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The Los Angeles Aqueduct Is Wild

practical.engineering

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Re: The Los Angeles Aqueduct Is Wild

#81

Post by rtkwe »

smm11 wrote: post #39
rtkwe wrote: post #14

Earlier quoted context omitted.

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.

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/...

Re: The Los Angeles Aqueduct Is Wild

#82

Post by rabid_0wl »

kibwen wrote: post #50
rabid_0wl wrote: post #29

Earlier quoted context omitted.

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

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.

Re: The Los Angeles Aqueduct Is Wild

#83

Post by nostrademons »

mutagen wrote: post #79
kenhwang wrote: post #57

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.

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.

Re: The Los Angeles Aqueduct Is Wild

#84

Post by AnimalMuppet »

schlauerfox wrote: post #76
strongpigeon wrote: post #16

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.

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?

Re: The Los Angeles Aqueduct Is Wild

#85

Post by [deleted] »

jlhawn wrote: post #68
kenhwang wrote: post #57

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.

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…

[deleted]

Re: The Los Angeles Aqueduct Is Wild

#86

Post by kenhwang »

mutagen wrote: post #79
kenhwang wrote: post #57

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.

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.

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.

Re: The Los Angeles Aqueduct Is Wild

#87

Post by bombcar »

rtkwe wrote: post #81
smm11 wrote: post #39

Earlier quoted context omitted.

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.

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 requi…

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).

Re: The Los Angeles Aqueduct Is Wild

#88

Post by bombcar »

kibwen wrote: post #53
bombcar wrote: post #5

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

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 ;)

Re: The Los Angeles Aqueduct Is Wild

#89

Post by tjwebbnorfolk »

gorfian_robot wrote: post #11

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.

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

Re: The Los Angeles Aqueduct Is Wild

#90

Post by vondur »

kenhwang wrote: post #57
jedberg wrote: 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.

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.
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