FEMA camps and "government come for our guns..." -- good grief.
There are enough legitimate things to worry about in our economic climate without paranoid delusions and NRA/Weapons manufacturing propaganda being added to the list of things to worry about. Serious problems require serious solutions, adding FOX "News" lunacy does not help matters.
Wrightwood is within perhaps 90 driving minutes of some 22.4 million people, a great many who actually believe that if there is another economic upheaval in excess of what we had through 2001 and 2009, they will head to the mountains and "live off the land" with their 40 million handguns and rifles.
Beyond basic Earthquake preparedness that every Californian should have, the storage of food and water for mitigation against economic and civil unrest is pointless in the face of a heavily armed populace that can be expected to flood in and take everything you have, killing whoever has it along the way.
Wrightwood is not unique. Every mountain and desert community has the same problem. In the face of a civil or national emergency, all such communities will be overrun with heavily armed people, the majority of them boasting IQs right up there in the mid 80s, every one of which are motivated to take what people have.
Crystal Lake has the same problem, there is potable drinking water at Crystal Lake in the San Gabriel Watershed, and if civil or national unrest were to take place, any point where drinking water is to be found can be expected to be overrun, the game in the mountains (from bears all the way down to snakes) exterminated and eaten within one week.
My point is that every citizen should be storing gasoline, water, food, batteries and such in a standard Earthquake or Fire kit, enough to get through 30 days or so of civic services being cut off, enough to afford citizens to gather together and plan in the aftermath.
The idea that one can plan and mitigate a civil or national upheaval is delusional not to mention paranoid.
I will add that we already have adverse impact from the current Great Recession, we see more and more people squatting in the Angeles National Forest already, many of them living along the East Fork of the San Gabriel River. The pollution from human waste ending up in the river (and thus our drinking water) is truly horrific to the point where there has been periodic cleaning-out of the homeless squatters and illegal miners about twice a year which has managed to bring our water quality back to human consumption levels.
I'll have to read the other comments.

But since I work in the cargo locomotive transportation infrastructure industry and have done extensive work with potable water catchment and distribution, sewage, electricity, intercoastal waterway transportation, and telecommunications, much of my annual training covers incident damage and aftermath damage, vandalism and terrorism disruptions of infrastructure, disease control, a broad spectrum of training to ensure myself and my colleagues keep things
going in the face of adverse effects, my informed opinion is that there is little you can do to ensure your survival in the face of the levels of upheaval that the OP is worried about.
My opinions only, as always, and only my opinions.