Do I exaggerate? Time will tell.

One similarity can't be denied: levees can fail in California, just as they failed in Louisiana. And if they do, a major disaster and economic collapse could befall our culture, just as it befell New Orleans'.

If a big — 6.9 or larger — enormous earthquake hits the Bay Area and the Sacramento-San Joaquin Delta, which geologists are confident will happen in the next twenty years, than it's possible or likely that dikes in the Delta will collapse, and the State Water Project will be unable to deliver much water to much of Southern California. 

That's not my contention. That's the contention of a recent book called "A Dangerous Place," by the late Mark Reisner, of "Cadillac Desert" fame. Here's one of the many alarming quotes he gathers and quotes:

"MWD [Metropolitan Water District] is so worried about the stability of the Delta in a major earthquake that we've done quite a bit of computer modeling to play with the consequences. The worst case would be a mass levee failure during an intense drought like we had in l976 and l977. Based on our models, we might lose our Northern California water supply for as long as three years."                                     –Paul Teigan, senior engineer w/MWD

And although the book was published in 2003, the threat remains. Last year California's Department of Water Resources published a report making the same point, with greater specificity: 

The report, from
the Department of Water Resources, found there is a 40% probability of
an earthquake of magnitude 6.7 or higher causing 27 or more islands to
flood at the same time in the next 25 years. If
20 islands were flooded, the flow of fresh water through the delta
could be interrupted for a year and a half, the report found. Emergency
repairs on 20 islands could cost up to $2.3 billion and take about three
years.

Another interesting point from A Dangerous Place. The Delta soil is peat, which oxides readily, and has none of the durability of clay. Over the years much of it has sunk below the water level. This is the area protected by levees, and it totals twenty or thirty times the size of Manhattan. Writes Reisner:

What you had there now was a vast empty reservoir, a man-made hole in the California landscape. With levee protection lost, the below-sea-level Delta would become, in effect, a vacuum, which nature abhors. Water would pour in there as it would down a manhole. A lot of it would be saltwater sucked in from the bay. If a strong tide was pushing in when the levees failed, things would become that much worse. If it was summer or fall and freshwater outflow from the Delta was meager, it would be worse still. Half of the water supply of greater Los Angeles, San Diego, and the San Joaquin Valley goes through the Delta. Two-thirds of greater San Jose's — which is to say, much of Silicon Valley — water comes from the Delta. Within hours or days, all that water would be unusable and undrinkable until the incursive seawater was pumped out. 

Reisner quotes a senior engineer who argues there is no good fix for the levee system, which is impossible to protect in case of a big earthquake, because making the levees bigger might actually make them more likely to fail in a big earthquake.

Take a look at this picture, and you can imagine why it's not an easy area to protect: 

The only solution?

The only way to keep fresh water flowing reliably south was to bypass the whole region — to divert the water into a canal that circumnavigated the whole precarious artifice of crumbly levees atop unstable ground. In other words, build the Peripheral Canal — the same huge connector that northern Californians had for decades ferociously, and successfully, opposed.

Hmmmm. One has to wonder if this is the real driver behind the $11 billion water bond, that the Governor and his allies want to withdraw from this year's ballot…for fear it will fail.  

Think they're right about that. But what if they're also right to gulp for fear of lack of water in SoCal?