I'm guessing a lot of that water went underground into an aquifer.In 1861 the floods were so bad there was a 6000 square mile lake formed in the Central Valley.
Within a year or two, the lake was completely dry, and hasn't been seen since.
I'm guessing a lot of that water went underground into an aquifer.
They were pumping so much water in recent years due to the drought that the ground was sinking 2 inches per month in some areas - https://www.theguardian.com/us-news/2015/aug/19/california-sinking-groundwater-pumped-drought