Is Powell next

Brent

Active Member
#1
I'm getting worried we never learn our lessons and that history repeats itself.

Watching the news of the Oroville Dam's imminent failure reminds me of Glen Canyon Dam in 82/83

Are we next?
 

Dorado

Well-Known Member
#3
We would need another year like this to test that out, since LP is so low to begin with.

But who really knows? But the fixes to the overflow tunnels have never really been put to the test like they were in 82', where the Bu Rec was taken by surprise at the volume of water. In 83' they anticipated a huge runoff and drew the lake down enough that they did not have to use the bypass tunnels nearly as much as in 82'.

You have to have some sympathy for the water managers: if they draw the reservoir's down, and the runoff is not as big as anticipated they get criticized for wasting water. If it comes up more than predicted, or there is a freaky precipitation event(s), and there is not enough capacity for flood control, they are really in for it....
 

Dorado

Well-Known Member
#5
That is a good question. I am pretty sure they had a snow course to measure and predict runoff, but I do not think it was nearly as extensive as it is today. As I remember (from watching the amazing movie about saving Glen Canyon Dam), The real issue was not just the snowpack, which they knew to be huge, but super heavy precipitation later in the season that pushed the runoff over the top....

As a side note, it looks like the total snowpack for all basins above Lake Powell is now almost 100% of the average FOR THE ENTIRE SEASON! And there are still 2 wet months to go...and another storm is coming starting this weekend....
 

Waterbaby

Moderator
Staff member
#6
Apples and Oranges. Oroville is an earthen dam and was built too high for an earthen dam. IT was not engineered, designed or constructed by either the Army Corps of Engineers or the Bureau of Reclamation, built and not maintained by the State of California.
 

Waterbaby

Moderator
Staff member
#7
We would need another year like this to test that out, since LP is so low to begin with.

But who really knows? But the fixes to the overflow tunnels have never really been put to the test like they were in 82', where the Bu Rec was taken by surprise at the volume of water. In 83' they anticipated a huge runoff and drew the lake down enough that they did not have to use the bypass tunnels nearly as much as in 82'.

You have to have some sympathy for the water managers: if they draw the reservoir's down, and the runoff is not as big as anticipated they get criticized for wasting water. If it comes up more than predicted, or there is a freaky precipitation event(s), and there is not enough capacity for flood control, they are really in for it....

They did test it out the next year, which was also a high runoff year, and the method they used to fix the bypass tunnels at Lake Powell performed admirably. Cavitation caused the problem at Lake Powell, the cavitation problem was resolved. The problem at Oroville is totally different.
 

Waterbaby

Moderator
Staff member
#8
That is a good question. I am pretty sure they had a snow course to measure and predict runoff, but I do not think it was nearly as extensive as it is today. As I remember (from watching the amazing movie about saving Glen Canyon Dam), The real issue was not just the snowpack, which they knew to be huge, but super heavy precipitation later in the season that pushed the runoff over the top....

As a side note, it looks like the total snowpack for all basins above Lake Powell is now almost 100% of the average FOR THE ENTIRE SEASON! And there are still 2 wet months to go...and another storm is coming starting this weekend....
I would take multiple high snow years in Colorado to refill Lake Powell and Lake Mead. in 82/83 it was an average snow year and the BOR was caught off guard wth a suddenly wet Spring and had not let Lake Powell down to a lower level to be able to collect so much runoff.

Also of note is the State of California [who is the sole responsibility for Oroville Dam] was informed in 2005 this dam was in need of some major work because the earthen sides presented a big danger in a wet year [like this year]. It was ignored then and has continued to be ignored.
 
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#9
Also worth noting, Lake Powell holds over 7 times as much water as Oroville. So even if we had some crazy extreme precipitation like California has had this year, it would take several years for it to fill up Lake Powell. And even then, the agreements to equalize both Powell and Mead would cause much of that to be released down stream. I'm not putting much hope in Lake Powell getting to full pool again unless we see a change in the weather patterns where we have multiple consecutive wet years.
 
#11
Unregulated inflow in one of those years was 24MAF, enough to fill the lake from empty...
But not enough to fill both Powell and Mead. It's going to take a lot more than that to fill both, which is what it's going to take for Powell to get to full pool. There is no way Powell can get to full pool with a ridiculously low Mead.
 
