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Comment by jeffbee | Hacker News Reader

Our reservoirs are empty. Why would another reservoir help up?

The fact is that California's urban water use has been declining since 1976, in absolute terms, not just in per-capita terms. The East Bay Municipal Utility District, for example, now only delivers half the water it delivered in 1976, despite the fact that the population in its service area has increased by 50% over that period. Conservation and efficiency are outpacing population growth. EBMUD now owns double the reservoir capacity it actually needs.

People who advocate for new reservoirs in California, especially people who advocate for it in East Coast editorial magazines, are representing the interests of agriculture megabusinesses who want to rip off the tax payers some more. Don't believe them.

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Your point could be valid. A quick googling of water demand in CA produces the following. Urban water use is only 10% of total water use in California. Agriculture uses anywhere from 30% (wet year) to 70% (dry year). Just raising cattle in the state uses anywhere from 100-250 million gallons per day.

How much does almonds and rice do? And could you grow plants on the cow land?

Makes you wonder wtf is going on there (Almonds/Rice)? Just as insane as irrigating Alfalfa fields to harvest hay for cattle to eat.

> Our reservoirs are empty. Why would another reservoir help up?

I’m not an expert, but presumably the reservoirs are empty because too many people were drawing on them (too much load per unit capacity). Increasing the reservoirs spreads the load across greater capacity.

But in general California (and much of the rest of the country) needs to stop it’s unsustainable agriculture practices.

The problem is that California is the breadbasket for a ton of US goods. You're right, we need to stop but it's gonna be painful for a lot of industries.

What are the major agricultural commodities for which California is the breadbasket, and how many of those commodities could be sustainably grown elsewhere in the US and/or imported from abroad? Besides maybe almonds (which can presumably be easily imported), nothing springs to mind as predominately californian.

California totally dominates the fruit market. Georgia might call itself the Peach State but California produces 20 times more peaches. California produces 90% of the nation's grapes and twenty times more wine than the second-place state. It's not necessarily that you couldn't grow these elsewhere, but it is a path-dependent process by which government subsidies have pushed all this production to California and killed the industries elsewhere. Changing this so fruits and vegetables are widely produced in every state would involve an abrupt discontinuity that entrenched California growers are sure to oppose.

As long as the other states’ diet can be 100% corn based, they’ll be fine.

Interesting. This seems believable. Supply chains don’t turn on a dime and unsustainable farmers will always support the unsustainable practices on which they depend, but we should start making moves in the right direction now.

> Changing this so fruits and vegetables are widely produced in every state

This isn’t the requirement. The requirement is that we source sustainably grown food. That can come from Mexico or the lusher regions of the US or wherever. I don’t think we need to grow oranges and lemons in Alaska or corn in Hawaii, we just need to be able to get sustainably-grown food to those places.

Explained it better than I could!

"Our reservoirs are empty. Why would another reservoir help up?"

A serious question? More water in reserve = more water in reserve.

If you fill 4 glasses with water now, and then then EBMUD turns the water off for the rest of the day due to a broken main (I know EBMUD really well), you'll have 4 more glasses of water to drink than you would have, otherwise. Simple math, really.

OP's point is that you have two glasses now, which are empty. Another two to make four and you'll have four empty glasses.

You need to address the reason why they're empty. You said you know the system well, so do you mind explaining?

They’re empty now, but presumably they would not have been pre-drought, delaying the point when the current shortage begins.

You can't presume that. You have to show it. In particular, you have to show the new reservoir would capture water that would last long enough to matter.

It has been years since some of the large reservoirs were close to full. Where specifically do you believe new reservoirs should be built? And why do you do believe that they will capture water that keep from evaporating long enough to make a difference during the next drought cycle?

I don’t think it is a given that, this time, there will be a post-drought that fills the current reservoirs. If so, if extra reservoirs were built years ago, they would have been useful exactly once.

