Experts say it's the worst the state has seen in 1,200 years.
The experts he's referring to are probably cited here.
http://www.nytimes.com/2015/04/14/science/californias-history-of-drought-repeats.html
The actual data shows two periods of megadrought in the last 1200 years, one lasting 150 years, the other 2000 years. This one is four years old.
Moonbeam was governor 1,200 years ago. He is the source of the data.
There was a 2,000 year drought in the past 1,200 year?