Flooding, Lake Lag, California Water situation - Printable Version

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RE: Flooding, Lake Lag, California Water situation - M T - 07-08-2024

I thought I’d give a tip of the hat to all the people involved in improving the drainage of the Houston bayou system. 

Hurricane Beryl was down to a tropical storm when it went right over Houston. The two airports got 9+ inches of rain and gusts over 80mph. All the rain stations show more than 7” with a median around 9”

But it all fell between 4am and noon. One home station near my brother’s house got 1.1” in 10 minutes, 2” in 35 minutes, 12+” in 6 hours. If there were gullys in Houston, that would be a gully washer. Nature dumped the whole rain Beryl on SE Texas!

When I caught the news about midnight (Texas time) and saw the rain amounts, I expected really bad flooding. And they did have flooding during the day. I saw an earlier flood report showing flooding likely on Brays Bayou, but by midnight all bayous were in their banks. 

Maybe it was partly due to the south-north track of the storm (roughly perpendicular to the bayous path) but I have to give credit to those that redesigned the drainage. 

Good job!

P.s. My brother installed a house generator in the last 6 months so they wouldn’t be without A/C in a situation like this. He is going to be so full of himself!  Sadly, more than 3 million households lost power and 1.8 million were still without power at 9:30pm. The company hopes to get half of those restored tomorrow.

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RE: Flooding, Lake Lag, California Water situation - Griffins78 - 07-12-2024

Due to extreme heat Lake Shasta lost 2.2 Billion gallons to evaporation in the first few days of July

https://apple.news/ArrJ-h1BrSoS_ryg1FLSifQ

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RE: Flooding, Lake Lag, California Water situation - BobK - 07-12-2024

I drive by the Shasta lakes last Weds and and again last Sunday. So very full. s is the Sacramento River up there

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RE: Flooding, Lake Lag, California Water situation - Scooter_Stepford - 07-12-2024

(07-12-2024, 07:52 AM)Griffins78 Wrote:  Due to extreme heat Lake Shasta lost 2.2 Billion gallons to evaporation in the first few days of July

https://apple.news/ArrJ-h1BrSoS_ryg1FLSifQ

That's a lot of water.

A quick internet search determined that the capacity of the lake is about 1.468 trillion gallons.  The evaporation removed about 0.1499% of the max capacity.  Not sure if that's significant from a water management perspective, but it sure makes an interesting news item...

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RE: Palo Alto Flooding - Mick - 08-18-2024

(06-14-2024, 02:01 PM)Mick Wrote:  https://cdec.water.ca.gov/

If you access the link, go to the daily statewide reservoir report, top right link. 

Reservoir capacity updated for August 17, 2024 (using threepointer's scale). Listed with % of Average to date:

Large (1 MM+ AF):
Oroville, 73% / 114%
Shasta, 70% / 110%
Pine Flat, 46% / 115%
San Luis, 43% / 107%
New Melones, 79% / 135%
Trinity, 77% / 112%
Don Pedro, 82% / 110%
Lake McClure, 79% / 131%
Berryessa, 88% / 116%
Almanor, 79% / 111%

Medium (300k - 999k AF, where available)
Folsom, 56% / 95% 
New Bullards, 77% / 106%
Diamond Valley, 94% / 126%
Millerton Lake, 52% / 88%
Isabella, 40% / 108%
Lake San Antonio, 78% / 154%
Lake Tahoe/Tahoe City, 85% / 179%
Nacimiento, 66% / 142%
Camanche, 89% / 134%
New Hogan, 63% / 142%
Castaic, 93% / 109%
Clear Lake, 47% / 115%

SF Bay Reservoirs (and of local interest, where available)
Hetch Hetchy, 92% / 102%
Calaveras, 90% / 191%
Del Valle, 47% / 95%
Lexington Reservoir, 69% / 144%
San Antonio Reservoir, 101% / 113%
Crystal Springs Reservoir, 76% / 111%

We're getting close  to the end of the water year, which runs Oct. 1 through Sept. 30.

Compared with two months ago when I ran this last, most of the reservoir capacity is down between 10% and 20%, a few precipitously (down 40% approx.). Two are up, unaccountably. It's been two relatively wet years in a row. Hope it continues...

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RE: Flooding, Lake Lag, California Water situation - M T - 08-18-2024

I guess I'm not too impressed one way or the other.  These are percents of normal.  So, if we're above normal, that's kinda to be expected since we were above normal previously.  

I think it would have been good if we were tracking the total amount of water.  At least in theory, water from Pine Flat (144% -> 117%) could have been used while preserving water in New Melones (140% -> 135%).

I expect there were usage demands that had been pent-up or deferred in the drought years (I'm mainly thinking of agricultural use).  I certainly know that is so at my house.  You tighten the belt in drought years, but then loosen it in wet years.  So "normal" usage may be less than what would really be normal.

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RE: Flooding, Lake Lag, California Water situation - Leftcoast - 08-18-2024

Most California reservoirs have dual purposes - Water Storage and Flood Control.  Reservoirs with a flood control objective will drop their water level swiftly prior to the next rainy season so they can capture any unexpected early run-off.  

