable and environmentally safe. The permitting process for the two projects is expected to be completed by the end of 2006 and project construction is planned to begin in 2007. The projects are targeted to be in operation by the end of 2009 and to supply six to ten percent of the drinking water in Orange County and San Diego County, which are the two largest counties in Southern California.

All projects listed in Table 1, with exception of the Huntington Beach and Carlsbad desalination facilities, are at the stage of initial feasibility assessment. The City of Long Beach Water Department, the Los Angeles Department or Water and Power, the West Basin Municipal Water District, and the Municipal District of Orange County are planning to embark on pilot or demonstration scale studies by the end of 2006.

Seawater desalination activities in Northern California

The need for supplemental drought-relief water supplies, groundwater basin overdrafts and associated seawater intrusion, and the measurable ecological impacts of some of the current water supply practices are the main driving forces for the renewed interest in seawater desalination in Northern California. Most of the proposed projects are located in the San Francisco Bay Area and in Monterrey County.

Currently, a partnership of San Francisco Bay Area water districts (Contra Costa Water District, Easy Bay Municipal Water District (EBMUD), Santa Clara Valley Water District and the San Francisco Municipal Utility District) are studying the feasibility of several seawater desalination plant locations – one in San Rafael in partnership with the Marin Municipal Water District (MMWD), one in Oakland, and one at the Mirant Power Plant in Pittsburg, Contra Costa County. A fourth location is also considered – a site near Ocean Beach on the Pacific Ocean. If construction of seawater desalination plants is found viable, this initiative may yield one to three seawater desalination plants with a total production capacity of 76,000 m3/day to 303,000 m3/day within the next five years. The San Francisco Bay seawater desalination feasibility study should be completed by the end of 2006.

At present, EBMUD is developing another seawater desalination facility to be located at the C&H Sugar food processing plant in Crockett. This facility would use up to 11,300 m3/day of cooling water from the food processing plant to produce 5,700 m3/day of desalinated water which will be applied for industrial uses. The desalinated water would replace the drinking water currently received by the refinery from EBMUD. The concentrate from the desalination plant will be discharged through the existing wastewater outfall of the C&H Sugar plant.

Marin Municipal Water District is also developing a large seawater desalination project in the San Francisco Bay area. This project is targeted to produce between 38,000 m3/day and 57,000 m3/day of desalinated water and to provide reliable, drought-proof alternative to the construction of a new pipeline for supplemental water supply from the already over-allocated Russian River. Marin Municipal Water District has recently completed a 12-month desalination pilot test and is well under way with the preparation of environmental impact assessment for this project. Draft environmental impact report is expected to be circulated for public review by the end of 2006.

Monterrey County, which is located south of the San Francisco Bay Area, is currently the grounds for the development of several new seawater desalination projects. Two large competing projects are proposed in the City of Moss Landing. The first project is a regional seawater desalination facility planned to be delivered under a public-private partnership between Pajaro-Sunny Mesa Community Services District and Poseidon Resources. The regional desalination plant would be located at a former National Refractories industrial plant site, which is adjacent to the Moss Landing Power Generation Station. This desalination project would use the existing National Refractories open intake and ocean outfall. Alternatively, the project developers are considering to supply warm cooling seawater to the desalination plant from the Moss Landing Power Generation Station, when available, in order to reduce impingement and entrainment of marine organisms, and to minimize the amount of power used for reverse osmosis separation.

Most of the potable and irrigation water used in Monterey County comes from a coastal aquifer, which has been steadily increasing in salinity due to over-pumping. The main purpose of the regional seawater desalination project proposed by the Poseidon/Pajaro- Sunny Mesa team is to replace the use of groundwater from the coastal aquifer with desalinated seawater and thereby to minimize further seawater intrusion.

The California American Company (Cal- Am) is developing a smaller, 45,000 m3/day project at the Moss Lending Power Generation Station site and proposes to use the power station’s cooling water discharge as an intake and discharge of the desalination plant. The main purpose of this project is to offset the environmentally damaging diversion of large volumes of fresh water from Carmel River, which currently is used as a main source of water supply to the Cal-Am’s customers in the southern part of the county. Although this project is developed in a parallel track with the Pajaro-Sunny Mesa/Poseidon desalination project, most likely only one of the two projects will be built. The regional desalination project proposed by Pajaro- Sunny Mesa/Poseidon is designed to accommodate Cal-Am’s water demand.

Besides the several large projects described above, there are a large number of other smaller projects under development in Northern California. Most of these projects are in early phases of feasibility and environmental studies, and are not expected to yield full-scale desalination plants before 2010.


Many Californian coastal communities are planning to make seawater desalination a permanent part of their water portfolio within the next five to ten years. More than 20 seawater desalination plants supplying up to ten percent of California’s total water demand are projected to be built by 2020. Although existing fresh water sources, conservation, and reuse would continue to play a central role in the state’s long-term water supply strategy, seawater desalination has a unique appeal to many coastal communities because it allows access a reliable and drought-proof source of drinking water that can be developed and controlled locally.

Author’s Note

Nikolay Voutchkov is the senior vice president of technical services for Poseidon Resources Corporation, based in Stamford, Connecticut, USA. For more information, contact the author by email:

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