Returning to Elevation 3588 in Lake Powell – Can It be Done?

JFRCalifornia

Escalante-Class Member
Since the beginning of 2020, Lake Powell, like the sun in the late afternoon, sometimes appears to be slowly sinking over the horizon. With all the recent reports of impending doom from continued drought, and just seeing things with your own eyes, it’s easy to believe this trend will go on forever until nothing of the lake is left at all. And yet, it’s just as easy to forget that 2019 was a banner year for Lake Powell, one in which it rose 53 feet that spring. That wasn’t so long ago, but right now it sometimes feels like an eternity.

Rather than focus on the extremes to predict a future outcome, its sometimes helpful to focus on the average. The mundane. The ordinary year. And with that concept in mind, I wanted to figure out the answer to this question: What would it take to make Lake Powell rise again, and then stay there? To make the marinas, launch ramps, the Castle Rock Cut—all of the key recreational infrastructure—usable and viable for the long haul? And practically speaking, that means this: what would it take to keep the lake over elevation 3588? That’s the target elevation identified by Fill Lake Powell that would achieve those goals.

Figuring that out is a tall order, and depends on many factors, some of which can’t be controlled (like the snowpack), but some of which can (like water use). And of course to really solve that puzzle, you’ve got to consider the entire system—not just Lake Powell, but Lake Mead too. And the other smaller reservoirs. Not just water use in the Upper Basin, but all seven states and Mexico too. It’s complicated. But as with any complicated puzzle, it’s best to take it one piece at a time, and eventually you will fill in the blanks. Complete the picture. Solve the problem. Or at least identify what it would take to solve the problem. And from there, you can change the way things have always been done into the way they need to be done.

All that means, for our purposes, starting by focusing on Lake Powell. I’ll save Lake Mead and the Lower Basin for another day.

Where to begin? For all the numbers that can be run, the “what-if” scenarios that can be considered, it’s best just to simplify that challenge.

It’s basically just a simple question of inflow vs. outflow.

Let’s first consider outflow. For Lake Powell, there’s really three important factors to consider, but here’s the only one that really matters: USBR’s releases through Glen Canyon Dam. Sure, there is also a small amount directly used from Lake Powell by the city of Page, and then there are evaporative losses from the lake, but both are orders of magnitude less than what flows through the dam. And then, yes, there is the theoretical drain from future water diversion projects not yet online, and perhaps never will be, such as the proposed pipeline to St. George.

With the exception of evaporative loss, all those are controllable factors.

And then on the inflow side, snowpack (precipitation in general) is by far the most important issue, but unlike outflow through the dam, this is out of anyone’s control. There are also other important considerations: the amount of water diverted to serve the needs of the Upper Basin states, and the amount of water available for release stored in the reservoirs above Lake Powell. Unlike the snowfall, these are controllable factors.

In May 2022 the USBR issued its latest 24-Month Study, which forecasts inflows and outflows for all reservoirs affecting the entire Colorado River watershed. The forecast is based in part on projected long-range precipitation forecasts, historic trends, and projected releases from each reservoir. The forecast extends through May 2024, or roughly midway through Water Year 2024 (WY 2024).

Based on this, and other existing USBR documentation, I developed sixteen scenarios to model what could happen to Lake Powell depending on the various factors described above related to inflow and outflow. The most important of these factors is how much total water would be available in the system before anybody uses or stores it. In a simplified model, this number is possible to reverse engineer from existing reported data:

Total Water Availability = Inflow to Lake Powell + Upper Basin Water Use + Upper Basin Additional Storage + Upper Basin Reservoir Evaporation

My report goes into some detail about what those mean and the assumptions behind them, but I'll leave that to those interested in reading the full report.

