The Los Angeles Aqueduct Is Wild | Hacker News Reader

The Los Angeles Aqueduct Is Wild

practical.engineering

414 pointsmichaefe208 comments

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.

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.

LA also gets water from the state water project which does come from northern california: https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Ca...

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.

The CWP is designed for robustness, on top of delivery. Those aqueducts you're pointing to that feed into the municipal portion of the Inland Empire are frequently empty because the IE has it's own (mostly) self-sufficient water store (the San Bernardino Mountains). They exist in case there is a point in which those regions need water fed in. You can literally just drive down to them at pretty much any time through the year and see that they're dry.

Additionally, if you're focused on the 6% (out of 11% total) water allocation that goes towards supporting the infrastructure of 22million people over the 50% that goes into non-optimal agriculture (almonds, for instance) in-between the two...then you're missing the forest for the trees, my friend.

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.

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.

Not just agriculture but highly water intensive agriculture like almonds. Also I read that a lot of laws about water in some US states contain so many grandfathered clauses that few people 'control' a lot of water use, not sure how much.

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.

The Los Angeles Aqueduct delivers water to LA.

The California Aqueduct is used for farmland in the central valley.

Two different things.

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.

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.

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?

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

It’s funny how the above comment reveals exactly why the problem is politically intractable.

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.

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

The lake is completely dried up. https://en.wikipedia.org/wiki/Owens_Lake And other lakes in the area are in really bad shape.

I disagree I drive through there every winter and the lakes are very large. The ecology of the valley is dry but nowhere near as dry as say the mojave just to the south.

Mojave was a desert. Owens Lake was huge. Your comparison doesn't make sense

What natural lakes in the region are still "very large"?

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

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.

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

They are referring to Hetch Hetchy.

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.

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

They both work, really

Not really inaccurate in this case, though. It's a huge loss.

Thank you for that grace, it was totally just a typo. And when I re-read it I was embarrassed, but your putting it this way gave me a chuckle.

Yeah but the Sierra Club enthusiastically believes that infill housing is evil because a shadow falls on a corner of a park used by underserved minorities. So one must assume that the environment is not anywhere near the top priority for them.

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.

I grew up in Sacramento and I remember when my parents were had a flat rate water bill. Those were the good ol' days!

It frustrates me how everyone moralizes water use rather than accepting that free markets allow for people who are simply willing to pay for it. For example, if you live in Sacrmanto and don't have a pool, you're just doing it all wrong (in my opinion, of course).

I watched my friend's family farm in Modesto flood their fields to irrigate them. No meter, just a valve off the canal and they pay a flat rate. So it offends me that my shower head is legally required to restrict it's flow. Or that neighbors decide that a pile of rock in the front yard is "better for the environment" as it radiates heat on a 105°F day...

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.

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. :(

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

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.

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.

There are no environmental impact studies on wildlife when you drop a bomb.

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)

My commute is via car. The light rail will not speed it up, but I may do it anyhow because it's more relaxing.

My point is that closing two lanes of the interstate for over a year is a failure of maintenance, rather than anything about light rail vs. driving.

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.

You mean, like NYC Water Tunnel #3? https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No....

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!

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.

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.

> 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.

I said it was, just not an "insane" one. It's not the Hoover Dam. Trains get on to boats all the time. It's innovation.

Oh yeah, and we hamstring ourselves because every extra property can only be used for "affordable" housing and we paid top dollar for it, then limit how much it can be used and tie up prime property which could have been used for more purposes. Gee, why is everything so expensive!?

> Oh yeah, and we hamstring ourselves because every extra property can only be used for "affordable" housing and we paid top dollar for it, then limit how much it can be used and tie up prime property which could have been used for more purposes. Gee, why is everything so expensive!?

Yeah everything surrounding what sound transit was forced to do with their finances sucks, which is why I have a lot of sympathy for the people trying to run ST and maintain its budget.

Everyone complains ST is bleeding money but the voters passed the laws forcing the finances to be terrible.

But every time I post that Seattle needs to dramatic loosen up building restrictions, it pisses everyone off.

Everytime I say things like "we should just do what cities running a good budget and that have affordable housing are doing" people get upset.

The curse of being an engineer. "Do the thing that makes the numbers work out" is rarely a popular opinion.

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

No, it's significantly more complex.

May be more complex but it's less audacious.

The water systems for LA and San Francisco are really quite audacious even if they have less technical complexity than floating rail.

I've built ML systems way more complex than any of these but it's still way less ambitious and audacious.

More complex for less benefit is just losing two different ways.

