alt.hn

3/17/2026 at 6:43:53 PM

The Los Angeles Aqueduct Is Wild

 https://practical.engineering/blog/2026/3/17/the-los-angeles-aqueduct-is-wild

by michaefe

3/20/2026 at 4:44:28 PM

The norcal/socal divide caused by the river is funny to me. I grew up in LA, then moved to the Bay Area for college. In LA we never really talked about where our water comes from. But we were always 'in a drought' and always taught to conserve water.

My wife grew up in the Bay Area, and was told the same.

But her family is from Sacramento. Up until about 15 years ago, everyone in Sacramento paid the same for water (based on square footage of your home). There were no water meters. So they didn't conserve. They ran the sprinklers in 100 degree heat for hours, they washed sidewalks with water instead sweeping, and all the other things.

But when the meters came, her Uncle blamed SoCal for "stealing his water". He complained every month when the bill came about how he has to pay more now because of SoCal.

by jedberg

3/20/2026 at 4:58:29 PM

Owens valley, where LA "steals" water from, is on the eastern side of the Sierras.

NorCal, including Sacramento, is on the western side of the Sierras.

So unless they planned on pumping the water over/under the mountain range that surrounds it in every direction except for towards LA, that water was never available for any NorCal city to use.

by kenhwang

3/20/2026 at 5:45:47 PM

The California Aqueduct delivers water from the western Sierras through the Central Valley and to Los Angeles. This is likely what NorCal refers to when they say SoCal is 'stealing our water'.

https://en.wikipedia.org/wiki/California_Aqueduct

Would be interesting to see the relative amounts of use by LA and by agriculture in the Central Valley though.

by mutagen

3/20/2026 at 6:09:19 PM

SoCal does, yes; about half the water going through the SWP from NorCal, or ~75% if you include Bakersfield/Kern as part of SoCal (though most would consider it Central Valley).

But SoCal isn't only LA. LA itself gets a bit less than half of their water from MWP, which manages the water from the SWP and the Colorado. About the same amount it gets from the the eastern Sierras. These are supposed to drop to ~10% of LA's water supply as recapture/recycling projects complete.

Or computed the other way around, LA only has rights to ~20% of the water managed by MWD. Of course water supply, distribution, and rights are all blended and traded around all the time, but generally speaking it's not "LA" using up that water from NorCal, the consumption is significantly more from the cities and farms that came after.

by kenhwang

3/20/2026 at 5:59:29 PM

This infographic basically explains it:

https://www.ppic.org/publication/water-use-in-california/

tl;dr: Urban water use is tiny. In NorCal, the vast majority of the water flows unimpeded to the sea. In the Central Valley, most water is used for agriculture. Agricultural water use in any one of the 3 major basins in the Central Valley is more than all urban areas in California combined. Unsurprisingly, urban use is the primary one in the SF and LA areas, but the absolute totals are very small compared to total CA water supplies.

by nostrademons

3/20/2026 at 6:23:34 PM

Owens valley is basically dried up from the water that LA takes. It's interesting as you drive in the towns in the Valley and you see all the LA Department of Water and Power offices over 200 miles from Los Angeles. The courts had to force the LA DWP to quit taking too much water from the streams that feed Mono Lake as it was in danger of drying out.

by vondur

3/20/2026 at 6:31:10 PM

Yep, Owens valley is basically an environmental disaster created by LA. So in the grand scheme of things, buying water from NorCal is better than stealing from the Owens valley through antiquated water rights.

But really, California (and really the entire Western US) needs a water rights governance overhaul. Right now the focus is all on urban water use, which is practically negligible compared to the agricultural water rights usage.

by kenhwang

3/20/2026 at 9:32:50 PM

That's a money play too. Some of the best farmland in the world is now the endless subarban Boston->DC corridor.

