Water level analysis 1998-2018 just because I’m curious…..

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Pegasus

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I thought I’d share this as you all might find this informative reading while perusing WW when you are on a conference call at work.....

I looked up Lake Powell water levels in the database for July 1st of each year 1998-2018. I used this date as it’s generally after most of the runoff is completed and before the larger net outflows begin.

Over the 5-year timeframe from 7/1/99 through 7/1/04, the lake dropped 111 feet, which is over 55% of total lake capacity – 3696 as of 7/1/99, 3585 as of 7/1/04.

After that horrible 5-year period, over the next 14-years starting 7/1/05, the lake level has generally stayed close to the same level (with obvious annual changes, but as a percentage, not near the size of changes as in the awful 99-04 years). 7/1/05 level was 3607 and 7/1/18 level was 3610 – only 3 feet difference.

My learning: I didn’t know that Lake Powell lost over half of its total water capacity over the initial 5-year start of the drought from 1999-2004. And I didn’t know that from 2004 until now, the overall net inflow/outflow is zero as of 12/4/18. The 7/1/04 lake level was the same as the 12/4/18 lake level – 3586.
 
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Love stuff like this, have wasted a many hours doing similiar studying. I wonder if this would mean that we need about five straight above average years of runoff to get back to those upper averages?
 
Great information.

With some conservation, maybe 3 average to above average water years can fill the lakes. (Powell and Mead).

I don't think we've had 2 straight years of good snow pack for some time now. It would be nice to string several good years together instead of one up and one down.

Hoping for the best.
 
I think to get a more accurate analysis you would have to use the same dates for lake mead and compare the data. I think the water level drop from 05-18 there will be more drastic.
 
I think to get a more accurate analysis you would have to use the same dates for lake mead and compare the data. I think the water level drop from 05-18 there will be more drastic.
You lost me! You are saying to provide a more accurate analysis of LAKE POWELL's water level (implying the database is not accurate?), I need to look at the LAKE MEAD water levels? I wasn't trying to compute inflows and outflows for the Colorado river basin; I was comparing water levels for Lake Powell and Lake Powell only.

Is your point that if I was trying to compute the overall gross and net Colorado River basin inflows and outflows, I should look at Lake Mead also? If that is the proposition, might as well include Flaming George, Lake Havasu, etc from top to bottom and I agree that would show data for the entire Colorado river basin. That would be interesting to see and I'm curious what that analysis would show - a decrease from 05-18 I suspect, but that is not what I was providing an analysis of. Apples and oranges.
 
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I take a bit of comfort in this brief analysis, and I am hoping that this is a logical, smart response. Anyway, thanks for a succinct summary. It sure is a fascinating thing to ponder. Meanwhile, let's hope for a couple of solid winter back to backers.
 
You lost me! You are saying to provide a more accurate analysis of LAKE POWELL's water level (implying the database is not accurate?), I need to look at the LAKE MEAD water levels? I wasn't trying to compute inflows and outflows for the Colorado river basin; I was comparing water levels for Lake Powell and Lake Powell only.

Is your point that if I was trying to compute the overall gross and net Colorado River basin inflows and outflows, I should look at Lake Mead also? If that is the proposition, might as well include Flaming George, Lake Havasu, etc from top to bottom and I agree that would show data for the entire Colorado river basin. That would be interesting to see and I'm curious what that analysis would show - a decrease from 05-18 I suspect, but that is not what I was providing an analysis of. Apples and oranges.

I think what he is getting at, is that Lake Powell will never completely fill until Lake Mead approaches capacity as well. The two are closely tied together. The real deficit of water through the system is Powell and Mead together. The other reservoirs are much smaller, and can fill up more quickly than Powell and Mead.

I have always found it odd how large both Powell and Mead are compared to the size of the Colorado River, which is not that big compared to other rivers with large reservoirs. The Colorado River is the 38th largest river by discharge in the US!!!
 
83 - 84... that was nuts. I remember gawking at the wooden dams built on the spillways to prevent damage to the tunnels. Piute Farms Marina became a "bucket list" destination for us (just to say we had been there). At that time I never expected that there would be concerns about the lake drying up. We even celebrated that the lake had finally reached full pool and expected it would stay that way.

I have not been back since before the 00's drought, but my Dad went back last summer. He said the lake is unrecognizable compared to the mid 80's.
Not sure what my point is except that climate can be fickle. Ten years from now we might be dealing with another 00's type drought or another series early 80's series of wet winters and springs. In one scenario the lake becomes a sand pit, in the other we worry about integrity of the Colorado dams. The best we can do is to be ready for either scenario.
 
