Why Californians Will Soon Be Drinking Water from Mexico's Ocean

Yesterday, the Department of the Interior released a pretty scary report about the impacts of climate change on water in the Southwest. The report (PDF), which "represents the first consistent and coordinated assessment of risks to future water supplies across eight major Reclamation river basins," paints a frightening picture of an already arid region that undergoing a long, painful desertification.

In the past, we've looked at the desalination of seawater as an option for providing drinking water in regions that lack freshwater, like Australia and the American Southwest. While I wish there were ways to keep demand for freshwater within the means supplied by natural systems, I'm of the opinion that desal isn't just going to be an option, but a necessity for some areas by mid-century.

So it was fascinating to read Rob Davis's voiceofsandiego.org feature on how lax regulation in Mexico could make it easier and cheaper to build desalination plants off the Baja coast, and how those could soon be supplying water to Southern Californians.

Desalination offers the promise of being a drought-proof local supply in an arid region that imports most of its water from hundreds of miles away. But it is highly regulated in California because of its environmental impacts, such as massive pumps that suck in and kill fish larvae and other marine life...

"They don't ask as many questions" in Mexico, said Peter Douglas, executive director of the California Coastal Commission, the state agency that regulates coastal development. "They don't protect the environment like we do in California."

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Right now, authorities are talking about building one desal plant in Mexico. There's another planned in the San Diego area, that's a similar size. But those aren't going to get us very far. On his blog, John Fleck digs into these numbers a bit:

But what struck me about this project, as Rob describes it, is how small it really is. 50 million gallons per day is about 56,000 acre feet per year. The average Lake Mead shortfall during the ’00s was 1.2 million acre feet per year. That’s the supply-demand imbalance we’re talking about. That would mean 20-plus desal plants just to close the current gap.

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Conservation measures are, of course, essential, but I simply don't see any way that Southern California will be able to sate its thirst for drinking water without these massive, energy-sucking plants. We'd better figure out how to build and operate them without totally ruining the coastal ecosystems, and without using so much carbon-spewing energy that will just worsen the freshwater shortages in region.