We created the miracle on the desert, and billions were made in real estate.

by Spooky23

3/20/2026 at 7:54:51 PM

Much easier to tell Joe homeowner he's not allowed to have a lawn than to close down the country club. Where would the rich relax then?

by paradox460

3/20/2026 at 9:11:22 PM

The country club is also negligible compared to agriculture. Farmers are politically not an attractive punching bag though.

by ashdksnndck

3/20/2026 at 7:44:22 PM

It isn’t dried up, they maintain a certain water level in the various lakes.

by kjkjadksj

3/20/2026 at 5:24:40 PM

they are saying that LA takes water from sources which would otherwise drain into the sacramento and san joaquin river delta. The video from this post mentions the California State Water Project which takes water from the Feather River (Oroville Dam) and distributes it along the Western edge of the central valley South to Bakersfield where it is then pumped over the mountains both towards Los Angeles and further East to San Bernardino and Riverside. It provides way more water to SoCal than the two Los Angeles-specific aqueducts from the Owens Valley on the Eastern side of the Sierras.

by jlhawn

3/20/2026 at 6:58:57 PM

Old men yelling at the sky don't often seek rationality or nuance in their cries.

by dpe82

3/20/2026 at 7:00:38 PM

Yes, Norcal spent decades wagging fingers at SoCal about this. There were books like Cadillac Desert.

Meanwhile, San Francisco drinks clean glacier water that a valley in Yosemite was destroyed to provide this and they refuse to repurpose a downstream damn that has enough capacity to do it.

Physician, heal thyself.

by jsLavaGoat

3/20/2026 at 9:22:16 PM

Can you clarify what you mean by: “they refuse to repurpose a downstream dam”

California has insufficient water storage to meet demand, it’s not like we have huge dams lying around that we leave empty when there is water available to fill them.

You might be referring to Don Pedro dam - but we are already filling that up (modulo what we need to keep empty for flood control). SF has some contractual right they could possibly exercise to water in Don Pedro but that doesn’t magically result in California’s water supply being held constant if we stop storing water in the Hetch Hetchy. If SF gets the Don Pedro water, that means someone else that was going to get it is deprived.

Now, you could argue that the state can get by with lower storage because ag needs to consume less or more groundwater recharge or whatever, but that’s a different question.

by ashdksnndck

3/20/2026 at 8:01:51 PM

Crystal Springs isnt anywhere near Yosemite if that is what you are referencing. That being said it supposedly was gorgeous and almost as amazing before being filled with water

by Melatonic

3/20/2026 at 8:36:44 PM

Not Crystal Springs. Hetch Hetchy, the damning of which legendarily caused John Muir, the founder of the Sierra Club, to die of a broken heart.

by jsLavaGoat

3/20/2026 at 8:46:59 PM

It’s a nitpick but the words you are looking for are “dam”, “dammed”, and “damming”. Damning is a very different thing entirely.

by stouset

3/20/2026 at 9:32:34 PM

They both work, really

by CalRobert

3/20/2026 at 8:23:57 PM

They are referring to Hetch Hetchy.

by dontlikeyoueith

3/20/2026 at 8:02:45 PM

Looking at what Tehran is facing (not related to the war, water shortage), I'm wondering why california isn't investing in more desalination for SoCal, especially for LA.

I see some here:

https://lynceans.org/all-posts/status-of-desalination-plants...

But there are only a few in SoCal and they're for smaller communities like carlsbad or santa barbara. So it is there and it is working for some, why not more? naturally i assume it's because everything costs more at the coast.

by notepad0x90

3/20/2026 at 8:09:33 PM

There are environmental and financial concerns https://calmatters.org/environment/2022/05/california-desali...

I don't understand the financial concern at all. How could increasing the water supply increase the price? It only makes sense to me if the price is artificially low right now.

Environmental damage by a desalinization plant couldn't possibly be worse than overdrawing the acquifer -- the defacto solution.

by peterbecich

3/20/2026 at 8:33:08 PM

Building an industrial facility in california is much more difficult and expensive due to numerous regulations.

by daedrdev

3/20/2026 at 8:49:29 PM

> I'm wondering why california isn't investing in more desalination for SoCal, especially for LA.

Because California has plenty of water for residents. What California doesn't have is plenty of water for agribusiness.

