Desalination: Panacea for Our Water Crisis or Dangerous Boondoggle?

California is in the process of building a series of massive ocean desalination plants on a scale not seen before in the United States. While most are at various stages, slowly slogging through bureaucratic red tape, conservationists are pushing back against powerful interests betting California’s looming water crisis occurs sooner rather than later.

Opponents argue the technology is too expensive and damaging to the environment while the state could do a lot more to conserve water at the tap and in the fields where most of California’s expensive imported water ends up. Skeptics also see in desalination a potential boondoggle where the public bears the risk and Wall Street investors reap the benefits.

“We should be doing a lot more in terms of water saving before we go into desalination,” said California Coastal Commission chairwoman Sara Wan.

“Most likely, given the population we have, we’re going to eventually need to do desalination for water,” Wan said. “There are ways to do it that are less damaging and ways that cause significant impact.”

There are now about 20 full-scale proposals for desalination plants – with several smaller facilities already up and running – from San Francisco to San Diego that would turn the salty waters of the Pacific into drinkable tap water. Some plan to draw brackish water through ground wells, while most want to draw millions of gallons of seawater each day through the same in-take pipes that power plants must phase out in 15 years.

Like the power plants, desalination plants have the potential to entrap sea lions, millions of fish and other marine life. The industry says it is reducing harm with newer technologies such as wedge-wire screens, but much depends on location. Wan voted against a large-scale plant in Carlsbad because it would destroy sea life in a nearby estuary, but she supported a plant in Monterey that plans to draw water through near-shore wells. Neither facility is built yet, though both could break ground this year, marking the first large-scale desalination plants in the state.

There are problems too with desalination’s byproduct, the heavy concentrates of salt and the remains of other chemicals that could be dumped into the ocean.

Desalination also has a massive carbon footprint. For the most common type of ocean desalination method called reverse osmosis, which pushes water through membranes, some 40 percent of the operating cost is electricity to power the plant.

The $700 million proposed plant in Carlsbad by investor-owned Poseidon Resources expects to satisfy around 8 percent of San Diego County’s water supply while at the same time consuming as much electricity as 45,000 homes. Greenhouse gas emissions would total about 200 million pounds a year, according to the project’s environmental impact assessment.

Advocates say the technology is becoming more efficient by re-capturing energy and using renewable resources as much as possible. But it is a lot to overcome.

Drawing water

Most of what the state knows about ocean water in-take pipes comes from the impact of 19 coastal power plants. In 2009, the State Water Resources Control Board ordered those plants to phase-out the use of surface water in-take pipes for cooling their red-hot equipment, the sole reason they are located on the coast in the first place. The state’s governing body on water determined those in-take pipes kill 9 million fish, 57 sea lions and other marine life each year.

But those orders do not apply to desalination plants, which expect to use many of those same pipes, often at equal capacity, long after power plants are barred from doing so.