California is the 5th or 6th biggest economy in the world (depending on the exchange rate), not the 10th. That’s bigger than France or Canada and about even with the UK. We also have the 35th largest population of any nation.
As for water, remaining part of the US doesn’t actually do anything to help our water problems and the Colorado river isn’t a viable long term water source anyway as the combination of climate change and growing populations upriver from us are drying it up. The only we California can solve our water woes and gain real self sufficiency is via large scale investments into creating better desalination tech — investments we can’t afford to fund when we’re being forced to spend north of $50 billion a year subsidizing the red states that hate us. Independence is literally the only chance we have to gain water security.
Californian independence isn’t just a realistic option, it’s the only realistic option. Staying part of the US is a dead end. Check out http://californianational.party if you agree.