And the agribusinesses do NOT want people paying close attention as all the valid solutions to water problems are basically "shut down agribusinesses in arid areas".

by bsder

3/20/2026 at 3:03:27 PM

Being from LA, I am used to a water system that works without needing power. I think most of CA is like that. It was a surprise to lose the water back east when the power went out during a storm.

by gorfian_robot

3/20/2026 at 4:14:44 PM

The only places I've heard of losing water during power outages are houses that use a private well (no power, no well pump), which would be the case anywhere. Municipal water systems may or may not use power to provide pressure, but are going to have generator power outside of the most severe outages.

by macNchz

3/20/2026 at 4:28:05 PM

Also, water towers. As long as the power isn't out long enough to deplete the tower.

by MrZander

3/20/2026 at 4:28:57 PM

I wonder if this was in an apartment building. We owned a condo in a 5 story (4+1) apartment building and because it was taller than the San Jose water system was built for, our building needed (electric) pumps to provide water pressure to the building (there were tanks on the roof). If we lost power, then we lost water.

Now that we have moved to a 2 floor detached home (also in San Jose) we do not have that issue, and everything is gravity fed.

by larkost

3/20/2026 at 4:40:16 PM

Do you lose water in the whole building, or just those apartments above the water-line?

by fhdkweig

3/20/2026 at 7:46:59 PM

Usually these relatively low height kinds of top-tank systems lose water for the entire apartment building, because there's one pump to raise the water to the tank, which then passively provides the pressure (usually through pressure regulators at each floor if I remember right).

Larger buildings tend to have multiple independent systems

by jaggederest

3/20/2026 at 5:03:57 PM

We happened to live on the top floor, so I don't have personal experience for the lower floors, but the communication on the (non official) group chat for the building always hinted that any water outages (we had a few non-power issues with the pumps as well) applied to to the whole building. But thinking back that could be an unfounded assumption.

by larkost

3/20/2026 at 3:43:55 PM

The LA water system is dependent on power as a whole. There’s many pumping stations along the various aqueducts.

by duomo

3/20/2026 at 6:19:15 PM

We do not lose water on the east coast when the power goes out

by tjwebbnorfolk

3/20/2026 at 9:37:39 PM

It depends where you are. Most cities in the Northeast you are correct. But coastal areas, big swaths of New Jersey and Long Island IIRC are definitely dependent on power. Towns with water towers usually pump it from the ground.

Alot of suburbs that can't or won't hook into city supplies will sometimes need more active measures to filter their water as well.

Sanitary sewers are heavily dependent on power.

by Spooky23

3/20/2026 at 3:48:15 PM

I know NYC doesn't treat their water at all, but LA doesn't either?

My city runs on surface water, so we have treatment and then pump to storage tanks. You would have to be out for quite a while to run the city out of water, though - the tanks are large.

by devilbunny

3/20/2026 at 3:58:29 PM

LA definitely treats the water. Both the surface water before consumption (I'd be surprised if any city doesn't do this) and the wastewater, for reclamation for nonportable use like irrigation, and for recycling back into the general clean water supply.

The aqueduct water is specifically purified by the Los Angeles Aqueduct Filtration Plant. That plant is gravity fed, but it doesn't operate without power.

LA just has the advantage of having mountains in the city, so it's cheaper building more elevated water storage so the capacity lasts longer during power interruptions (which are also not as common or extended as they are in the east). They will still eventually run out if they're not replenished by powered pumps.

by kenhwang

3/20/2026 at 4:34:17 PM

Where did you get that idea about NYC water being untreated? NYC treats its water. Chlorine is added if and when needed. Testing stations exist to evaluate water quality all around the boroughs, etc.

You can't have a city of millions of people and have the water be potable from the tap without testing and treatment

by simtel20

3/20/2026 at 5:12:26 PM

https://www.nycfoodpolicy.org/10-facts-you-may-not-know-abou...

> New York City’s water (including drinking water) is unfiltered, making it the largest unfiltered water system in the country. Were New York to begin filtering its water, it would cost the city approximately 1 million dollars per day to operate the filtration plant.

They have hundreds of sampling stations to check daily.

https://www.nytimes.com/2025/05/01/nyregion/nyc-tap-water-qu...

