There are more than enough people in CA to maintain the population growth rate with minimal or even no immigration. Immigration, legal or otherwise, has dropped off greatly in CA because, among other things, it's just too expensive to live here even under bridges if you're making minimum wage or less.

The Bay Area has also seen net out-migration in some job categories (like LA, and to a lesser extent San Diego) because of the cost of living (as well as the odd regulations and fees, which aren't as bad as some claim but still, they exist which generally isn't the case in places like Texas; simple existence of regulation is important in the race to the bottom) - unless you're one of the techies you can't afford the rent, and even there the H1Bs and entry-levels have to share apartments in large groups to break even. Or commute, of course; the prices in the Central Valley and Inland Empire, in places convenient to freeways or transit to the Bay Area, have been rising quickly in the last year or 2 as "drive to qualify" becomes a thing again, which pinches the generally lower incomes of the people who live and work there. Everybody b*****s about the traffic and the crowds on BART and Muni because there are so many people there trying to make money while they can. Oh well, what goes up will come down, and this bubble shows all the signs of approaching the point of catastrophic leakage; best not to be there when it does.