Dam and cap the LA River to turn it into a reservoir (Los Angeles: insurance, house)

[drunk on kool aid]

Because of global warming, less of our water is going to be stored as snowpack and will just flow out to the ocean so we need to capture and store it ourselves.

I had been thinking for a long time about where we could dig massive reservoirs to capture stormwater and city runoff and the answer was already here.

If the final concrete-lined section of the LA River was dammed at the ends, we could capture every drop of runoff, treat it and use it. This, along with total toilet to tap recycling would go a long way toward water security and independence without siphoning it away from hundreds of miles away or energy intensive and environmentally questionable desalination. Perhaps Gov. Brown's water tunnel money can be diverted for this project.

I'm picturing dams at the start of the concrete lined section and one near where it ends in Long Beach. Giant treatment facilities will have to be sited somewhere. Because the stored water might become fetid, the entire section should be capped and turned into a 20 mile long ribbon park that will dwarf NYC's High Line.

It's insane that some folks are talking about tearing out the concrete. I'd even be up for pouring more if it'll help our water problems.

Advantages:
- Animal poop, engine oil and shopping cart contaminated water doesn't drain into the ocean, ruining its quality. Cleaner ocean water means better health for us and sea life.
- We get delicious water to drink or inject to replenish groundwater and stave off saltwater intrusion.
- We get a giant park that's easily accessible to millions.

Disadvantages:
- We lose an iconic symbol of LA that's been immortalized in photos and movies.
- Hipsters don't get to kayak all the way to the ocean

Lately there's been a lot of people who are excited about LA River restoratiion and I'm sure my idea won't sit well with them, but in LA, we do things our own way, and permanently solving our water problem is a huge insurance policy for our future. And if we withdraw our proboscis from northern water supplies, maybe those mean NorCal folks will start to wuv us.

Thoughts?

P.S. All of the soft-bottomed portions of the river should continue remediation.

[BRinSM]

I'd imagine that if the river was a viable water source, it would have been used as such already.

[MordinSolus]

What are the environmental concerns over desalination plants?

[BRinSM]

Originally Posted by MordinSolus

What are the environmental concerns over desalination plants?

there are 3 arguments against desalination from what i've read:

1. it's very expensive
2. the amount of energy required to generate potable water is quite high
3. scientists are unsure of the effects of increased salt concentration on local ocean environments.

I think desalination will be treated much like oil extraction from shale. when the cost of water to the end user is expensive enough to justify the added cost to the treatment process, we'll see a proliferation of desalination plants showing up along the coast.

[MordinSolus]

But don't modern desalination plants use hydropower and collect the extracted salt?

[arleigh]

I happen to agree with you OP, Where I lived as a child in Montebello, the river bed rarely was full and making it a reservoir would be a boon to the economy , even adding fish and inspire that industry would be a big game changer economically.

If damming were engineered so that during the wetter months, the were relieved for anticipated rain fall flooding would be avoided for which they are designed. the could be made even deeper for that matter ,to insure the maintenance of some water level. There are already ports for sharing the load between them ,we use to play in them. I remember 4 separate canals .
Of course what makes sense, and what get's done, are two very different things.

[BayAreaHillbilly]

The most prolific tributary streams of the LA River are already dammed. Although you indirectly have raised a good point. Peak run off of CA rivers often does go out to sea. The easiest way to recover it is to divert it to perc ponds. But if any pumping is needed the cost starts to look unattractive. The next best thing to perc ponds would be low elevation storage but where to get all that land?

[drunk on kool aid]

Originally Posted by BRinSM

there are 3 arguments against desalination from what i've read:

1. it's very expensive
2. the amount of energy required to generate potable water is quite high
3. scientists are unsure of the effects of increased salt concentration on local ocean environments.

I think desalination will be treated much like oil extraction from shale. when the cost of water to the end user is expensive enough to justify the added cost to the treatment process, we'll see a proliferation of desalination plants showing up along the coast.

Originally Posted by MordinSolus

But don't modern desalination plants use hydropower and collect the extracted salt?

