Spring Runoff Reality Check - May 7

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WaterMan said:
Sunrise runs into the Salt River then to Roosevelt Lake. In a way this snow still helps Powell, the more water for the SRP the less Phoenix and Tucson needs from the Colorado system.
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I could've sworn that area ran north to the LCR into the grand canyon...I could be wrong but the shed maps i've seen pointed me that direction.
 
We are going far astray of OP, as often happens. Best I can tell, Andy is right that Sunrise flows to Colorado River. I used River Runner app, which I think found on another WW post. It shows that a drop of water at the ski resort flows to Colorado River.
I have tried a couple of times to attach the link to River Runner that has the origination at the ski resort, but it keeps defaulting to Flagstaff. Anyway, one can x out of Flagstaff, zoom in on the satellite map to find the ski resort, click on that point and it follows the flow to Colorado River. Surprising.
river-runner.samlearner.com

River Runner

Watch the path of a raindrop from anywhere in the contiguous United States
river-runner.samlearner.com river-runner.samlearner.com
 
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Looking at UC snowpack graphs, this past week or so produced a wobbling horizontal line getting us to about 100% SWE for the date. Don’t see that horizontal curve in any of previous years. Looks good to me!

Hah, edit. Today the percent dropped abruptly to 96%. Significant change on the smaller base.
 
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Maybe this has been explained somewhere already and let me know if it has. But it sure seems like inflows for this time of year are much lower than expected. Does anyone have an explanation for this? Has it been a cooler spring and the real melt just hasn’t started yet? I just have a really hard time believing the “dry soil is eating all of the runoff up” like they have been saying for years. but maybe I’m wrong?
 
Well, Zach, you are generally right that slow runoff has been discussed before, and we need to discus it again! That’s what we do.😀. As you and I have wondered, why 33% river levels with 95% of avg SWE? Gotta be the cool weather and recent flurries, which should be a good thing. But windy throughout the 4 corners, grrr. Our hydrological wizards will likely give us a remedial explanation and we’ll learn the years similar to this.
I guess I shouldn’t take these guys for granted, but they never disappoint us.
 
Trix said:
Well, Zach, you are generally right that slow runoff has been discussed before, and we need to discus it again! That’s what we do.😀. As you and I have wondered, why 33% river levels with 95% of avg SWE? Gotta be the cool weather and recent flurries, which should be a good thing. But windy throughout the 4 corners, grrr. Our hydrological wizards will likely give us a remedial explanation and we’ll learn the years similar to this.
I guess I shouldn’t take these guys for granted, but they never disappoint us.
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There’s still a lot of snow above 10,000 feet. I live at 8,200ft on the East side of the divide in CO. It’s been a pretty cold spring so far. Lots of cold nights as well. It seems to me like runoff was starting to ramp up a few weeks ago and then it got cooler again with more snow and rain.
The wind has been incredible as well. So hopefully that’s not as big of a factor in lower runoff flows as some suspect.
 
Yes, runoff seems to be lagging, but a cool May will do that. It’ll come. USBR just released its latest 24-month study, and now they think the lake will peak at somewhere just under 3584 in early July. That’s pretty much what I thought they’d come up with based on the CBRFC May 1 prediction of 5.1 maf of water supply from April to August. The good news is that because of recent snowfall, that number has crept up to about 5.4 maf. If that number holds (big if), then expect the lake to peak closer to 3586, maybe 3587. If it falls back to 5.1, then it will be about 3584.

Without going through the math and lake level charts to see how the sausage is made, a quick way to gauge where the lake will peak is like this:

1. Follow the CBRFC for unregulated water supply numbers for April-July.

2. If the number ends up at 5.1 maf, the USBR’s May 2024 forecast will likely be right—peak about 3584. It was 5.1 on May 1, hence their latest prediction.

3. For every additional 100,000 af predicted by CBRFC, add a foot to the lake’s peak. So 5.2 maf suggests a peak of about 3585, and 5.7 maf would mean about 3590. That number fluctuates every day, but the variability is decreasing, so it’s not likely at this point to radically change…
 
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What has me baffled the most is the flows of the San Juan. In late March, the lower San Juan snowpack peaked at something like 120% of median. Now, all the snow has melted, but the San Juan hasn't been above about 40% of average flows this year. What happened to all that snow? I get that we had no monsoon last year, but my little brain just can't imagine that all that snow went right into the ground. Anyone have any insight?
 
baldboater said:
What has me baffled the most is the flows of the San Juan. In late March, the lower San Juan snowpack peaked at something like 120% of median. Now, all the snow has melted, but the San Juan hasn't been above about 40% of average flows this year. What happened to all that snow? I get that we had no monsoon last year, but my little brain just can't imagine that all that snow went right into the ground. Anyone have any insight?
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Navajo has not been releasing, letting it fill & NAPI is running thousands of acres center pivot pumped from the San Juan. From my dining room window theres still snow in the San Juans & my view is the south sude.
 
A man called horse said:
Navajo has not been releasing, letting it fill & NAPI is running thousands of acres center pivot pumped from the San Juan. From my dining room window theres still snow in the San Juans & my view is the south sude.
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Which is pretty sad as Navajo is only up 5' from the low point this year and down 12' from last year. Been so dang cold at night so it just feels like run off is just slowly dissipating honestly. Animas river is basically clear and mild flow...
 
viking842000 said:
Which is pretty sad as Navajo is only up 5' from the low point this year and down 12' from last year. Been so dang cold at night so it just feels like run off is just slowly dissipating honestly. Animas river is basically clear and mild flow...
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The flow in the San Juan has been weak this spring and is not likely to pick up very much. There is only 2.4 in of SWE left in the headwaters and that is about 25 % of normal at this time in the runoff cycle. It doesn't look like the San Juan is going to contribute much to Lake Powell this year since the majority of the flow is going into Navajo and Vallecito lakes. The good news is that the Colorado River Headwaters have lots of snowpack remaining. They are still at about 13 in of SWE which is 130% of normal.
The rivers feeding the lake are finally starting to crank at 25K cfs so the lake should be showing 6 in rises per day soon. This is a bad time for the daily rise data to be absent. They are 4 days behind in posting the current levels of the lake.
 
Robert, I assume “they” is the Lake Powell Water Database. No idea why it’s not updating. At the bottom of the WW homepage links is the USGS Lake Powell Monitor. Today at 8:30 is shows 3562.5, up only a couple of tenths from LPWD last Thursday.
 
Trix said:
Robert, I assume “they” is the Lake Powell Water Database. No idea why it’s not updating. At the bottom of the WW homepage links is the USGS Lake Powell Monitor. Today at 8:30 is shows 3562.5, up only a couple of tenths from LPWD last Thursday.
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Thanks for that info. I thought I had explored everything the Lake Powell Water Database had to offer. The rivers above the lake have jumped up in the past 2 days. It usually takes 3 or 4 days before they reach the lake so I would expect to see the greater increases in a day or two.
 
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