#12
True, but even after required downstream releases, that year would have added about 16MAF of stored water into the Powell/Mead system. One year like that would have a huge impact on total storage.
 

Waterbaby

Moderator
Staff member
#13
True, but even after required downstream releases, that year would have added about 16MAF of stored water into the Powell/Mead system. One year like that would have a huge impact on total storage.

The two lakes combined is 56 MAF. The trouble with 82/83 was Powell was in good shape water-wise, no one had any idea we were in for an unusually wet Spring that year with a normal snowpack.. BOR had leveled the lake based on the snowpack...... and Mead was in good shape at the time.... both lakes were letting water out like crazy to make room for what happened. Parker, AZ was flooded due to all the dams working full-bore to empty all the lakes to make room, but it was nothing like what they were predicting if they could not solve the problems with the bypass at Powell. No social media then we had to wait for the hourly news updates on what was happening and if the dams were going to hold. Weather always throws a wrench in best laid plans. Right now I just wish we had all that water being sent to sea from Oroville and now Shasta lakes. Tahoe is full and overly full, and according to the news Folsom lake has gone from 25% in December to gaining 230,000 cubic feet in a matter of two days on February 9th and 10th and now letting out 70,000 cfs to make room for more inflow......... with 114,000 coming into the lake each day. If only we could catch some of this on our end.
 

botnb

Well-Known Member
#15
In my mind, there is a difference in the mind of Mother Nature and the minds of our political representatives. Ma Nature is like a wild, untamed, not reasonable force and our pols are wild,untamed, and ..... wait, they are almost the same.. never mind.......:rolleyes:
 

Attachments

#17
We would need another year like this to test that out, since LP is so low to begin with.

But who really knows? But the fixes to the overflow tunnels have never really been put to the test like they were in 82', where the Bu Rec was taken by surprise at the volume of water. In 83' they anticipated a huge runoff and drew the lake down enough that they did not have to use the bypass tunnels nearly as much as in 82'.

You have to have some sympathy for the water managers: if they draw the reservoir's down, and the runoff is not as big as anticipated they get criticized for wasting water. If it comes up more than predicted, or there is a freaky precipitation event(s), and there is not enough capacity for flood control, they are really in for it....
 
#18
http://snowpack.water-data.com/uppercolorado/index.php

We are having a great water year SO FAR. We are even ahead of snowpack for 2011. But it's only February. If we have an average spring, runoff will be big. If we have a wet spring, we will have HUGE runoff. (look at 2011... winter was above normal, but SPRING was HUGE!!) But currently the lake is 110 feet below full pool, so even a VERY WET spring would not FILL Powell. Plus, if the VERY WET scenario happens, they could increase releases to Mead to compensate. Say w get a 60 or 70 foot runoff (unprecedented?), and the lake peaks at 3650 in July 2017; remember, just from routine releases, the lake will drop back to 3620 by April 2018. So, it would take 2 or 3 or 4 more years like this one to even get close to full pool. Because the more water that comes in, the more they will let OUT. So, yeah. I think they have learned their lesson. If the lake was over 3650 right now, they would be prepared to open the floodgates come April to avoid coming close to full pool. With Lake Mead very low, there is lots of room downstream!

In short, Colorado is not the Sierra Nevada, and Lake Oroville is not Lake Powell. Don't worry, celebrate!
 

Dorado

Well-Known Member
#19
Very unlikely we will get anywhere near filling LP. But we are WAY ahead of the snowpack in 2011. And the forecast for the next few weeks is cool and wet.

The graph showing percent of average is deceiving. Having 150% of average at the beginning of March is much more impressive than having 200% at the end of May (like 2011), when much of the snowpack has already melted. We currently have 106% of average snowpack for the entire water year, with 6 more weeks of typically wet late winter/early spring to go. And the lowland snow, which is not accounted for in the SNOTEL sites, is 200-400% of average already. This water year may not break any records, but it is undoubtedly going to be in the top 5 since records have been kept when all is said and done. I will be very surprised if we do not get substantially more runoff than 2011!
 
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