I have thought about this for the last year and tried to learn as much as I can. Yes, it is expensive.

Does it matter at this point?

Most experts don't seem to think there will be enough precipitation over the next decade to refill existing reservoirs let alone replenish the almost wiped out aquifers. This isn't a case of 1 or 2 rainy seasons making up for what is lost.

If the US wants to continue growing into inhospitable areas and growing crops in areas where water is unavailable, serious work needs to start on desalination efforts.

It will be expensive. There will be an environmental impact. It will take years to build as the US no longer can do public works quickly.

Desalination is the only long term solution for the US west if you do not want to limit land use.

Israel gets 80% of it's water from desalination, it works out about $0.65 per cubic meter (tonne) so it's more expensive then literally falling out the sky but certainly affordable for a first world country...maybe even the US.