Former water district CEO discusses desalination

Steve Pomeroy/Special to the Town Crier
Stan Williams, former Santa Clara Valley Water District CEO, addresses the Rotary Club of Los Altos Jan. 28.


The need to find new water sources is critical, according to Stan Williams, vice president of project development for Poseidon Water in Carlsbad.

“Global water consumption is doubling every 20 years, and all accessible fresh-water resources are already allocated,” Williams told the Rotary Club of Los Altos Jan. 28.

Williams, who moved to the private sector after 13 years as CEO of the Santa Clara Valley Water District, mentioned desalination of seawater as a solution to the state’s pressing water needs. At the rate Silicon Valley’s population is growing, he noted, a multipronged approach is necessary: seawater desalination, conservation, water recycling and improvement of infrastructure such as reservoirs.

Williams said the benefits of seawater desalination include its reliability, high water quality, local control and the fact that it’s drought-proof.

Seawater reverse osmosis is scalable, according to Williams. Poseidon now supplies 8 percent of all water needs in San Diego County, he noted. Under contract for 30 years with the San Diego County Water Authority at a cost of $922 million, Williams said Poseidon has built within budget and on time the largest seawater desalination plant in the Americas.

The company’s desalination plant is also the first large-scale seawater reverse osmosis plant in California, he added. The Carlsbad plant’s 16,000 membrane cartridges produce such high-quality water that it goes directly into the San Diego County water supply system. Recycled water, on the other hand – even if treated with advanced technology – would be required to be indirectly stored with groundwater before being certified as fit for human consumption. One unit of seawater produces 1/2 unit of potable water and 1/2 unit of doubly salty water that is diluted with water and diffused before being returned to the ocean.

Desalination is safe for the environment, Williams reported, as the impact on marine life of the seawater intake and brine discharge can be fully mitigated and is regulated by the State Water Resources Control Board.

During his time at the Santa Clara Valley Water District, the district won numerous accolades for its environmental stewardship. Williams now works with the California Coastal Commission to convene the Independent Scientific and Technical Review Panel for the Huntington Beach Desalination Project to evaluate Poseidon’s environmental stewardship.

The energy required for seawater reverse osmosis, he said, is similar to or lower than that used by many common items, including water heaters, air conditioners and electric vehicles. He suggested that the excess energy produced mid-day in California by renewable energy sources like solar and wind could also be harnessed for desalination.

Texas and Florida are now using desalination processes as well. Because reverse seawater osmosis requires a ready supply of the ocean’s water, it can only take place on the coast, Williams said, and Californians are fortunate to possess such a long coastline.

Marlene Cowan is a member of the Rotary Club of Los Altos. For more information, visit

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