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"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 wit

"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.

aesh2Xa1 5y ago
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?
- lovecg 5y ago
  They’re empty now, but presumably they would not have been pre-drought, delaying the point when the current shortage begins.
  - wpietri 5y ago
    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?
  - Someone 5y ago
    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.
- eplanit 5y ago
  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.
  - avianlyric 5y ago
    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.
    - jdavis703 5y ago
      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 https://en.m.wikipedia.org/wiki/Oroville_Dam
  - pixl97 5y ago
    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.
  - defterGoose 5y ago
    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.
TchoBeer 5y ago
Building more reservoirs doesn't mean there's more water in reserve, it just means there's more space to store water.
- akiselev 5y ago
  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.
  - pixl97 5y ago
    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.
    - akiselev 5y ago
      > 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)
jeffbee 5y ago
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.
- JKCalhoun 5y ago
  I'm guessing that your comment is being downvoted simply for the first sentence. The rest of your comment is factual.

aesh2Xa1 5y ago

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?

lovecg 5y ago
They’re empty now, but presumably they would not have been pre-drought, delaying the point when the current shortage begins.
- wpietri 5y ago
  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?
- Someone 5y ago
  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.
eplanit 5y ago
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.
- avianlyric 5y ago
  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.
  - jdavis703 5y ago
    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 https://en.m.wikipedia.org/wiki/Oroville_Dam
- pixl97 5y ago
  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.
- defterGoose 5y ago
  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.

TchoBeer 5y ago

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

akiselev 5y ago
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.
- pixl97 5y ago
  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.
  - akiselev 5y ago
    > 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)

jeffbee 5y ago

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.

JKCalhoun 5y ago
I'm guessing that your comment is being downvoted simply for the first sentence. The rest of your comment is factual.