California, watersheds, and using water
At Angry Bear and other sites a common proposal in comments is to bring increasing amounts of water from other watersheds into the area or desalination. It often stays at an abstract and macro level, or as a pitch for conservation at the urban/suburban level for low water volume devices to use at home. Surely there are things to consider (recycled water, boring agricultural issues) before
Replumbing California offers a starting point on the drought problems in California, part 2 here.
A summary of Cadillac Desert, an old but classic documentary can be seen on youtube here.