This causes some issues for observant Jews, because the water technically might not be kosher.

https://oukosher.org/blog/consumer-news/nyc-water/

https://www.nytimes.com/2004/11/07/nyregion/the-waters-fine-...

by ceejayoz

3/20/2026 at 5:30:26 PM

Ok, but unfiltered does not imply untreated. Maybe that's where they got the idea, though.

by andrewflnr

3/20/2026 at 6:25:46 PM

It is, indeed. I'd edit the post but... too late.

by devilbunny

3/20/2026 at 5:50:04 PM

It's largely unfiltered, but it is still treated for disinfection. Chlorination and UV is standard for NYC water, and its fluoridated as well.

by valarauko

3/20/2026 at 7:59:19 PM

Treatment is usually just the addition of chlorine and in some countries, fluoride.

Filtration isn't common.

by markdown

3/20/2026 at 4:45:46 PM

I know NYC doesn't treat their water at all…

EDIT: I'm a dork an grabbed the wrong URL. Changed URL to a PDF for lack of better.

A major metro doesn’t treat its tap water? Where on earth did you get that crazy idea?

<old URL deleted>

https://www.nyc.gov/assets/dep/downloads/pdf/water/drinking-...

I'll save some digging: "Even without filtration, the water is carefully treated to reduce the risk of harmful microorganisms."

by mikestew

3/20/2026 at 4:53:41 PM

He was talking about the drinking water that comes from the faucet, not the sewage.

The untreated NYC water has tiny crustaceans in it, which make it not Kosher, which is why thee bagels from a Jewish deli in NYC are so good. Go figure.

https://newsfeed.time.com/2010/08/31/drink-up-nyc-meet-the-t...

by jmalicki

3/20/2026 at 5:02:50 PM

Thanks for the correction, I should have looked harder at that page before posting. I've since corrected.

by mikestew

3/20/2026 at 8:01:21 PM

There's no way the water is untreated. Like just about everywhere else on earth, they will add chlorine when necessary.

by markdown

3/20/2026 at 7:58:04 PM

Odd. Most places use water towers to provide water pressure and have backup generators for the pumps that fill them.

by UltraSane

3/20/2026 at 3:33:49 PM

Sometimes it feels like the US has lost its appetite for grand structural projects like that. Maybe it’s just that I’m unaware of them and that impression is the result of survival bias, but given how impossibly hard it is to just build anything where I live (Seattle), I’m not so sure.

by strongpigeon

3/20/2026 at 4:03:25 PM

Seattle just got done building light rail tracks over a floating bridge.

It is an insane engineering achievement. A train literally running on tracks on a road that is floating on water!

by com2kid

3/20/2026 at 4:12:46 PM

Fair. Maybe I'm too much if the weeds of this because all I can think of is how much of a fight it was to pass ST2 and ST3 and how we haven't even started on the Ballard line despite voting for it in 2016 (10 years ago!) and how it might be delayed forever.

by strongpigeon

3/20/2026 at 8:05:30 PM

I get that it is neat but it's hardly the Hoover dam is it?

by dclowd9901

3/20/2026 at 8:26:43 PM

No, it's significantly more complex.

by dontlikeyoueith

3/20/2026 at 5:34:28 PM

No, it's not an insane engineering achievement. It's just a normal one, because nobody else has floating bridges, nobody else needed it. It's also years late and costs 10x more than it should.

It's also the wrong stupid technology. The trains are constrained on space because of the low-floor bullshit. It's the longest light rail in the country, it's too fucking long and slow. Even if we fully built out ST3 it can't handle more than ~20% of commuters. It can't be expanded with express tracks because it's built deep underground, so the commute is so much slower than the equivalent in other countries and will NEVER compete with the automobile except during peak rush hour. The northern stations are next to the freeway so over half the land that could be transit-oriented development can't be, and then what's left is devoted to parking anyway. Complete, total waste of a once-in-a-lifetime opportunity, built and planned by people who don't and won't ever use transit.

That 10x cost directly makes it so we can't build out our system properly and we keep building out car infrastructure because people would rather have a car and save 2 hours a day commuting.

by coryrc

3/20/2026 at 6:59:48 PM

> No, it's not an insane engineering achievement. It's just a normal one, because nobody else has floating bridges, nobody else needed it. It's also years late and costs 10x more than it should.

