In the green today

ndscott50

Active Member
That's a fair analysis, much appreciated. That said, my numbers come out a little differently, and don't paint quite as optimistic a picture, although it's in the same ballpark.

My first thought is this: does the 64% runoff mean April to July, or April through July? It makes a difference, although not a big one. I think ndscott50 assumed
June 30 lake level - 3541
Thanks JFR. I pulled the 4.12 from here: https://www.cbrfc.noaa.gov/wsup/graph/front/espplot_dg.html?year=2022&id=GLDA3

1649388420347.png
I believe it is for April 1 to July 31. Not sure how they are calculating their average. Either way we are in the ball park. If conditions hold we should plan on summer levels from 3535 to 3540ish. Now we have to hope for some rain/snow over the last few weeks of April and into May. Last years forecast on April 1st was not nearly as bad as it ended up. The blue line on the graph below shows the forecasted runoff by date for 2021. Last year it fell by over 1 million acre feet in April. Hopefully that was an anomaly we wont see again.
1649388838860.png
 

JFRCalifornia

Escalante-Class Member
Thanks JFR. I pulled the 4.12 from here: https://www.cbrfc.noaa.gov/wsup/graph/front/espplot_dg.html?year=2022&id=GLDA3

View attachment 17825
I believe it is for April 1 to July 31. Not sure how they are calculating their average. Either way we are in the ball park. If conditions hold we should plan on summer levels from 3535 to 3540ish. Now we have to hope for some rain/snow over the last few weeks of April and into May. Last years forecast on April 1st was not nearly as bad as it ended up. The blue line on the graph below shows the forecasted runoff by date for 2021. Last year it fell by over 1 million acre feet in April. Hopefully that was an anomaly we wont see again.
View attachment 17826
Thanks for that graph and link. Interesting. Not sure how they are calculating the average, but I'm sure it makes sense. For me, I just took the raw daily data (from the Water Database) all the way back and put it in a huge spreadsheet, so I can pretty much create any sort of dataset I need, take averages, look at trends, etc...

...but as you say, either way we are in the ballpark... Yep, it seems that a peak somewhere in the 3535-3540 range seems likely, but it's still hard to know for sure...
 

JFRCalifornia

Escalante-Class Member
...also notable that on average, about 55% of the total yearly inflow happens from April 1 to July 31. There's considerable variation in this, but the characteristic of every big year for the lake is that this figure is above 60%. And every bad year is less than 50%. And terrible years are closer to 40%. Last year it was 41%. In that great spring runoff of 2019, it was 72%--the highest percentage of spring inflow relative to total inflow on record...only 2011 was skewed to a similar degree. Even the big years of 1983-84 were only in the 61-63% range, which tells you those years had a lot of runoff in the late winter and early spring too...
 
Last edited:

Dom Tomac

Member
That's a fair analysis, much appreciated. That said, my numbers come out a little differently, and don't paint quite as optimistic a picture, although it's in the same ballpark.

My first thought is this: does the 64% runoff mean April to July, or April through July? It makes a difference, although not a big one. I think ndscott50 assumed April through July, and so here's how I see it for the same period. I agree the release schedule is 2.58 maf through that period. But the average Apr 1-Jul 31 inflow (based on the WaterDatabase) from 1991-2010 is 5.63 maf (this compares to 5.97 maf from 1965-2021). That means 64% of that 1991-2020 average is 3.60 maf, not 4.12 maf. So I calculate the net inflow as 1.02 maf, not 1.54 maf. If my numbers are right (and they could be wrong), that translates to a July 31 volume of 6.83 maf (it was 5.81 maf on April 1). And if that's true, the lake level on that date would be 3539, not 3546. Evaporation might drop that a hair. Not a huge difference, but worth noting given where the lake stands right now.

Summary:

April 1-July 31 (assumes 64% of 1991-2020 inflow)

Inflow - 3.60 maf
Outflow - 2.58 maf

Net Inflow - 1.02 maf
July 31 volume - 6.83 maf
July 31 lake level - 3539

Someone please check my analysis, and I hope I'm wrong.