And then there’s the question: what should be considered a baseline “average” year for modeling purposes? Is it the historic average inflow since Lake Powell came into existence? That seems too broad. Or maybe the period USBR focuses on to establish an “average” inflow, which is 1991-2020? Or should it be something more recent, reflecting the observed realities closer to our time? For example, the 5-year period 2016-20 was a very “average” time in the life of the lake. In terms of inflow, it featured two good years (2017 and 2019), two bad years (2018 and 2020), a pretty average year (2016). In all, the average inflow to Lake Powell during that time was about 8.99 maf, which is a little less than the USBR’s reported 1991-2020 average of 9.6 maf. Based on that, it’s reasonable to use the 2016-20 period as a more conservative “baseline average”, because it would tend to produce less optimistic results when projecting percentage increases (or decreases) from that baseline. It’s also a period where we have very detailed and realistic recent water use data for both the Upper and Lower Basins. For all these reasons, the period 2016-20 is what is used as the baseline “normal” for the purposes of this study.

Based on the assumptions described below, the Total Water Availability in the Upper Basin on average from 2016-20 was 13.6 maf.

What went into developing the various modeled scenarios? Were they just arbitrary? Spitting into the wind?

Sixteen scenarios were developed to predict what would happen to Lake Powell’s surface elevation through Water Year 2027 (WY 2027). Each of these varied one or more of the factors discussed above. In general, these scenarios considered a range of future Total Water Availability via snowpack, from 40% less than the 2016-20 average, to 20% more than average (something like what happened from 1996-2000). Within many of those scenarios, consideration was given to reducing existing Upper Basin Water Use anywhere from 5% to 50% in order to test the sensitivity of that variable and its effect on creating more downstream inflow potential to Lake Powell. Or increasing (or decreasing) flows from the upper reservoirs such as Flaming Gorge. Or varying the outflow through Glen Canyon Dam, although in general, I tried to adhere to existing USBR protocols for that. No effort was made to address Lower Basin water use or effects on Lake Mead in general. While those are extremely important considerations in the big picture, I left them for another time. But they are important.

And without getting into how the sausage was made, I'll cut to the key conclusions of the study, some obvious, some less so:

1. The most important factor in maintaining Lake Powell’s volume is total water availability, primarily through snowpack in the Upper Basin.

2. If the next 5-year period (WY 2023-27) matches the total water availability that occurred from 2016-20 (a very modest goal in historic terms), it is possible to achieve the target elevation of 3588 during WY 2025, although it would require a 5% reduction in Upper Basin water use during that time.

3. It is possible to achieve the target elevation of 3588 in WY 2025 even with a 5-year period with 5% less available water than in 2016-20. But it would require a 5-10% decrease in Upper Basin water use, and potentially additional releases from Flaming Gorge and other Upper Basin reservoirs that could further reduce capacity in those lakes.

4. In any scenario, reducing Upper Basin water use by 10% could add 400,000 AF to Lake Powell each year, which would raise the lake annually 5-6 feet by itself.

5. If the watershed sees a 5-year period of water availability similar to what occurred in 2000-04, which was about 40% less than the 2016-20 average, the outlook is grim. Only substantial reductions in Upper Basin water use and releases from upstream reservoirs (particularly Flaming Gorge) would allow Lake Powell to avoid hitting the dead pool elevation of 3370 in WY 2025. With this sort of 5-year flow regime, it would be impossible to avoid dropping below the minimum power pool of 3490, no matter what was done short of drastically reducing outflows through Glen Canyon Dam to the point of jeopardizing water deliveries to the Lower Basin and power production through Hoover Dam.

6. Conversely, with a 5-year period of water availability 20% above the 2016-20 average (similar to what happened in 1996-2000), it would be possible to fill Lake Powell to 3700 by 2027, provided that outflows through Glen Canyon Dam are generally limited to 8.23-9.00 maf, rather than the larger releases that typically occur in such higher flow years in support of increasing the volume of Lake Mead.

What this all says is that the watershed is a highly dynamic system, and very sensitive to what happens in any five-year period. Long-range precipitation forecasts in the southwest are generally not optimistic, and for that reason, we need to prepare with open eyes for what might happen in if we see another period that matches what we saw in 2000-04. On the other hand, it really doesn't take much to turn things around--even a return to the period 2016-20 could work. We just don't know at this point, but need to think ahead to consider different possible outcomes.

