In her latest blog post on The California Spigot, Patricia McBroom reports on new USGS findings that the threat of Delta levee breaches in an earthquake is greater than anyone thought.
The report is based on the response of Delta soils to ten small earthquakes (up to 4.2 magnitude) that have occurred in the East Bay since 2007. The USGS had monitors at eight places in the Delta, including four on Delta levees.
Exporters who want to continue diverting water from the Delta will be using the new USGS report on earthquake threat to bolster their argument for isolated conveyance. That’s exactly the wrong message to take away from this report.
Assuming it is true that earthquake threat to the Delta is high (and engineers in the Delta aren’t convinced), public resources should go first to strengthening the Delta levees protecting people and infrastructure, and to developing regional emergency response. We’ve been arguing for this anyway, and every political tactic that delays levee work or fragments emergency services is indefensible.
If some kind of triage is necessary for deciding where to put levee maintenance resources, then decisions should be made by the Delta counties and communities, without pressure from outside interests that have always been prepared to abandon the Delta in order to ensure continued or increased exports.
Finally, if the risk to water supply reliability is that great, then the whole state should be weaning itself off dependence on water from the Delta. It is the height of irresponsibility to perpetuate reliance on water exports instead of putting all available resources into conservation and regional self-sufficiency.
And by the way, according to McBroom, even if an earthquake did result in some levee failures, that wouldn’t mean the end of the Delta. As soon as it rains, salt water that had entered the Delta through breaches would begin to be flushed out.
That’s another good reason for ensuring that adequate water can get through the Delta, rather than being conveyed somewhere else.