Spring Runoff Reality Check - May 7

Status
Not open for further replies.
AndyMAC said:
is this the Central Colorado side or the southerhern? Cause i know the upper Green side of the Unitahs and the Manti-Lasal is still very loaded at upper elevations too.
Click to expand...
According to the Snow Data on the Lake Powell Water Database the Upper Colorado River Basin has 9 inches of SNE(Snow Water Equivalent) which is 142% of normal at this time.
The Upper Green River Basin has about 6 inches of SNE and that is 176% of normal. There is also a considerable amount of snow on the Yampa/White river basin that eventually flows into Lake Powell.
The lower elevation and more southerly river basins like the San Juan are mostly at or close to zero.
 
Last edited:
JFRCalifornia said:
I've been seeing a lot of concern on this forum about the runoff being less than hoped, and how that means doomsday is right around the corner. Let me untangle the most recent data we have and put it into perspective, and give you my take on what it all more realistically adds up to.

First off, let's look at how April played out compared to what USBR predicted based on NOAA's information:

USBR projected April inflow - 645,000 af
Actual April inflow - 659,000 af

USBR projected April 30 lake level - 3559.4
Actual April 30 lake level - 3559.8

All right, so Lake Powell actually outperformed what USBR thought would happen in April. Okay, so what about May?

USBR projected May inflow - 1.63 maf
USBR projected May 31 lake level - 3572.1

It's way too early in May to know whether or not the reservoir performs as predicted. May is almost always the "make-or-break" month, but you almost never know what it will end up like until you're more than halfway through the month. That's what the record shows. To me, the key indicators for this year are still reasonably good:

1. In 2024, the outflow so far has been exactly as USBR has planned, which in historic terms is very low--good for Lake Powell. For May, USBR is essentially going to match outflows we saw in April. That means about 600,000 af, or roughly 9700 cfs on average each day. That's pretty much exactly what we're seeing so far in May.

2. For inflow to reach the USBR-projected 1.63 maf, that means an average of 26,500 cfs each day. Totally achievable. This year looks a lot like 2015 or 2016, very average years. In 2015, May started out with less than 10,000 cfs, and increased to over 30,000 cfs by the end of the month--inflow for the month was about 1.4 maf. May 2016 was a little better, starting at 17,000 cfs and peaking at just over 50,000 cfs that month--total inflow was about 1.9 maf. Seems reasonable we'll end up somewhere in between, which would be right in line with what USBR projects. These recent shots of rain and snow could bump that just a bit, hard to say, but let's not count on that.

3. The Upper Basin SWE is now right on the median for this date, and in general the sub-basins are pretty much in the same boat, plus or minus. Again, this all is in line with what USBR has been projecting.

4. Then there's the CBRFC water supply projection, which is really the key data set that forms the heart of USBR's guesses. On May 1, the official "median" projection for April 1-August 1 was 5.1 maf. On May 7, that's up to 5.4 maf. Is that correct? Who knows, but I'm guessing that CBRFC knows better than any of us. Of course, their latest (April) 24-Month Study was based on 5.7 maf of water supply through July, so we're still 0.3 maf short of that. If that's really true, and if they keep their operations as planned, then instead of the peak of 3589 they predicted, we're looking at something closer to 3585.

Of course, all that could be wrong--still way too early to tell. As I say, let's revisit this question on May 20. We'll know much better then. But one thing's for certain--it's way too early to start writing this runoff year off yet.
Click to expand...
Looks like we missed the USBR projected lake level for May. What are your thoughts on where we are now with the runoff?
 
Paul_G said:
Looks like we missed the USBR projected lake level for May. What are your thoughts on where we are now with the runoff?
Click to expand...
I keep coming back to the CBRFC projection of how much water supply is left in the watershed from April through July. It’s the number that USBR bases its projections on in its monthly report (24-Month Study). USBR’s latest report was based on a May 1 CBRFC forecast of 5.1 maf of unregulated flow into Lake Powell during that period. After May 1, that number rose a bit after some unexpected late season snow. It’s now back down to near 5.1 maf and likely to stay there. The number is updated daily.

Based on that, I’d say that USBR’s latest guess that the lake will peak at just over 3583 is still likely accurate. I say that because the upper reservoirs are nearly full, so the water will mostly pass through them. I also say that because of the cool May, inflow to Powell has been unusually even and holding at just over 30,000 cfs. I think this means the runoff will tend to be steady into June, rising a little, but eventually getting to 3583 without a huge peak rise. It’s going to continue to go up because USBR has kept outflows remarkably low for the month of May, and June outflow is only expected to rise by about 5% over May levels.

You can talk about remaining snow at high elevations, or the lack of it depending on where you are, but that’s my best guess with the data we currently have.
 
JFRCalifornia said:
I keep coming back to the CBRFC projection of how much water supply is left in the watershed from April through July. It’s the number that USBR bases its projections on in its monthly report (24-Month Study). USBR’s latest report was based on a May 1 CBRFC forecast of 5.1 maf of unregulated flow into Lake Powell during that period. After May 1, that number rose a bit after some unexpected late season snow. It’s now back down to near 5.1 maf and likely to stay there. The number is updated daily.

