I've lived through the times he talks about and Hanson has it right - almost twice the people but very little more infrastructure. What was adequate forty years ago, is adequate no longer.
BTW, a cold-eyed realist would dam every major canyon coming down out of the Sierra, catch the run-off for the dry years, and generate cheap, clean power with the falling water. Cold-eyed realists aren't popular in today's California, hence the problems Hanson catalogues.