Your other points aside -

Doing something no one else has ever done is the definition of an engineering achievement.

There isn't a set of best practices. There aren't a bunch of off the shelf parts, there aren't any contractors who can help you out because they've done it a dozen times before. It is an original engineering challenge.

Pulling it off is by definition an achievement.

That said, 100% agree about the station placement. Heck the stations that are well placed were poorly designed, they should be profitable by including commercial real estate and residences, with the revenue from both going to Sound Transit to pay for the system.

But no, we didn't do that and I can't even get a cup of coffee, in Seattle, at our light rail stations.

by com2kid

3/20/2026 at 3:40:37 PM

I don't think you're wrong. Every time someone says we can't do high speed rail it makes me very sad. And as far as Seattle goes... my commute is substantially affected by the I-5 closures. It's somewhat shocking to me that we allow infrastructure to decay as much as we do.

I'd be happy about the light rail expansion if they weren't talking about delaying the Ballard line indefinitely. :(

by BryantD

3/20/2026 at 5:36:32 PM

The commute is slow because the light rail is slow. It's the wrong technology for commuter rail and there are too many stops. (I'm assuming you live north).

(more details: https://news.ycombinator.com/item?id=47457884)

by coryrc

3/20/2026 at 4:56:11 PM

Can't do highspeed rail because it's too impractical and expensive, while we're spending a west coast highspeed rail network worth of money on the least popular war in US history.

by zardo

3/20/2026 at 5:39:29 PM

California is spending the money and what they're building is useless (oh big passenger demand from Merced to Bakersfield, fuck right off with that) and costs 10x what China, France, Japan, etc pay.

by coryrc

3/20/2026 at 3:53:02 PM

Evidently tax cuts for the wealthy are more important than infrastructure.

by amanaplanacanal

3/20/2026 at 4:04:29 PM

Those projects would literally be impossible today with the environmental regulations in place, especially in California.

by rabid_0wl

3/20/2026 at 4:53:10 PM

If you watch the OP, you'll see that the construction of this aqueduct caused billions of dollars worth of environmental devastation. Rail all you want against regulations, but when an argument boils down to "I wish we didn't have to internalize all these costs and could just push them off on someone else", I'm not especially sympathetic.

by kibwen

3/20/2026 at 5:55:23 PM

LA has paid billions to remediate, but the actual cost is incalculable. Not sure who is "railing against regulations" but there are obviously downsides to heavy environmental regulations. Debatable if CA is striking the right balance.

by rabid_0wl

3/20/2026 at 4:34:13 PM

Certainly that’s part of it, but also just NIMBYism. Los Angeles were able to defeat the Owen’s Valley farmers back then, I don’t think they would be now.

by OskarS

3/20/2026 at 5:39:18 PM

We're literally right now building a huge high speed rail project that is planned to link san diego to san francisco through LA, bakersfield and fresno. Progress is made on it daily. https://www.youtube.com/CAHighSpeedRail

by schlauerfox

3/20/2026 at 9:42:29 PM

That may be true for some twisted definition of "building". Most people would say the money is simply being wasted by bureaucrats, consultancies, etc.

by baggy_trough

3/20/2026 at 7:48:38 PM

And when did that project start and how much has it cost and how far can you ride on what they've completed up until now?

by jimbokun

3/20/2026 at 6:01:23 PM

Progress is made on it daily? Great. How soon can I ride it?

by AnimalMuppet

3/20/2026 at 9:37:15 PM

Caltrain, from SF to SJ, is part of the California high speed rail system, and you can ride it right now. It's now electrified at 25KV, welded rail, concrete ties, and compatible with high speed rail. The Stadler trains are capable of 125MPH but are run slower because there are so many stations.

by Animats

3/20/2026 at 3:45:38 PM

It’s too complicated to corruptly make money off of a large project like that. It’s much easier to just buy a bunch of drugs and needles and give it to the methheads, or spend money on homeless while building zero homes.

by dogemaster2025

3/20/2026 at 8:19:37 PM

Am curious, how have the shade balls been working out in terms of maintenance, coating wear, leeched microplastics, containment (so they don't wind up in oceans), etc? In retrospect, did it make sense compared to the $250M or so uplift it would have taken to build a conventional roof?