Now if the forecast instead was 64% of April to July, that changes things a bit, but not much. Here's the summary of that analysis:

April 1-June 30 (assumes 64% of 1991-2020 inflow)

Inflow - 2.95 maf
Outflow - 1.78 maf

Net Inflow - 1.17 maf
June 30 volume - 6.98 maf
June 30 lake level - 3541

Bottom line is to expect to hover around 3540 in mid-summer, assuming all the above assumptions are correct.

To provide some points of comparison, here's what the April 1 - July 31 gross inflow was in recent years:

2016 - 6.0 maf
2017 - 7.4 maf
2018 - 2.3 maf
2019 - 8.5 maf
2020 - 3.4 maf
2021 - 1.7 maf
2022 - 3.6 maf (????)

Remember, the all-time average is 5.97 maf, and the 1991-2020 average is 5.63 maf. If we really end up with 3.60 maf, that's a little better than 2020, or something like 2003 or 2007 for those who remember those unremarkable, somewhat below average years. And yes, the 2021 number was the worst in the lake's history. On the flip side, in the really huge years of 1983 and 1984, that number was about 13.5+/- maf...
Thanks for your analysis. However, what's happening downstream will likely have a large negative effect on net lake level gain. The release % for Powell and Mead are both 6% behind for the year. The only reason Powell has stopped dropping over the last few days is because the outflow is at record lows. This has caused Mead to decline at unprecedented rate. Unfortunately, IMO these deficits will likely keep Powell's max below 3530.
 

JFRCalifornia

Escalante-Class Member
Thanks for your analysis. However, what's happening downstream will likely have a large negative effect on net lake level gain. The release % for Powell and Mead are both 6% behind for the year. The only reason Powell has stopped dropping over the last few days is because the outflow is at record lows. This has caused Mead to decline at unprecedented rate. Unfortunately, IMO these deficits will likely keep Powell's max below 3530.
It's true that releases are lagging and they have to make up for it, but based on BOR's schedule, they plan to do most of the "catch-up" later in the summer. So I'd still expect a peak in the upper 3530s, but then it will start to drop relatively fast by the end of July into August. Here's the BOR's planned average daily releases by month through September, all put in terms of cfs:

Apr - 8,425 cfs
May - 9,748 cfs
Jun - 11,402 cfs
Jul - 13,166 cfs
Aug - 14,429 cfs
Sep - 11,200 cfs

Now in a year like this one, you can expect inflows to return to the 6-8,000 cfs range by the end of July, so you can see what kind of net deficits the lake will be running in August, when the net outflow will probably be in the range of 7-8,000 cfs. If that's the case, expect the lake to drop about 6-8 feet in August, and maybe 5 feet in September. (rule of thumb: 0.1 ft of rise or fall with each 3500 cfs net inflow or outflow). So if I had to game this out, here's my prediction for lake levels through the summer:

Apr 30 - 3525
May 31 - 3530
Jun 30 - 3539
Jul 31 - 3537
Aug 31 - 3530
Sep 30 - 3525
 

Outside

Well-Known Member
Seems reasonable, and has the virtue of simplicity. The tricky part is determining the percentage allocation that would be fair. Should it be the current amounts (for the Lower Basin) converted to percentages, and assume a full allocation for the Upper Basin? In that case, it would be:

CA - 29.3%
AZ - 18.7%
NV - 2.0%
CO - 25.9%
UT - 11.5%
NM - 5.6%
WY - 7.0%

Or should it be based on state population? Or population within the watershed area for each state (which would greatly reduce the amount for CA and CO in particular)? Or cultivated farmland in the watershed? Or historic water use in the past 10 years (which would be ideal for the growing Upper Basin states)? Or some combination? And what about Mexico? This will be a fight.

But no matter how you slice it, the amount available for the following year should be based on a rolling 10-year average inflow for the previous ten years, or something similar to disincentivize overuse and smooth out spikes that appear in trends. But where do you measure inflow to make that determination? If it's into Lake Powell, then that allows the Upper Basin states to get an unfair upper hand, because their withdrawals would occur before that point, and thus not be considered in the rolling inflow 10-year average. How do you account for that?

