I have lived in California's Central Valley for decades and understand some of the demographic and climatic challenges of this state. Water is not the only resource that gets sucked up by the huge cities (voting blocks) on the coast. In addition to the dryness, it gets infernally hot in the northern Sacramento Valley and in the southern San Joaquin Valley during the summer.
California's barest nod to valley bicycle touring, in the form of the water-stealing-canal maintenance roads, is not pretty and is wholly inadequate: the paths are completely exposed (not a tree in sight), have no facilities anywhere (can't swim in them, can't drink from them), every bisecting country road has a set of "bike-unfriendly" gates to negotiate (even without panniers or trailer), and there are no "destinations" at start or finish (a path to and from nowhere.)
These are tremendously large valleys, with relatively few people living in them. California's State Route system roads usually have some decent shoulders on them, but those quite often get dicey or peter out altogether.
All that said - and lack of bike route notwithstanding - I am planning to ride State Route 33 from Tracy to Ventura this summer (July 2013). Wish me luck.