The problem isn't that we can't build _one_ desalination plant: we totally can, and in a reasonable time frame even. It's that a single plant is not enough for the scale of the problem. A decent size desalination plant can produce 50 million gallons of water a day, with the average household in California using about 50 gallons a way. So that's only a million households covered sorted. And while it'd be tempting to say "we're not replacing the Colorado watershed, we just want to supplement it", there is literally nothing left to supplement, that thing's running completely dry, fast.
So: there's about 13 million households in California alone, clearly we'd need at least 10 desalination plants: there is no way we can make that happen in less than several decades, with the main problem being the very thing we're trying to address: there is flat out not enough time to perform the necessary environmental impact assessment associated with building that many desalination plants all at the same time. Solving the fresh water shortage by destroying the entire western sea board would be insanity.
So yes: absolutely, let's build a desalination plant, it'll help la bit, just like forcing people to use less water will, but once it's up it's going to take a few decades before we can properly assess what damage it does (if any) to both the local environment and those directly connected through both static and tidal currents, before we can build another one.
So: there's about 13 million households in California alone, clearly we'd need at least 10 desalination plants: there is no way we can make that happen in less than several decades, with the main problem being the very thing we're trying to address: there is flat out not enough time to perform the necessary environmental impact assessment associated with building that many desalination plants all at the same time. Solving the fresh water shortage by destroying the entire western sea board would be insanity.
So yes: absolutely, let's build a desalination plant, it'll help la bit, just like forcing people to use less water will, but once it's up it's going to take a few decades before we can properly assess what damage it does (if any) to both the local environment and those directly connected through both static and tidal currents, before we can build another one.