The warming of the world and melting of the polar ice caps led to a sea level rise of 75 metres. California was able to save the Bay Area and Central Valley from flooding by building four massive dams; two to the west of Santa Rosa, and two in San Fransisco. The cities of Gilroy and San Luis Obispo were also saved by three additional dams, though many debate to this day whether it was worth the cost. Nevertheless, the state mourned the loss of Salinas, Santa Barbara, Los Angeles and San Diego among others.
On the bright side, things are looking good for California - it's still at the top of the United States, both economically and demographically. The Bay Area has swelled to a cramped 16.9 million people, while Central Valley still manages to somehow pump out enough food to feed a good portion of the state and the country. The state has become even more diverse ethnically, with millions of Asian, Hispanic and White immigrants fleeing sea level rise.