Desalination Closer to Reality in California

Aug. 27, 2008 -- California is closer to hosting the largest desalination plant in the country, but not everybody thinks it's a good idea.

Some environmental groups remain concerned about the impacts of the plant on the coastal environment, despite attempts to mitigate these concerns by Poseidon Resources of Stamford, Conn., the company that wants to build the plant. The plant would turn seawater into drinking water and provide a drought-proof water supply for about 300,000 people.

Whether or not the plant goes forward may have an impact on similar proposals around the country. There are, for example, an estimated 17 other proposed desalination plants just in California. Interest in desalination is likely to grow as pressure increases on the nation's water supply, especially in the West.

Late last week the California State Land Commission granted the last remaining permit that Poseidon needed to go ahead with construction of the 50-million-gallon-per-day facility in Carlsbad, Calif., near San Diego, which they aim to have running by 2011.

But Marco Gonzalez, an attorney representing the Surfrider Foundation, a non-profit environmental group based in Encinitas that focuses on waves and beaches, said Surfrider would continue to work to block the plant's construction by following up with lawsuits.

"We recognize that desalination is a likely part of our future water supply portfolio," he told Discovery News. "But our concern is that its time has not yet arrived."

The environmental concerns with desalination are threefold.

The first concern is that the desalination process produces one gallon of super-salty water -- twice as saline as normal seawater -- for every gallon of drinking water. Discharging this hypersaline water back into the sea would create a zone of extra salty water that could harm marine organisms.

To get around this, Poseidon plans to locate their facility in the same spot as a power plant that uses seawater for cooling. The power plant uses several times as much water as Poseidon needs, so Poseidon can dilute the salty water with the water from the power plant before returning it to sea.

However, there are concerns with the environmental impacts of such power plants, too, and several sources suggest that the lifetime of this plant is limited. Poseidon has agreed to maintain the lagoon where the plant would be located if the power plant leaves, and to continue to dilute the water before releasing it.

The second environmental concern is perhaps the biggest, according to Jeffrey Graham, a marine biologist at Scripps Institution of Oceanography, who consulted with Poseidon on the project. "I think the major issue that still is a bone of contention is the extent to which organisms are killed by the process of withdrawing seawater."

Sucking up large amounts of seawater brings with it tiny fish larvae and plankton that are killed as they pass through the desalination process. The need to dilute the saltwater means larger quantities of water must be pulled through the system, increasing the larvae and plankton losses.

"It was dealt with by Poseidon agreeing to pay for the reestablishment of 55 acres of wetland, which is a big commitment," Graham said.

However Surfrider finds this tradeoff unacceptable. He argues the company should draw water from beneath the sand, rather than from the open ocean since that would prevent the entrainment of marine life. Such intakes are more expensive.