As hard as it may be to believe, there's not that much material doing downhole. It's usually as much-ish as a middling stock tank - a few million gallons - tennish or so acre-feet.
Determining cause and effect will be a mighty task.
http://www.forbes.com/sites/davidblackmon/2013/07/01/water-f... goes to the water use, with awater always being the big item. David Blackmon is a bit of an oil industry flack, but his logic and numbers marry up to other sources well.
Given California's politics, the geology ( fault lines ) and the way prices are working out, it's probably better left alone for now. The rate of innovation in fracking is staggering. The technology will be there sooner or later. I have a friend who's roughly from the general Kern County area and its a brittle place environmentally.
This being said, the LA Times is not exactly an oil/gas friendly publication - the quotes were all from professional anti-frackers. Sadly, since the Enron fiasco, we have to watch for that sort of thing. Claiofornia also has had "oil people" and "water people" and "oil and water don't mix."