by rkagerer

3/20/2026 at 8:37:51 PM

No way they could feasibly have built a roof over that reservoir.

by lazide

3/20/2026 at 3:37:52 PM

"Well There's Your Problem" on the collapse of the St Francis Dam, mentioned in Grady's video https://www.youtube.com/watch?v=hxLgM1vnuUA

Also I love when they refer to it as the "_First_ California Water Wars" in a grim realization of the future of water scarcity in the West

by z3ugma

3/20/2026 at 4:29:12 PM

There is no water scarcity in California, only misallocation. The vast majority of our water is heavily subsidized and used for agriculture, and a substantial amount of those crops are grown for export, yet agricultural exports makes up an insignificant part of California's economy.

We could end all California water scarcity talk today, with no impact to food availability for Americans, by curtailing the international export of just two California crops: almonds and alfalfa.

by hamdingers

3/20/2026 at 8:08:48 PM

In Arizona we grow alfalfa as well -- it's mind boggling to me that in places where water is so scarce we use so much of it on such a low value crop.

by dclowd9901

3/20/2026 at 8:29:34 PM

That alfalfa gets extensively exported as livestock feed... and alfalfa is literally mostly water by weight. So the arrangement is literally shipping out local groundwater in bulk to other countries.

by crooked-v

3/20/2026 at 4:54:14 PM

Anecdotally, my friend's grandma was an almond farmer. As they drove past a river in the Central Valley, she exclaimed "Why is there water in that river?! Those could be watering my almond trees!"

by SCUSKU

3/20/2026 at 5:18:50 PM

So why hasn’t that been done? Have some representatives and senators set limits on almond exports. Surely they wouldn’t be voted out in the next election given how farmers are outnumbered.

by kccqzy

3/20/2026 at 5:31:35 PM

Because farmers are making money off of exporting and have significant lobbying power

by patmorgan23

3/20/2026 at 9:27:29 PM

Bold of you to assume that ordinary voters matter more than Billionaires like the Resnicks of The Wonderful Company.

by markdown

3/20/2026 at 5:24:59 PM

Almonds are climate-appropriate product and valuable. Alfalfa can cheaply be grown off rainwater in the Midwest and it alone frees up sufficient water.

by coryrc

3/20/2026 at 6:49:56 PM

The problem is alfalfa is expensive to transport (heavy due to desired moisture content). So while it can be cheaply grown in the Midwest, it can't be cheaply transported from the Midwest to where buyers of alfalfa are (typically overseas).

Alfalfa is also a staple for crop rotation, so any farming operation will still grow some alfalfa to maintain rotation for good soil health (or during bad condition seasons since it's hardier to poor conditions and not a permanent crop).

If alfalfa cannot be exported (through policy or economic conditions), the low price attracts more livestock production in-state (which would be even worse for water use).

Those things makes it a hard crop to target for sustainability and export.

by kenhwang

3/20/2026 at 4:52:37 PM

to put this to numbers... the exports are just about 0.5% of california's GDP. so yeah pretty much a rounding error.

by weaksauce

3/20/2026 at 6:34:59 PM

0.5% is a far cry from a rounding error..

by chrisrogers

3/20/2026 at 6:53:02 PM

0.5% is like the literal definition of a rounding error.

by panzagl

3/20/2026 at 8:34:23 PM

My favorite part of this video is where they divert and dry up one lake, and then build two reservoirs further downstream.

by hnburnsy

3/20/2026 at 6:58:48 PM

There's a poem carved into the stonework of Washington Union Station, part of the art installation The Progress of Railroading from c. 1909:

the old mechanic arts / controlling new forces / build new highways / for goods and men / override the ocean / and make the very ether / carry human thought

the desert shall rejoice / and blossom as the rose

by retrac

3/20/2026 at 3:15:17 PM

I was surprised to find out it was largely uncovered, though I guess it probably makes it much cheaper to construct. I usually think of aqueducts as pipes or tunnels, like Persian qanāts. I wonder how much water is lost due to evaporation.

