Ok. Here's where I leave off all the technicalities of the huge infrastructure that's been created here to capture snowmelt and rain (before it drains to the ocean) and disperse it to the people and the land. But here's a picture of our biggest reservoir (it's actually the biggest "off-stream reservoir" in the US). And check out the water level. Anything that's brown, including those trees, should be covered with water.
Hmmmm, I've already used too many words in this post, sooooo, longer story shorter: not only does California have lots of people and lots of agriculture (and too little rain), it also has lots of lawyers and lots of special interest groups. Currently, a judge has issued an order not to pump any water into this reservoir due to some group's concern that the Delta Smelt (a fish) is heading toward "endangerment of extinction" status (nevermind that there's no proof that Smelt population is tied to pumps or water level ... stick a bandaid on it NOW and stop pumping!!!).
And further down the road ... here is some of the agriculture that's apparently not as important as the Smelt.