It's not exactly brain surgery, is it?

https://www.youtube.com/watch?v=THNPmhBl-8I

The achievement is the speed the train can run at. Trains going over the old floating railway bridges that were part of the Milwaukee Road had to slow down dramatically to, iirc, 6 mph.

Of course those were first built in the 19th century.

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

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.

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.

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.

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

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

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.

If you are claiming that Caltrain is part of the grand high speed rail system, you are literally being taken for a ride

The track is. That's how the SF connection is supposed to be made.

The initial segment in Central Valley has current date of 2032. It depends on if federal government restores funding or if California has to fund itself.

Phase 1 from SF to LA is estimated for 2035-2040. They might do end-to-end service before that with existing tracks and slower speeds, especially from Palmdale to LA. The SF and LA segments require tunneling to get over the mountains.

What's notable about the initial segment is that it parallels (and thus duplicates) an existing Amtrak service between Bakersfield and Merced. So the initial operating segment gives us zero new destinations by rail.

But, hey, you'll be able to go really fast between California's 6th and 80th largest cities!

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?

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

Rejoice. It will be the world’s slowest and most expensive “high speed” rail.

So slow, in fact, many countries have faster regular rail.

This is a joke, right?

Comments like these make me think, wow this place is no better than Reddit

The grand projects the US has embarked on have been completed using unethical means and without regard for real environmental consequences.

also they were completed during a time of much less housing density and eminent domain laws were more powerful - even getting a railroad setup nowadays costs billions because of land purchasing

This particular grand structural project was never a good idea, as the video describes. So it might not be the best basis for comparison.

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.

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.

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

As part of the contract for construction, the county or city must buy a certain amount of water every year.

Because desalination is not economically feasible, the water is more expensive and this extra subsidy raises the cost of the water bill.

This is how it works for the facility in San Diego County.

Building a desalination facility is economically hard to justify because the break-even point seems far away. It also assumes the state won’t eventually create a state-wide solution, which would benefit from a state-level economy of scale that a city/county effort might not.

> It also assumes the state won’t eventually create a state-wide solution, which would benefit from a state-level economy of scale that a city/county effort might not.

How would a state-level solution to who deserves water more benefit from economies of scale? This is about as core of an example of where you don't want central planning as you can find.

Water is normally "free" from mother nature. Desalinated water is not free as it cost energy to get the clean water. Even if there's a pump to get water from aquifers into the water system, that still rounds to free compared to the cost of running a desalination plant.

That is why I said "artificially low." As there is a water shortage, the current price should justifiably be higher. Instead we will simply run out or damage the acquifer by saltwater intrusion.

> 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".

people are always trying to conserve water, and droughts have been a plague for the past few decades. Even if the agriculture is taking up all the water, it doesn't change how water scarcity is a a very real part of socal life. You don't have to shutdown agriculture elsewhere, and it is a vital part of california's economy, that's just a lazy solution. I can get behind getting the agriculture industry to finance partly the desalination plants so they can free up the fresh water via the aqueduct.

In the unlikely event california becomes independent, water rights will be a big deal too, those natural water sources won't be so reliable without nevada's cooperation.

> You don't have to shutdown agriculture elsewhere, and it is a vital part of california's economy, that's just a lazy solution.

Agribusiness is under 2% of the California economy and an even smaller employer. You could wipe it completely out and the state would barely notice.

And nobody is saying to wipe out actual food production. Mostly people want to stomp on things like growing and exporting alfalfa (which is effectively exporting water for all intents and purposes).

> droughts have been a plague for the past few decades

Droughts have been a plague forever. Quoting Steinbeck from East of Eden:

“During the dry years, the people forgot about the rich years, and when the wet years returned, they lost all memory of the dry years. It was always that way.”

> In the unlikely event california becomes independent, water rights will be a big deal too

This is all hypothetical of course but the logical eastern border of an independent state centered in what's now California would be near Denver for precisely this reason.

I’m in a rare community in Southern California (part of north county San Diego) where my water is 27% from the ocean (10% for rest of San Diego county).

It’s cool. Still totally hard and makes everything fail early.

Because the economics of desalination require locking in long term purchase/production rates at prices that dwarf current and other sources of water. SD's Poseidon desal is projected at ~$3.7k per acre ft for 2026 whereas SDCWA SWP water is ~$1.5-1.9k acre ft. Leak fixes, groundwater recharge, local aquifers, water banking, potable reuse, etc. are all more economical means of bolstering water supply.