Many threads to untangle, but before even considering those, first you have to untie the knot of existing water rights. How do you compensate states that will lose a portion of their existing rights, particularly CA? Do other states help subsidize the construction of water desalination plants on the CA coast in exchange for some of CA's water rights loss? What about AZ? Or other inland states that might "lose" rights? Do the other states help fund wastewater reclamation facilities in those states to offset their water loss? And if so, where is all the money coming from? There needs to be a revenue generation source for this to work for everyone. Recreation and tourist dollars might be part of the answer. Or money raised from power generation. So would reallocation of part of the federal or affected state budgets.

There will be losers in this, but I'm not sure there will be any obvious winners. Except perhaps the river, the reservoirs on the river, and those who depend on those for power, recreation and the benefits of the resources they provide.

This will be an enlightening process, but it will depend on mutual trust and cooperation among the states, not something they are necessarily known for. But it's the only wa

Here is another call I don't hear much about. From the local paper today:

Tribes assert water rights on Colorado River Basin
 

Rainbowbridge

Escalante-Class Member
Here is another call I don't hear much about. From the local paper today:

Tribes assert water rights on Colorado River Basin
Yet another aspect to consider.....with rational (hopefully) thought. My, what another interesting perspective.

In my RE lending career, I often heard: 'When there's plenty of money, (markets going up) it all works'

Kinda like....if there's plenty of water (water going up) .....(you know the rest of the 'thing').....hehehe

Challenging times reveal much.....about everything.....

:cool:
 

Trix

Escalante-Class Member
It's true that releases are lagging and they have to make up for it, but based on BOR's schedule, they plan to do most of the "catch-up" later in the summer. So I'd still expect a peak in the upper 3530s, but then it will start to drop relatively fast by the end of July into August. Here's the BOR's planned average daily releases by month through September, all put in terms of cfs:

Apr - 8,425 cfs
May - 9,748 cfs
Jun - 11,402 cfs
Jul - 13,166 cfs
Aug - 14,429 cfs
Sep - 11,200 cfs

Now in a year like this one, you can expect inflows to return to the 6-8,000 cfs range by the end of July, so you can see what kind of net deficits the lake will be running in August, when the net outflow will probably be in the range of 7-8,000 cfs. If that's the case, expect the lake to drop about 6-8 feet in August, and maybe 5 feet in September. (rule of thumb: 0.1 ft of rise or fall with each 3500 cfs net inflow or outflow). So if I had to game this out, here's my prediction for lake levels through the summer:

Apr 30 - 3525
May 31 - 3530
Jun 30 - 3539
Jul 31 - 3537
Aug 31 - 3530
Sep 30 - 3525
We don't need no stinkin' USBR.
 

Trix

Escalante-Class Member
The USGS gauge at the dam indicates the lake level is still dropping. But based on the snow water equivalent plot for the Upper Basin, and hydrographs from various rivers in Colorado, the spring runoff pulse has already started, and about a month early. This should translate into some subsequent rise at Lake Powell, although the cumulative streamflow curves are still tracking record lows west of the Continental Divide. Recall that some of this initial runoff will likely be recaptured by still-dry soils since the Upper Basin remains in drought status, and some of the rest will be retained in Upper Basin reservoirs, which are depleted. By my rough calculations, if we already passed our peak snow water equivalent value around 24 March, then the snowpack will have topped out at 83 percent of long-term average. Inner mountain stations such as Vail and Copper Mountain, after a brief shot of cold weather through tomorrow, are expected to run highs in the 40s and 50s later this week, so the runoff will continue unabated, because the snowpack as a whole has now warmed. In general, an early melt of a sub-par snowpack is not the best scenario, but we will see how it plays out.
I couldn't find that secret USGS gauge. Waterdatabase is still showing Thusday's data. USGS today?
Thanks!
 

drewsxmi

Escalante-Class Member
Having just spent a couple of days at Lake Powell, things are different, but there is still plenty of lake at 3,523' of elevation. Bullfrog Bay is more like Bullfrog Inlet, the entrance to Halls Creek is not obvious (much easier to see Lost Eden Canyon), but the main channel is still pretty much the same. The launching problems at Bullfrog and Halls could be solved with a miniscule amount of work compared to the work of trying to re-allocate water in the Colorado River Basin. It's still a beautiful lake, even if it's a little smaller.
 
Top