Why are Bay Area cities looking east, to the Modesto and Oakdale irrigation districts and other valley water agencies, for more water rather than tapping into the Pacific Ocean?
The answer is the high costs.
While there have been some improvements in membrane technology, desalination remains a very expensive alternative -- generally far more expensive than conservation, recycling and purchasing water. A study being released today by the Pacific Institute examines the financing complexities associated with desalination plants.
The price of making salt water potable for drinking runs anywhere from $1,900 to $3,000 per acre-foot, according to the study by the institute's Heather Cooley and Newsha Ajami. In contrast, San Francisco had offered the Modesto Irrigation District $700 per acre-foot for a long-term deal that the MID nixed. San Francisco is now negotiating with the Oakdale Irrigation District; the amount and price are presumably items on the table for discussion.
In 2006, the institute published a report, "Desalination, with a Grain of Salt," that looked at 21 proposed projects in California. Only one of them is operational today; another has the needed permits but not the financing. This week's report is part of a series of follow-up studies on desalination.
While the cost of desalination has dropped some, it isn't expected to get significantly cheaper, Cooley said in a phone interview. A big reason is that more than a third of the operational cost is for energy, which is as or more expensive than it used to be.
Many of the costs of the desalination are typical of the capital expenses for any big project: environmental reviews, permits, land, cost of steel and other building materials, and so on.
But there are other costs, too, including disposing of the waste water -- brine, basically -- that is created in the desalination process.
The study looks at something called "demand risk." During a drought, for instance, there may be a demand for expensive water because there are no other alternatives. But once the drought is over, the demand for the costly water subsides.
As a result, a desalination plant that had operated at full capacity might be cut back to half operations or idled. That is what happened to one plant built in Santa Barbara.
San Francisco, which is the willing buyer for water from our region, is part of a five-member partnership looking at a desalination project near Pittsburg. It is relatively small and is on the delta, where the brackish water has a lower salt content than seawater.
Still, it is likely to run into some of the same challenges facing other desalination projects.
The Pittsburg plant is one of 17 proposed in California. Cooley said it is unlikely all will be constructed, and the decisions will depend on when, where, how -- and how much they will cost.