I initially thought that desal ends up with pure water and a pile of table salt but that's not true. You actually end up with pure water and a huge amount of super-salty water that has to be disposed of. To add to what BRinSM said, there are concerns about where you dump the super-salty water. Usually it's piped offshore but making the local waters saltier has environmental issues. Then there's also the question of what gets sucked into the intakes.

Like money, electricity is fungible so there's no guarantee that a desal plant uses only hydropower (which we don't have much of anyway - if we did, that would mean we have a lot of water, making desal unnecessary).

Originally Posted by Harrier2

Naw - the LA River is already becoming a destination with a few stretches being declared navigable waterways.

Imagine that - L.A. will soon be known for its awesome river and not just beaches!

Lets allow the river to be its wild self rather than further encasing it in more concrete.

Instead, we'll be known for a massive ribbon park over the concreted sections of the river. A unique destination. A small creek can be built into it to maintain its river-ness.

Originally Posted by BayAreaHillbilly

The most prolific tributary streams of the LA River are already dammed. Although you indirectly have raised a good point. Peak run off of CA rivers often does go out to sea. The easiest way to recover it is to divert it to perc ponds. But if any pumping is needed the cost starts to look unattractive. The next best thing to perc ponds would be low elevation storage but where to get all that land?

The practicality of the idea is that the LA River is already a concrete lined reservoir - it just needs its ends sealed so the water isn't lost. You don't have to look for new land or spend gazillions to build one from scratch.

Plus if we cap it (for sanitary reasons and to eliminate evaporation) we can get a signature park out of it.

*************************

We don't get a steady paycheck of water; it's feast or famine. During our increasingly rare winter storms there is an immense amount of storm runoff that should be collected.

I'm also worried about all the surface pollutants being washed into the ocean. At some point we will have to clean it before it contaminates our beaches. Pristine beaches boost human enjoyment and potential for tourism dollars (watersports, fishing, diving, etc).

Desalination doesn't address runoff pollution and may add to environmental headaches.

Aside from evaporation and ground absorption, we lose water primarily through storm drains and sewers. All of that water needs to be recycled.

We're at a crossroads about what to do with the LA River. There's a huge amount of emotional momentum to restore it to its natural state but if we factor in our water future, I think a different path is best.

What better ideas do people have for our water security and reducing runoff pollution?

[saybanana]

Dams and caps are on the extreme side of saving water and also very expensive. I thought about the idea of cisterns (underground reservoirs) after seeing a something on the Discovery Channel about Tokyo's cisterns. Reminds me of that huge Moria hall in Lord of the Rings. It would be great to have a series of cisterns along all SoCal rivers to store rain water or water treatment plant discharge and are also a back up to dams in case of a severe 100 year flood. I think the picture plans for the LA River restoration puts some small dams or weirs along sections of the river. It's not high, but enough to create a fuller looking river enough to kayak through. There are other large rivers in the SoCal area like Ventura's Santa Clara River, LA's San Gabriel and LA Rivers, and the long Santa Ana river that goes from San Bern to Orange County and maybe some smaller ones.

It would be easier and cheaper to do water conservation efforts for all of SoCal like plants drought tolerant and native plants. Low flow toilets and those new urinals you see in many buildings these days which dont need constant flushing. Catch water while waiting for shower to warm. Use grey water. Other conservation efforts. Not sure why the Coachella Valley and the areas there have dozens of green golf courses. Seems like a terrible water wasting place to put them where temps are in the 100s for many months.

I watched several episodes of House Hunters International in Australia where many homes have these large water tanks that collect rooftop rain water. If every building had that here, we can use that to water the plants. There are some people that do that already but it's a very small percentage.

[Lovehound]

Just wondering, has anybody who is reading this topic or lives in Los Angeles or at least the San Fernando Valley ever heard of the Sepulveda Basin?

There we collect drain water and treat it and use it to fill ... guess what? ... an artificial lake! Lake Balboa!

The reason the L.A. River and all the rest is not recoverable is because they are also our flood channels, and every time it rains (infrequently) all the oils are washed off the streets and into the storm drains and come out (in the Valley) at the Sepulveda Basin.

The real problem is that the water is toxic. You'd be better off pumping water out of the ocean and taking the salt out.