Live data from Hacker News

The Los Angeles Aqueduct Is Wild

practical.engineering

101–110 of 216 posts

Re: The Los Angeles Aqueduct Is Wild

#101

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.

[deleted]

Re: The Los Angeles Aqueduct Is Wild

#103
post #14

Earlier quoted context omitted.

> 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.

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

Re: The Los Angeles Aqueduct Is Wild

#104
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

Re: The Los Angeles Aqueduct Is Wild

#105
post #45

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 (b…

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.

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

Re: The Los Angeles Aqueduct Is Wild

#106
post #74
post #28

Earlier quoted context omitted.

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!

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 h…

> 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.

Re: The Los Angeles Aqueduct Is Wild

#107
post #45

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 (b…

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.

Re: The Los Angeles Aqueduct Is Wild

#108
post #104

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...

Re: The Los Angeles Aqueduct Is Wild

#109
post #90

Earlier quoted context omitted.

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.

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.

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

Re: The Los Angeles Aqueduct Is Wild

#110
post #37

Earlier quoted context omitted.

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, a…

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

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

Post reply on HN