Two words “eminent domain”. The government, both federal and state (depending on the state) can absolutely obtain your land with zero recourse. They’ll pay you for it, but you don’t get a choice.
What? There is absolutely recourse, such as "sue them and at a minimum tie the project up in lawsuits for years". Or "be furious and rally with lots of other furious land owners/interested citizens and vote the bums out" because focused single interests, even as minorities, often can exert a great deal of political influence in a democracy. Or even illegally resisting through various means, which might not affect this area of California specifically but is a real threat in some parts of the US.
Eminent domain has an important place and has be used well, as well as abused. But whether justified or not its use, particularly in modern, is frequently fraught with controversy and political/legal battles.
The power as written is pretty powerful and has only gotten more powerful and broad every time it's challenged in court. Since it's hard to argue that building a high speed rail isn't "public use", the only thing you'd be suing over would be the "just compensation" part.
I believe in that case, the government can take and use first, and you can lawsuit afterwards over how much money you think it's worth which really doesn't stall anything.
If the government can use eminent domain successfully take over land to give to private developers to build a mall, or even take it just to increase city revenues, it sure as hell can use it to build a train.