The Bureau of Reclamation is pretty much at fault for the lack of water available for human consumption because of mismanagement and prices below the cost which encouraged over development of farming.
The current drought can likely be traced to changes in the Pacific Ocean dating to 1976 [3]. As in, we have more than time enough to see something was changing.
What can be done? Rationing won't solve it all. The states need to have more control over the water that the Bureau of Reclamation currently controls. They are in a far better position to understand their needs and cooperate amongst each other instead of using the weight of Washington politics to force a way.
First and foremost priorities have to be set and reasonable prices for the cost of water need to be assigned. Yes this will likely mean a reduction in farming but it is artificially propped up now by unrealistically low water prices. People also need to understand conservation and large lawns should either be restricted or the water use for such maintenance needs to be surcharged.
The key is better use of resources and not redirecting the problem which is more mismanagement than natural causes.
note, I haven't read much on site #2, but they consolidated nicely some NOAA charts which make it easier to view.
[1] http://docs.lib.noaa.gov/rescue/mwr/061/mwr-061-09-0251.pdf [2] http://www.coyoteblog.com/coyote_blog/2015/01/california-dro... [3] http://icecap.us/images/uploads/More_on_The_Great_Pacific_Cl...