As a longtime resident of Southern California, I was blissfully unaware of the apocalyptic dangers posed to the entire state should something go amiss with the levees in Sacramento, until my best friend moved northwards and he told me about it.

This interactive map from Bloomberg’s Paul Tullis and Evan Applegate really makes the point hit home. It’s frightening:

The scenario is known as “California’s Katrina.” An earthquake or superstorm causes Gold Rush-era earthen levees to collapse. Saltwater from San Francisco Bay floods the Sacramento-San Joaquin River Delta, displacing half a million lowland Californians, poisoning the water supply for as many as 28 million more who live in Los Angeles, San Diego, and Silicon Valley, and ruining farmland that produces 11 percent of the nation’s agricultural value. The eighth-largest economy in the world could be sunk for months, even years.

There are two competing proposals to avert all this. The first is to bypass the delta with tunnels carrying fresh water to Southern California. The second is to upgrade the existing levees. A bill that would have required an official cost-benefit analysis of these approaches got shot down in the state legislature. Civil engineers at University of California at Davis don’t think the levees can be earthquake-proofed. Delta landowners, fearful the levees will no longer be maintained if the tunnels were built, have refused surveyors access to their land.

In this fight, if someone doesn’t win, everyone will lose.

It’s worth noting how many naysayers there are in the comments, but if California’s farmlands and fresh water supply is even the slightest bit in danger, that’s unacceptable. The accusations that this is “alarmist” are ridiculous.

How the hell could you be too alarmist about something like this smack in the heart of earthquake country?