Interesting thread... and I was also curious about looking at Powell and Mead in tandem over the years, since they are really linked. And one day a couple of months ago, I did just that--compiled Mead and Powell data back to 1963 for Powell, and 1935 for Mead...lake levels, storage volume, etc. Mostly was curious to see what the percentage of capacity they were at individually and collectively since Powell came on line. Here's what you find since Powell hit full capacity in 1980:

1) Both reservoirs were essentially full in 1980 (actually 90% capacity if you took the yearly average, which is what I did);
2) Both stayed essentially full (or close to it) through 1988;
3) Powell dropped to 58% full by 1992, while Mead stayed in the 75% range--the effort was made to keep Mead full... collective storage was 67% that year;
4) Both reservoirs hovered in the 80-90% range through the rest of the 1990s, until hitting essentially full capacity again in 1999;
5) Sustained drought from 2000-05 dropped storage in Powell to 41% in 2004, and in Mead to 56%, collectively 49% of full capacity--lowest since 1969;
6) Collective storage from 2005-12 stayed at or just above 50% of full capacity, with Powell rising slowly while Mead dropped slowly in that time;
7) Collective storage from 2013-18 has dropped to below 50%, bottoming out in 2016 at 43% (currently at 46%), lowest since 1968;
8) From 2013-18, Powell has hovered around 50% of capacity while Mead has bottomed out and maintained an all-time low of 39% since 2015 (lowest previous to current period was 46% in 1955, excluding the first few years of filling Mead--but even in 1940 it was at 80%, just 5 years into operations)

So the fact is that the collective storage is lower than ever since the time Powell was just filling up, and Mead is in critical shape. So even in a super wet and snowy year (hope we maintain that), first priority in water management terms will be to get water to Mead... so Powell will not likely see a significant rise this year... seems doubtful it will get back to 3600 anytime soon, as long as Mead remains in critical condition...
 
Wanted to get in before the lock... First, Havasu is not allowed to get lower than I believe 445 feet due to water intake pipelines for the city. If the water level is higher than 450 feet, then there are issues with the Parker Dam and boat docks. So would never expect that lake to vary more than 5 feet ever. Has nothing to do with CA water. As for CA water, voters did pass Measure W back in November 2018 with 1.8 Million Yes votes vs. 0.8 Million No votes. Measure W is a property tax per impermeable square foot ( the more house you own, the more tax you will pay ) in Los Angeles County. The money is to be used to capture rain and stormwater, with the goal to wane Los Angeles (as much as 30%) off of outside water sources. And I did vote yes knowing my property tax would increase $65. But back to Powell, and not downstream... What I'm not understanding is that we are having a normal snow accumulation in CO, (and normal rainfall and snow so far in CA, oops sorry), but the Jan USBR report is saying only 7 m.a.f. inflow (64% of average), and at best expect peaking out at 3600 ft mid July 2019. And then in 2020, they suggest the median being higher than in the coming year. I'm sure there are valid reasons, but my quick read is they appear to be pessimistic for 2019, and then again optimistic for 2020.
 
...that's a good question, about why the USBR's relative optimism for 2020. My only guess is that this year the releases from Powell are projected to be above the minimum 8.23 MAF release (USBR projects a likely 8.62 MAF in 2019) to meet legal requirements in the lower basin, and perhaps they are being optimistic that it will return to closer to 8.23 MAF in 2020? Hard to know from the reports...
 
...and just to expand on all this...

On January 23, Lake Powell fell to 3577, or about 123 feet below full. This is the lowest it's been on this date since 2005, when it was at 3563. That year, the lake ultimately bottomed out at 3555 in April 2005, the lowest it had been since 1970.

There is a wide degree of possible variation in USBR’s January 2019 report, but the most probable projection for 2019 is that the lake will hit a minimum of about 3565 in April, and rebound to about only about 3580 in June before declining again to about 3565 by the end of the year. If this projection holds, this shapes up to be the lowest the lake has been since 2004-05. Of course, all this changes with a big snowfall pack in the Colorado River watershed, but still too early to tell how this plays out.

As a practical matter, the Castle Rock Cut is only usable as long as the lake remains above 3580 or so, thus not usable as of January 8 (when the lake fell to 3579). And based on the projections of the Bureau of Rec, it will likely remain unusable for all of 2019. Of course, a big snowmelt in the spring could change that, but right now that's not certain, and the Bureau will continue to focus on releasing sufficient water to Lake Mead to make sure it remains viable as a water supply for the Lower Basin states (CA, AZ, NV), which is a legal requirement under the Colorado River Compact as amended in 1928, 1941 and 1944.

The “elephant in the room” is that although the Upper Basin states (CO, UT, NM, WY) have rights to half of the water in the basin (less a small portion for Mexico), none of these states actually use any of the water in Lake Powell. The only current direct use of any of Powell's water is by the city of Page and the nearby Navajo Power Plant. That's it. So the water managers use Powell (and reservoirs above Powell) as a giant storage bin "just in case" these states ever want to exert their water rights, but in the meantime, the three downstream states fully use their legal water allocations. (By the way, 85% of California’s allocation is used to irrigate things like lettuce and alfalfa in the Imperial Valley—very little is actually used for municipal use, most of which comes from groundwater or the Sierra Nevada.) Hence, the ongoing need to send water to Lake Mead.

The unspoken part of this is: what happens to Lake Powell (or really the whole Colorado River system) when UT, CO, WY, or NM exert their latent unused water rights? That’s when the fight really begins…

In the meantime, I’m glad to enjoy Lake Powell while it’s here…
 
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Get ready with the growth on the front range, the municipalities are scrambling to find water. The city of Denver has a feeder lake call williams fork that runs into the Colorado river. Last time I was there, I talked to a couple of Denver water employees who said that the city is looking at redirecting or trading water rights with some of the other state agencies. It is just a matter of time before the upper Colorado states start tapping into the water supply. All of the front range is scrambling for water, due to the unprotected growth there.
 
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