by rimunroe

3/20/2026 at 4:47:29 PM

There's some testing to see how covering open irrigation canals with solar panels which would reduce evaporation and generate power

> Their analysis found that putting solar panels over the 4,000 miles of California’s open canals could save up to 63 billion gallons of water annually

https://www.universityofcalifornia.edu/news/solar-panel-cove...

by jonathonlui

3/20/2026 at 6:48:52 PM

> could save up to 63 billion gallons of water annually

To put it into perspective, 63 billion gallons is 193340 acre-feet, which is 0.5% of california's water use (a bit under 40 millions acre-feet). That's a tenth the water consumption of lawns, which is 1/15th the water consumption of agriculture.

by masklinn

3/20/2026 at 9:18:23 PM

Or about 4 hours of Mississippi River discharge.

by Rapzid

3/20/2026 at 9:29:02 PM

But how many football fields?

by markdown

3/20/2026 at 4:56:20 PM

Thanks! I forgot that article, but now I remember that I read or skimmed it when it made the rounds last year. It's actually where I first learned that the aqueducts were uncovered!

by rimunroe

3/17/2026 at 11:49:08 PM

Nice picture but I've never seen the water anywhere near blue like that.

by anjel

3/18/2026 at 4:23:18 AM

That's a youtube thumbnail. I believe it's been altered, which also explains the strange brown substance that looks out of place.

Most of the video content has the correct coloring, from my experience observing the aqueduct.

by Supermancho

3/20/2026 at 3:51:13 PM

I think it's edited to look like water he uses in his garage demos.

by w4der

3/20/2026 at 2:34:50 PM

I wonder at what point the up-front costs of massive desalination would overcome the (often hidden and externalized) costs of projects like this.

by bombcar

3/20/2026 at 2:37:08 PM

> the up-front costs of massive desalination

Desalination is dominated by operating costs.

by JumpCrisscross

3/20/2026 at 3:31:50 PM

Correct it's massively energy intensive to filter the salt out the newest best ideas still use ~2 KWh/m3 of water and that's a lab system in perdue that batches the process instead of having it run continuously which is why current RO desalination systems require so much energy.

by rtkwe

3/20/2026 at 6:55:22 PM

For a real world comparison, the Perth desalination plant claims ~4kWh/m3.

by masklinn

3/20/2026 at 4:38:43 PM

A scaled down perspective is….

The most efficient commercial desalinator for boats is 32 Watts a gallon.

by detourdog

3/20/2026 at 4:48:49 PM

Do you mean 32 Watt-hours / gallon?

by fhdkweig

3/20/2026 at 5:16:36 PM

Hard to say. The spec sheet calls out 4 Amps for the 12 Volt system or 32 Watts for a single gallon.

by detourdog

3/20/2026 at 5:23:30 PM

If it includes the time it takes to produce that gallon, there would be enough information to do the energy calculation.

by fhdkweig

3/20/2026 at 5:27:38 PM

I guess it would be 48W/h as it makes about 1.5 gallons an hour.

by detourdog

3/20/2026 at 5:31:03 PM

Which to scale back up and complete the comparison to the state of the art in lab "batch reverse osmosis" systems I was originally talking about that's ~12.7 kWh/m3.

by rtkwe

3/20/2026 at 4:32:18 PM

California pays other states to take its excess solar energy. Power for a project like this isn't the issue, actually building the system is the issue.

by smm11

3/20/2026 at 5:50:37 PM

They wouldn't if you switched just Urban water use from natural sources to desalination. To do that you need to replace the ~5 million acre feet of water, ~6,167,400,000 m3, that goes into the Urban bucket which is all of the water used to keep people alive, clean, and all industrial uses of water. [0] That comes to ~ 12BkWh of energy needed to scale up batched reverse osmosis to take over just the life and job required water needs which is about 25% of the total solar power generated in all of 2025 via grid-scale solar farms. CA does export some during the day due to excess solar but is still a net importer of power.