Based on that, I’d say that USBR’s latest guess that the lake will peak at just over 3583 is still likely accurate. I say that because the upper reservoirs are nearly full, so the water will mostly pass through them. I also say that because of the cool May, inflow to Powell has been unusually even and holding at just over 30,000 cfs. I think this means the runoff will tend to be steady into June, rising a little, but eventually getting to 3583 without a huge peak rise. It’s going to continue to go up because USBR has kept outflows remarkably low for the month of May, and June outflow is only expected to rise by about 5% over May levels.

You can talk about remaining snow at high elevations, or the lack of it depending on where you are, but that’s my best guess with the data we currently have.
Click to expand...
Fingers crossed we still get over the 3580 mark. Thank you for the rundown JFR!
 
RobertGosselin said:
According to the Snow Data on the Lake Powell Water Database the Upper Colorado River Basin has 9 inches of SNE(Snow Water Equivalent) which is 142% of normal at this time.
The Upper Green River Basin has about 6 inches of SNE and that is 176% of normal. There is also a considerable amount of snow on the Yampa/White river basin that eventually flows into Lake Powell.
The lower elevation and more southerly river basins like the San Juan are mostly at or close to zero.
Click to expand...
I wouldn’t put a lot of faith in the snow data, SWE’s are not really very meaningful this late in the season. As many stations approach 0, it is easy to generate super high, whacky numbers. That is why they appear with asterisk next to them on the SNOTEL websites with a disclaimer..

I am still hopeful that we will end up with a decent runoff however!
 
thank you JFR it’s always interesting reading what you have to say. To say you’re a man of great wisdom and insight would be an understatement! Good day to all.
 
Last edited by a moderator:
Oh yah I forgot about the Question I had regarding dumping water out of Blue Mesa.. So if they are dumping water out of Blue Mesa does that mean it’s going down river into Powell, or is it being wasted by dumping into something else if that is even possible?
 
Last edited by a moderator:
Jon.Diedrich said:
Oh yah I forgot about the Question I had regarding dumping water out of Blue Mesa.. So if they are dumping water out of Blue Mesa does that mean it’s going down river into Powell, or is it being wasted by dumping into something else if that is even possible?
Click to expand...
No, Blue Mesa flows the Gunnison Drainage which all meets up near Grand Junction and flows to LP
 
Last edited by a moderator:
Jon.Diedrich said:
Oh yah I forgot about the Question I had regarding dumping water out of Blue Mesa.. So if they are dumping water out of Blue Mesa does that mean it’s going down river into Powell, or is it being wasted by dumping into something else if that is even possible?
Click to expand...
There are two very small reservoirs just downstream of Blue Mesa on the Gunnision—Morrow Point and Crystal. They collectively have a capacity of about 0.14 maf and are currently mostly full, so water released from Blue Mesa is likely to pass through them and onto Powell, except for water lost to evaporation or seepage…

As for the “wisdom” comment, I appreciate that, but you’re also talking about the guy who just ran out of gas on Lake Powell…

You might want to re-think that assessment…
 
A man called horse said:
Story in local paper today says the San Juans & LaPlatas have given their all. Whats left will sublimate.
Click to expand...
Durango Herald is humorous at best. The Animas was stated as peaking on 5/21 at 2280 cfs as well and yesterday it hit 2710 cfs. It will likely go over 5' today. I live in Hesperus and there is plenty of white looking north and it will come at us quickly with the heat coming this week.
 
>>>Powell, except for water lost to evaporation or seepage…

Don't forget all the irrigation ditches siphoning between Blue Mesa and the border of Utah.

off topic but I recently heard(but haven't verified) that irrigated land from the Gunnison Tunnel cannot transfer the water rights. The land comes with the water, period. These water rights precede the 1922 Compact.

Just trying to grasp the future consequences should the drought worsen and the Lower Basin States come after "their" water
 
Lake went up 4.5 ft last week. Seems like it is on track for another couple weeks of similar inflow and based on historical data it peaks just after the 4th of july. 3583 seems very likely to me if not a few feet higher.

Does anyone know how many more feet the lake has to go up for the walking ramp at Antelope point to be usable again? We were there two sundays ago and it was 6-8 ft from being usable but the lake went up 5ft since then. How close is it this week?
 
Thanks to JFR for all your time, knowledge, very detailed stories & analysys... I do have a quick question though- what;s your best guess for Lake Mead's peak this year? Having recently moved near there it's interesting to hear some of the local naysayers talk about it dropping another 10-15ft this year. IMO they listen to the NPS too much... as far as running out of gas at Powell recently JFR, blame it on the rental boat!!! Best excuse yet! LOL
 
What a cruel tease mother nature is this year. 3580, Really? I'll take it but that's a painful number, not as painful as 3525 but cruel all the same.(so close to filling the cut) Oh well, backing the houseboat out at 5:00 am and into the maytag straights early it is. Not the end of the world, Powell is still worth it but I hope they're wrong about the high point
 
Last edited:
Status
Not open for further replies.
Back
Top