[bdamm]

California has already invested a lot into reservoirs. In fact, as a pilot, I recall noticing that nearly all lakes in California are actually man-made reservoirs. I doubt there is much room left for economically building more; all the easy ones have been taken, and more. Surely the cost benefit of just investing a lot into desalination must be getting close.

[kyboren]

Well, the California Coastal Commission put the kibosh a few years ago on a decades-long desalination project: https://calmatters.org/environment/2022/05/california-desali...

I haven't heard of any new desalination projects making headway since. The cost-benefit analysis may favor it, but I'm not sure the politics do. Of course, those politics will probably change in 10-15 years in our next big drought cycle, and then we'll really wish we'd gone forward with more desalination.

[kriskrunch]

Doheny was approved shortly after the Huntington Beach desal plant was killed. Update from last month: https://www.ocregister.com/2025/11/26/landfill-trash-could-h...

Poseidon currently runs a desal plant in Carlsbad. My understanding is that the water the plant releases into the ocean requires exemptions for how concentrated it is. Additionally, the plant draws plankton filled water. Not really what we want in California.

There are better desal solutions out there like OceanWell. They have a deep water desalination solution that solves many of the problems of conventional desal. They just signed a project in Nice, France in the past few days. Also, they are working with the city of Las Virgines over the past few years.

If I remember correctly, the new desal plant in Doheny has a slightly different approach to draw water in from beneath the sand, using the sand as a prefilter. But I'm not sure how that works better than drawing water in from near the surface. I can't imagine how the plankton can possibly escape the suction forces drawing them into the sand.

[kyboren]

I wasn't aware of the Doheny project, thanks! But it seems that that project timeline is at least as long as the one CCC killed.

With these kinds of timelines and that kind of regulatory risk, I don't think large-scale desalination is going to fix California's drought issues, regardless of whether it could.

[aidenn0]

We only have one because the Coastal Commision issued one for a plant around 1990 in a previous drought. The permit was maintained through to the current drought, at which point the Coastal Commission tried to get it shut down, but they lost since it was already permitted. Note that maintenance on the plant during the wet years was contentious; I don't know how it polled, but there were vocal people complaining about it, since it was barely used. Had those people prevailed, water would have been much dearer in the most recent drought.

[al_borland]

Desalination must be insanely expensive; I’m always shocked it wasn’t done decades ago.

Considering California always seems to have power and water issues, I’d think combining these things would make a lot of sense. Some of these exist and there seems to be a fair bit of research in the area. I have to image at some point that will be the direction California would need to go. Of course, if they are all-in on solar and wind, then maybe not.

[thaumasiotes]

> Desalination must be insanely expensive

It isn't. Mostly there are environmental concerns.

[nandomrumber]

Prove it.

Show us the data.

What is the price of desalinated water vs water that literally falls from the sky.

They both need to be chlorinated and piped to the end user, but desalinated water is typically at the wrong end of existing delivery infrastructure to take advantage of it.

And irrigators often have things like God deliver much of their water via rain, rivers etc.

So it stands to reason that desalinated water must be much more expensive.

Did reverse osmosis suddenly become energetically inexpensive while I wasn’t paying attention?

Did we build a bunch of nuclear power plants by the coast to use the waste heat for flash distillation?

Did brine disposal suddenly become a trivial issue to solve?

[devilbunny]

> nearly all lakes in California are actually man-made reservoirs

This is sometimes true even in much wetter states, though. I recall being thoroughly surprised to find that out that Virginia (!) has only two natural lakes, one of which is basically just an open area (though a large one) of the Great Dismal Swamp.