A big factor in determining desalination placement in the region are the groundwater basins. Limited size and availability makes the case for desalination as means for resiliency. Another is that situating adjacent to power plants so as to use their already coastally degraded intakes/outfalls. Doheny is to use subsurface slant wells for intakes, but it's also lower output too.

As for LA. they're working on getting their potable reuse plants/projects up and running. The largest indirect potable reuse plant in the world has been operating in OC for ~18 years. Lower operating costs than desalination, reduced wastewater discharge, and reduced coastal impact.

that's very insightful. But if I can dive a bit deeper, why can't desalination be made at a grander scale? why aren't desalination plants trying to fill up artificial lakes for example, where those lakes are also being topped-up with reused potables. Would it help if there were much larger nuclear powerplants in the desert that take in salt water via an aqueduct from the sea and send back fresh water to artificial lakes, depositing the waste into the desert? Salton sea might be a good enough spot in socal for example, where it is already toxic and salty.

The few times I've been to the Salton area, I was amazed at the agriculture in the middle of the desert, including things like citrus plants, despite smelling the stench of salton from there. There are various lakes that dry up all the time like big bear, what would it take to keep such basins capable of sustaining fresh watter topped up with desalinated fresh water, instead of directly consuming it? In other words, making desalination an upstream element, with the goal of resisting drought overall, not just immediate fresh water supply.

I've ever wondered about places like death valley, if the elevation there is so low, is it easier to build geothermal plants that could desalinate at a greater rate there?

And since I'm asking dumb questions already, if an aqueduct to LA is possible at a 4 hour driving distance, then I know it would be costly, but is it that impractical to build an aqueduct from the great lakes, which have no shortage of fresh water, and evaporation loss could easily be recouped by the sheer volume of available fresh water supply.

The Owens River source for LA is so good because it’s basically a continuous gradual decline from the source to the city, requiring no pumps.

Pumping is very energy intensive. At around 2000-3000 ft the energy needed to pump fresh water starts to equal the energy needed to desalinate the same amount of salt water.

Even if it’s just going up then back down again like the Tehachapi Mountains only like 1/3rd of the energy can be reclaimed.

The US needs a national water grid.

It would pay for itself after a few flooding events where were are able to redistribute the water more quickly. It also provides clean energy storage.

I've posted about it before with links to the studies but it usually just starts an argument by people worried the rest of the country is going to steal their water...

It seems like the least efficient way to solve the problem. Theres lots of water in many places in the US, if water is just allowed to be priced by how scarce it is in California, maybe people will move to a place where it’s not such a big deal.

This is the sort of low quality reply that made me think twice about commenting. Every time I mention it it's another set of poor quality, no thought, drive by responses and downvotes.

https://www.osti.gov/biblio/963122

Why do you think it's good to let the productive agricultural land of CA lay fallow? Why do you want areas in the east to go without proper flood control? Why do you think national food security is not a priority? I could go on... Read up on it if you like, or don't. Whatever.

I’m not a fan of people who say a comment is low quality because someone disagrees with them. I’m not going to engage any further with this discussion.

Disagreement is not the reason. You responded that you thought it was preferable to depopulate the most productive state in the nation. Come on man.

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.

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

Some of the aqueducts that deliver some of the water to LA do rely on pumping. But, the Los Angeles Aqueduct, which is the subject of this post, does not. The LA Aqueduct is entirely gravity driven, and under normal circumstances it is sufficient to supply LA's water needs.

Another nitpick is that California's various aqueducts are net producers of electricity (i.e., after accounting for pumping), so, while some of them do rely on electricity, they do not require an external source of power to operate.

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.

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.

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

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-...

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

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

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

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

Filtration isn't common.

Settlement, however, is fairly standard in surface supply.

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?

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."

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...

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

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

You linked to wastewater treatment, not drinking water. Wastewater is definitely treated in NYC.

Tap water is treated (UV and chloride disinfecting), but is largely not filtered: https://en.wikipedia.org/wiki/New_York_City_water_supply_sys...

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.

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

Apartment buildings often have pumps to increase pressure in the basement. Without power, the higher floors lose water.

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.

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

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.

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

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

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.

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

Why is that picture an extreme recolor of the original?

https://images.nebula.tv/5ba7e541-f57c-44cc-a91d-6a89bad158d...

To make people click.

Thank you, I was so confused by the obvious clickbait! I love Grady's videos, but yikes.

I said this in another comment, but I feel it's edited to look like water he uses in his garage demos with that blue glitter.

"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

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.

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

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

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

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!"

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.

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

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

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

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.

> it can't be cheaply transported from the Midwest to where buyers of alfalfa are

Trains.

