This assumes that population growth continues its pace, that people keep flushing toilets and filling pools, and that California rainfall doesn't rise much above its average of 24 inches per year.
But note that five years of above-average returns haven't yet generated any groundswell of thinking that we're now in some New Era of above-average returns.
For example, when the researchers asked the MBA students about their likely salary package in their first job, the optimists tended to predict that their starting earnings would be higher than average for their peers--but the optimists didn't, in fact, end up with above-average starting salaries.