If you want to read the entire analysis with all its mundane details, have at it. It's 13 pages long, and that's leaving out all the original spreadsheets. I'm going to guess there's about five of you who will want to read the whole report...

Here it is:

 
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Dorado

Escalante-Class Member
Seems like lower basin water use (the biggest piece of the pie) really needs to be in any discussion of scenarios to get more water in the reservoirs!
 

Greg Archer 71

Active Member
In May 2022 the USBR issued its latest 24-Month Study, which forecasts inflows and outflows for all reservoirs affecting the entire Colorado River watershed
The USBR's 'studies' are consistantly and hopelessly optimistic. That's why we're in this mess. You may as well ask your cat what the inflows/outflows are going to be.
 

JFRCalifornia

Escalante-Class Member
Seems like lower basin water use (the biggest piece of the pie) really needs to be in any discussion of scenarios to get more water in the reservoirs!
True enough, but for now I'm operating within the framework of the existing agreements among the states, which means the Lower Basin still gets its guaranteed share. At least for now. But yes, reducing Lower Basin water use would reduce the need to move as much water to Lake Mead, which in turn would allow outflows through Glen Canyon Dam to be reduced.

I'll work on that piece of the puzzle in Part 2....
 

Dougie

Well-Known Member
My take-away is that 3588 is achievable using the “mundane” 5 year average coupled with an 1800 calorie upper basin “diet” (a 10a% cut assuming standard human intake is supposed to be 2000). That’s like giving up a 2nd piece of toast at breakfast and cutting down my dessert size at dinner. Pretty achievable. Very hopeful. Now what if we can get some lower basin help? That could make 3588 even more possible in a mundane scenario.
 
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Dougie

Well-Known Member
However, planners can’t plan for the mundane to continually prevail. They must have a contingency for closer to worst case inflows (2000-2005). Is it possible to keep the lake viable (giving up on 3588 and just trying to maintain 3450 to get some north and south ramp access, forgetting power at 3490, and merging Bullfrog with Halls houseboat field?). In that 2000-2005 scenario, what dietary usage cuts would water users in upper and lower basin have to make to at least keep those 1964 water skiing levels that we see on the cover of that early AZ Highways? Are such cuts realistic, or would another very bad 5-year stretch consign us to dead pool? That is such a dark-sounding word. Correct me if I’m wrong, but I think those AZ Highways photos were taken about 3450.
 
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JFRCalifornia

Escalante-Class Member
What's the fixation with 3588?
Nothing magic about 3588, except it's a lake level that would keep the Castle Rock Cut open, plus all the other infrastructure on the lake viable--marinas, launch ramps, beaches, floating bathrooms, Rainbow Bridge access, etc...

It's also the number that's the target set up by Fill Lake Powell, the organization whose goal it is to keep Lake Powell viable as a recreational facility.


Could have picked 3590. Or 3587. But you gotta pick something.
 

JFRCalifornia

Escalante-Class Member
However, planners can’t plan for the mundane to continually prevail. They must have a contingency for closer to worst case inflows (2000-2005). Is it possible to keep the lake viable (giving up on 3588 and just trying to maintain 3450 to get some north and south ramp access, forgetting power at 3490, and merging Bullfrog with Halls houseboat field?). In that 2000-2005 scenario, what dietary usage cuts would water users in upper and lower basin have to make to at least keep those 1964 water skiing levels that we see on the cover of that early AZ Highways? Are such cuts realistic, or would another very bad 5-year stretch consign us to dead pool? That is such a dark-sounding word. Correct me if I’m wrong, but I think those AZ Highways photos were taken about 3450.
Well, the was one of the scenarios I looked at. If you had a 5-year stretch (2023-27) that was pretty similar to what happened in 2000-04, what would happen? If you went on consuming water in the Upper Basin "business as usual" (no cutbacks), annual inflow to Lake Powell would be down to about 3.5 maf each year. So even if you reduced releases each year through Glen Canyon Dam to 7 maf (way below Lower Basin delivery requirements--they'd really have to cut back on water consumption in the Lower Basin to keep Mead afloat), you'd still be running a huge net deficit in Lake Powell. You'd hit dead pool (3370) sometime in WY 2025.

