Monday, November 5, 2007

No salt, please. Desalinating the Bay for Marin

My home county does not, like most of California, depend on snow melt from the Sierras for its water supply. Nor does it, like most of the remaining regions, rely on water from a river. Marin - specifically southern and middle Marin - gets its water from seven reservoirs in the hills covering the central region of the county. These catch run-off from Mt. Tamalpais and its greater water shed. But the rising population and the needs of more large houses with expensive landscaping have combined with the acknowledgement of a greater chance of drought to create a need for another source of water.

I've mentioned the option of a desalination plant, sucking water from the San Francisco Bay and filtering it by reverse osmosis. Now, the talk has escalated to a public environmental impact hearing at the Marin Municipal Water District HQ, where the $115 million first stage plant will be described. No, there are no funds available for the plant; new taxes and/or higher water bills would raise the money. And no, there is no firm plan for mitigating damage from the return of concentrated brine to the bay after the pure water is extracted. Nor is there a plan for generating the electricity required to run the plant, especially in the case of drought, when the plant would need to produce up to twice as much drinking water as during more normal times.

So, lots of unanswered questions. But at least it's a sign that my county is thinking adaptively. Hopefully, this proposal will be accompanied by more public education about conserving the water we have now, when we're only in a mildly drier than normal period.

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