On top of that, that ‘useful’ could have been very limited. For example, shortening a half year drought by a week would not be worth anything if it just meant crops would die a week later.

You have to do some serious modeling on expected rainfall, the costs of reservoirs and water usage to figure out whether additional reservoirs are worth the investment.

So 100% of reservoir loss is due to evaporation? In the analogy, filling the glasses before EBMUD turns the water off is like filling a reservoir during (even brief) rainy seasons.

Think you would a better leg to stand on if California’s reservoirs actually filled up during the year.

As it stands California’s reservoirs never seem to fill completely anymore. Adding more reservoirs won’t help store extra water if it simply isn’t falling from the sky.

The Oroville dam was so full it was at risk of overtopping just a few years ago.

https://en.m.wikipedia.org/wiki/Oroville_Dam

More reservoirs doesn't make more water in the first place. This is about how much that falls from the sky in the first place.

You should not stop all the water from reaching the ocean in the first place, bad things happen when you do that. We are reaching the point where we just have enough water to keep the rivers flowing so we don't kill all the wildlife that exists in them, we're not adding significant amounts of water to storage.

If you distributed the total available water to more reservoirs then the loss rate from evaporation would actually go up due to an increased ratio of surface area to volume. Simple math, really.

Building more reservoirs doesn't mean there's more water in reserve, it just means there's more space to store water.

The water cycle covers the entire state so as long as you don't set up in a desert or a hundred miles from the nearest waterway, chances are the reservoir can be filled up on a regular basis.

We're storing a teeny tiny fraction of all the water that goes through the system.

2 things.

One is you want to keep the rivers flowing in the first place. If you impound too much water, you don't have rivers, you have dry creeks and all the wildlife in them dies.

The big one is water rights. The water is not the states to impound in the first place in many cases. If I have particular water rights, and you block them, I can sue you out of existence under existing laws, laws that are going to be very hard to break with our current legal system.

> One is you want to keep the rivers flowing in the first place. If you impound too much water, you don't have rivers, you have dry creeks and all the wildlife in them dies.

That's only if we build massive dammed reservoirs that try to serve dense populations from a single source like Hetch Hetchy supplying the Bay Area. A system of smaller reservoirs dotted across the state would serve the same function without the concentrated ecological impact. San Francisco has three terminal reservoirs within its city limits, for example.

> The big one is water rights. The water is not the states to impound in the first place in many cases. If I have particular water rights, and you block them, I can sue you out of existence under existing laws, laws that are going to be very hard to break with our current legal system.

That's why utilizing the whole water cycle is important, rather than concentrated sources like rivers and streams. A farmer can prove you're taking his inch of water by comparing upstream of the installation but it's much harder to do that if snowmelt is being collected in hundreds of smaller reservoirs along the mountains. (IANAL, so grain of salt and all that)

There are already 1500 reservoirs in California. It's a myth that there are un-impounded streams waiting to be captured. There really are not. Just look at the area around Placerville. There is Sugar Pine, Loon, Big, French Meadows, Ice House, Hell Hole, Stumpy Meadows, Union Valley, Sly Park, and, of course, Folsom Lake. That's all in a diameter of only 30 miles.

Generally that snowmelt either goes into existing streams or penetrates into groundwater though. It's not workable to just capture every drop of snow even if we could from and engineering and water rights standpoint, that water is already feeding environments that would dry out and pose more fire risk without that water.

It only seems simple if you're the kind of imbecile they put on the staff at the National Review. California has several reservoirs that aren't fed by gravity runoff, but by pumping ("off stream" reservoirs). All of the newly proposed reservoirs are of this type, such as the Sites Reservoir. To fill these you need excess water elsewhere. We don't have excess water elsewhere, thus we could not fill them. This isn't a simple matter of time-shifting water from one year to the next because as the OP is pointing out this is a long-term phenomenon that is permanently decreasing our steady-state precipitation.

I'm guessing that your comment is being downvoted simply for the first sentence. The rest of your comment is factual.

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