Here's an unfortunate hypothetical: An earthquake strikes along the San Andreas fault, damaging three aqueducts that cross it some 32 times. Those aqueducts supply Los Angeles with all but 12% of its water—meaning a serious quake could ultimately leave 22 million people without water. (There would be about six month's worth of water stored on the LA side of the fault, but fixing busted aqueducts could take more than twice that long.) Officials have been aware of the potential for a single quake to hit all three aqueducts since 2008, but as the Los Angeles Times reports, they're now moving to do something about it for the first time. But any solution is pretty far off, in terms of time and money—in terms of the latter, the LAT uses the word "billions."
None of the aqueducts has yet had to deal with the scenario; the last huge quake (magnitude 7.9) along the fault was in 1857. The Los Angeles aqueduct travels across the fault under a mountain, by way of the five-mile-long concrete Elizabeth Tunnel. Building a brand new tunnel is the priciest option; sending water over the mountains via an electric pumping mechanism is another idea. In the case of the Colorado River Aqueduct, a quake could raise a section of the pipe by 13 feet, and there aren't any pumps in place to ferry the water to LA. The mayor last week requested that proposals on the issue be submitted by July. Meanwhile, the San Diego Union-Tribune reports that there may be another fault to fear: It points to new research that shows the San Jacinto fault could generate an earthquake as powerful as what the San Andreas fault is capable of. (Read more earthquake stories.)