Actually, I think the author made that point - that this is the worst drought in the history of the state of California - but California has only been a state for a little over a century and a half. The author makes the point that the 20th century saw an unusually high level of precipitation for the region. Using proxy data (growth ring data from old-growth trees, etc.), it becomes clear that drought is the normal condition for California. In fact, in the last millenia or so, California has had droughts that lasted decades, and in one case, centuries.
Same with using ancient TX Cypress: in the 1500s, there was a *hundred* year drought. That was horrible to have in the back of one’s mind during this 5yr drought.