Alfalfa isn't the only alternative, and they should switch to higher-value crops anyway. They would if they had to pay for water. We simply need to charge everybody for water usage.

The problem is alfalfa is a high value crop and a water efficient crop relative to value.

So as water/weather gets more unpredictable and beef/dairy rises in price, alfalfa becomes even more attractive to grow.

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.

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.

I hear about the almonds a lot. Are they more water-intensive than other tree nuts? Are they not commonly grown elsewhere in the world? All I really know about them is that they seem kinda nice, but not really worth the cost.

Also this https://youtu.be/5erVH-zk7Uk?si=kDEFEtltdyhp6Nen

I was in Owens River Gorge last week, it's a very interesting place. It has some of the tallest single pitch rock climbing in the world, sometimes requiring 80M ropes: https://www.mountainproject.com/area/105843226/owens-river-g...

The Owens river gorge has the highest concentration of sport climbs anywhere in North America, but there's not much variation, they're mostly edge ladders on weirdly slippery rock.

Not far away are the world's most photogenic boulders, the Buttermilks, and when I visited (from Canada) I was surprised to find that the boulders are on LA municipal property and the pipe that takes Owen's River's water over the Sierras is nearby.

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

Or another kind of take:

https://www.imdb.com/title/tt0071315/?ref_=nv_sr_srsg_0_tt_8...

(Chinatown)

Or another kind of take:

Land of Little Rain by Mary Hunter Austin

https://www.goodreads.com/book/show/91707.The_Land_of_Little...

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.

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

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

> the desert shall rejoice / and blossom as the rose

Or, rewritten for the Los Angeles Aqueduct:

the desert shall wither / and blossom in a plume of dust [1]

[1] https://www.latimes.com/environment/story/2025-06-19/owens-v...

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

I love Practical Engineering. Grady Hillhouse's enthusiasm for engineering shows through brilliantly. Being a graduate engineer, I've learned a lot from his videos and transcriptions. Well worth browsing practical.engineering.

PS: and it is NOT about software engineering LOL!

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.

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...

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!

> 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.

Or about 4 hours of Mississippi River discharge.

But how many football fields?

A football field is 1.32 acres, so it's 146470 football-field-feet.

Does anyone know why there's been a bit of a surge of videos/articles about this? Or am I just getting Baader-Meinhof ed?

https://www.youtube.com/watch?v=GeYvNkaLAqA

https://www.youtube.com/watch?v=aGNE-xVk8OE

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?

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

2020 update: https://wateroperator.org/blog/featured-video-why-are-960000...

Just a quick plug for Cadillac Desert. People don't realize how fragile the urban areas of Coastal California are. We should.

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

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

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.

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

NYC aqueduct from the Catskills is wild too, especially if you like the effect on NYC pizza and bagels.

Great articles have been written on the engineering but I like this one from 1909 showing the perspective of the time:

https://www.catskillarchive.com/rrextra/dnaque.Html

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

> the up-front costs of massive desalination

Desalination is dominated by operating costs.

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.

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.

> 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/

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/...

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).

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.

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".

A scaled down perspective is….

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

Do you mean 32 Watt-hours / gallon?

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

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

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

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.

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

> it's massively energy intensive to filter the salt out the newest best ideas still use ~2 KWh/m3 of water

Am I alone in thinking that doesn't sound like a lot? That would be something on the order of 10% of what major cities charge for tap water?

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

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.

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.

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

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

Quite interesting.

This is also why every video needs a transcript: that took me 6min to read, about 1/4 of the video's running time.

The graphical aids in practical engineering videos are quite well done, especially when he creates scale models in the garage. You are missing out if you only read it, if you can afford to spend the time watching.

Nothing prevents inserting video clips — or, for that matter, interactive demos or other media — into the flow of a blog post. Youtube incentivizes its "creators" to optimize for view time, so even the most respected channels can be quite redundant in their presentation. And even when it's well edited and "organized", it doesn't necessarily prioritize what would be most useful.

Is it really considered the Cascades all the way down near LA? I thought the mountains down there were the Sierra Nevada? Did Grady just get that detail wrong, or am I wrong in thinking that the Cascades stops in Northern California?

A cascade is a steep, small waterfall or a series of such falls, often describing anything falling in stages.

Reminds me of when I was talking to friends about the film Chinatown and I referred to it as a movie about the California water war and someone else said “dude, that’s not what that film is about”.

We were both correct.

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.

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.

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

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?

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

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

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

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

Pretty upsetting history along with the interesting engineering.

The California aquaduct system is an engineering marvel.

Insane waterslide

Really enjoyed watching that. Good luck with water LA.

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