[0] p2 of https://cwc.ca.gov/-/media/CWC-Website/Files/Documents/2019/...

by rtkwe

3/20/2026 at 6:17:29 PM

Those are the numbers I was looking for - that means that (ignoring build-out costs) total desalination for CA would be on the order of 10% of the 3 gorges dam yearly output (max).

by bombcar

3/20/2026 at 6:30:40 PM

Using a system that's currently in a lab scale only and ignoring other energy costs like moving the water to the plant, mixing the briny output back down to acceptable levels, and then pressurizing the system to replace the gravity fed design it currently uses.

For a rough estimate for replacing agricultural uses too ~6x that urban figure at least then weep at the amount of pumps you'd need to bring that water up and inland to the farm lands from the coast. At least for replacing urban use most of the population lives on/near the coast where the water would be produced.

by rtkwe

3/20/2026 at 8:02:05 PM

Farm use is by far the biggest, but "taking" water from the inland empire and dragging it to LA is also a cost.

But all of this is firmly in the "we could do it if we really wanted/needed to" not "needs more energy than the sun will produce in its lifetime".

by bombcar

3/20/2026 at 5:41:11 PM

> California pays other states to take its excess solar energy

Intermittently. Essential services like water (with expensive fixed costs) aren’t a good fit for absorbing variable supply.

> Power for a project like this isn't the issue

California has the country’s most expensive power [1] in part due to policymakers constantly assuming it’s free.

[1] https://www.electricchoice.com/electricity-prices-by-state/

by JumpCrisscross

3/20/2026 at 4:55:17 PM

As long as we don't try to hide and externalize the cost of all the hyper-saline brine management that comes with desalination.

by kibwen

3/20/2026 at 6:18:39 PM

We can store it in the remains of Owens Lake ;)

by bombcar

3/20/2026 at 2:58:05 PM

I don’t think the brine pollutant issue has been meaningfully solved. You are also now pumping water inland uphill the whole way.

by kjkjadksj

3/20/2026 at 3:48:23 PM

For usage where the water mostly returns as sewage, is treated and then returned to the ocean, you can just dilute the brine with the treated discharge and then it returns at basically the original salinity.

by SoftTalker

3/20/2026 at 4:14:10 PM

It is common now for treated discharge to be sent to a discharge lake/leach wetlands so it can be used to replenish groundwater supplies.

by kenhwang

3/20/2026 at 4:10:40 PM

Growing up in LA, I was fascinated as a kid watching the water flow down this aqueduct. Anytime we drove by it on the way to Magic Mountain, I'd hope that it would be a water-on day.

by mjamesaustin

3/20/2026 at 4:44:27 PM

My dad lived in Palmdale, my mom lived in Glendale. I made that trip a LOT. It's cool when it is all lit up with the colorful lighting.

by whalesalad

3/20/2026 at 5:15:49 PM

For anyone interested in a deep dive, I recommend the book Vision or villainy: origins of the Owens Valley-Los Angeles water controversy.

by TipsForCanoes

3/20/2026 at 5:12:22 PM

Some say the LA aqueduct saved Owens Valley from development. (I’m sure the old timers out there would have a different opinion)

by TheGrassyKnoll

3/20/2026 at 6:49:13 PM

> (I'm sure the old timers ...

Something along the lines of "we fought tooth and nail to save LA from development"?

by bell-cot

3/20/2026 at 5:00:41 PM

I remember hearing years ago that this aqueduct was going to be shut down and then it just... never was? Does anyone else recall that?

by wolandomny

3/20/2026 at 3:52:16 PM

I really dig the editorial viewpoint of this article. New journalism style meets fun facts about engineering.

by babblingfish

3/20/2026 at 2:47:22 PM

If anyone wants a deep dive on this subject: https://en.wikipedia.org/wiki/Cadillac_Desert

by KerrAvon

3/20/2026 at 4:16:35 PM

Came here to post this. Dam good book on the shifty maneuvering that resulted in the Owens Valley Diversion and ultimately the population center that is LA.

by jackconsidine

3/20/2026 at 4:27:53 PM

That bit of history can't be left out. The engineering is super cool though.

by hvb2

3/20/2026 at 2:45:47 PM

The California aquaduct system is an engineering marvel.

by hparadiz

3/18/2026 at 12:35:33 PM

Really enjoyed watching that. Good luck with water LA.

by 3happyrobots