Even if the Upper Basin took drastic measures (a 50% reduction in water use) and USBR released 500,000 AF extra from Flaming Gorge and the other reservoirs above Powell (dropping their storage by that much) each year, it would still be quite a hit to Lake Powell, and no power could be generated through the dam after 2024, but you could avoid dead pool. It would be down to about 3432 in WY 2027, dropping an average of 17-25 feet per year from 2023 onward.

Btw, those AZ Highways pictures (January 1964 issue) were probably taken in the summer of 1963, when the lake was in the vicinity of about 3360-3380. The lake at that level reached as far northward as about Moqui Canyon.
 
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Eagle Rock

Active Member
My take-away is that 3588 is achievable using the “mundane” 5 year average coupled with an 1800 calorie upper basin “diet” (a 10a% cut assuming standard human intake is supposed to be 2000). That’s like giving up a 2nd piece of toast at breakfast and cutting down my dessert size at dinner. Pretty achievable. Very hopeful. Now what if we can get some lower basin help? That could make 3588 even more possible in a mundane scenario.
More like getting your neighbors to give up their dessert. Including your neighbors on the other side of the tracks (i.e., east of the Continental Divide).
 

Dougie

Well-Known Member
Had no idea 3360-3380 in AZ Highways. Per the definition, it was a “dead pool” at that time, but it sure looked beautiful! I can’t apply that pejorative to this lake. It is too wonderful. I don’t fear for its future, just access, access, access. Obviously Wahweap was accessible at those levels back in 1964, so we just need to start engineering studies to grade a Stanton Road 2.5 miles out to the mouth of Bullfrog Creek with the main channel and presto! we have north access too.
 

Gunny

Active Member
Seems like lower basin water use (the biggest piece of the pie) really needs to be in any discussion of scenarios to get more water in the reservoirs!
Dorado? THIS right here! If they weren't sucking the system dry every year we wouldn't be having this discussion. Get the hell out of the desert and live where it rains once in awhile. For the life of me I can't understand what our forefathers were thinking when they thought farming/living in the desert was doable. Now everybody is paying the price. Idiots.
 

WaterMan

Well-Known Member
My take-away is that 3588 is achievable using the “mundane” 5 year average coupled with an 1800 calorie upper basin “diet” (a 10a% cut assuming standard human intake is supposed to be 2000). That’s like giving up a 2nd piece of toast at breakfast and cutting down my dessert size at dinner. Pretty achievable. Very hopeful. Now what if we can get some lower basin help? That could make 3588 even more possible in a mundane scenario.

City of Phoenix Declares Stage 1 Water Alert and Activates Drought Management Plan​


 

John P Funk

Escalante-Class Member
I can't understand what our forefathers were thinking when they thought farming/living in the desert was doable
Longer growing season for profitable crops, not that hard to understand with plentiful water. I also like to visit my aunt in Phoenix around January when it's freezing in SW Colorado. Unfortunately, recent history has proven that water isn't always plentiful. Now we know how the Anasazi felt(but they didn't have as much technology, or reservoirs).
 

Greg Archer 71

Active Member
Nothing magic about 3588, except it's a lake level that would keep the Castle Rock Cut open, plus all the other infrastructure on the lake viable--marinas, launch ramps, beaches, floating bathrooms, Rainbow Bridge access, etc...

It's also the number that's the target set up by Fill Lake Powell, the organization whose goal it is to keep Lake Powell viable as a recreational facility.


Could have picked 3590. Or 3587. But you gotta pick something.
Oh, I get the significance of that elevation now. Thanks. Can we see that in your lifetime? Or even in mine?
 
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