JFRCalifornia
Keeper of San Juan Secrets
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.
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.
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but either way it's sure nice not to be talking about dead power pool and possible marina closings and crap like that! I guess it could be the long way around antelope all summer but that's ok too, it might help keep the crowds down up lake, that and no fuel up there. That all could change by next year so I'd see that as a last chance for some solitude. That part has been nice