A flood control manager's nightmare is a steady, drenching atmospheric river hitting the Sierra's before they've created needed capacity in the reservoirs.  (Or alternatively, an early, heavy snowfall followed by a pineapple express/warm rainfall).  I'm also hearing that they are planning for a higher snow line now due to warming trends which means that more of the water from those rivers goes straight to run-off and isn't stored as snow.

You'll see most reservoirs dropping water in the next two months. Given the last two years experience and newer warming models they are likely to start earlier than in the past.

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RE: Flooding, Lake Lag, California Water situation - Mick - 08-19-2024

What happens to water released from reservoirs? Groundwater recharge, rebuild other lakes and rivers, runs out to the ocean...what happens?

This is an interesting article on water release policy.

https://www.kqed.org/science/549358/california-reservoirs-are-dumping-water-in-a-drought-but-science-could-change-that

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RE: Flooding, Lake Lag, California Water situation - Mick - 08-23-2024

Might get snow above 8,000 feet in the Sierras this weekend. Haven't seen August snow in that area in at least 20 years.

https://www.msn.com/en-us/weather/topstories/a-rare-august-storm-may-bring-snow-to-california-s-high-sierra-what-to-know/ar-AA1pgasc

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RE: Palo Alto Flooding - Mick - 10-03-2024

(08-18-2024, 08:35 AM)Mick Wrote:  https://cdec.water.ca.gov/

If you access the link, go to the daily statewide reservoir report.

The "water year" runs from October 1 through the following September 30, so we just started a new year. Reservoir capacity updated for October 3, 2024 (using threepointer's scale). Listed with % of Average to date, and the % change from six weeks ago:

Large (1 MM+ AF):
Oroville, 55% / 98% / (-16%) 
Shasta, 61% / 109% / (-1%)
Pine Flat, 40% / 134% / (+19%)
San Luis, 50% / 116% / (+9%)
New Melones, 76% / 137% / (+2%)
Trinity, 70% / 115% / (+3%) 
Don Pedro, 75% / 109% / (-1%)  
Lake McClure, 68% / 141% / (+10%)  
Berryessa, 85% / 117% / (+1%) 
Almanor, 70% / 109% / (-2%) 

Medium (300k - 999k AF, where available)
Folsom, 47% / 94% / (-1%) 
New Bullards, 67% / 106% / (0%)
Diamond Valley, 97% / 131% / (+5%)
Millerton Lake, 47% / 100% / (+12%)
Isabella, 29% / 102% / (-6%) 
Lake San Antonio, 74% / 156% (+2%)
Lake Tahoe/Tahoe City, 74% / 197% / (+18%) 
Nacimiento, 56% / 144% / (+2%) 
Camanche, 86% / 141% / (+7%)
New Hogan, 57% / 149% / (+7%)
Castaic, 85% / 103% / (-6%) 
Clear Lake, 28% / 115% / (0%)

SF Bay Reservoirs (and of local interest, where available)
Hetch Hetchy, 80% / 101% / (-1%)
Calaveras, 88% / 197% / (+6%)
Del Valle, 42% / 95% / (0%)
Lexington Reservoir, 55% / 148% / (+4%)
San Antonio Reservoir, 99% / 113% / (0%)
Crystal Springs Reservoir, 75% / 113% / (+2%)

Sixteen up, eight down, five unchanged. Starting the year pretty strong, I think. 

But will this be a wet or dry winter? Six weeks ago, ABC reported a weak to moderate La Nina (74% chance of development between Nov and Jan), with an overall trend for dry conditions for California.
La Nina Update: What to expect for California weather | abc10.com

California water officials think we'll be back in a drought:
California water officials warn La Niña could bring dry winter - E&E News by POLITICO (eenews.net)

From Dept of Water:
California Prepares for Extreme Weather Swings as New Water Year Approaches

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RE: Flooding, Lake Lag, California Water situation - M T - 10-03-2024

Btw, re: "California water officials think we'll be back in a drought".  As I read the free part of that article, it is not that they think we'll be back in a drought, it is that they warn California COULD go back into a drought.  Officials need to plan for the full range of possibilities.  It is appropriate that they warn and consider the possibility of a drought even if they don't plan for one.

So, stepping back and thinking about this a second.  After two wet years (and an exceptionally hot, typically dry, summer), we are only a bit above historical averages. 

What I wish I knew (current & historical):
  How much water was let out of the reservoirs (making room for incoming water) that could have been saved had there been more storage.
  How is the water being used:  Household water, industrial water, farming, ecological usage (preserving estuaries, etc), runoff to the ocean, power generation, etc.
  If no rain or snow fell, how long do the reservoirs last.

Is the historical average meaningful when we draw down more water today (than in the years comprising the average) for the ways it is being used  (such as increase in population, household irrigation, farm irrigation, etc.)

Using the charts linked from https://cdec.water.ca.gov/water_cond.html
I find the data in the "Current Water Year <location> Precipitation Index Chart" interesting to consider.
Averaging the last two years versus the Average (1991-2020) rainfall:
Northern Sierra:  57.4  vs  53.2   (+4.2 = +7.9%)
San Joaquin:  48.8 vs 39.9  (+ 8.9 = +22.3%)
Tulare Basin:  38.5 vs 28.3  (+ 10.2 = +36.0%)

This year's snowpack (dark blue line in "Current Year Regional Snow Sensor Water Content Chart") tracked the "average" quite closely for North, Central, and South.  Last year's (yellow) was about double the average.  Averaging over the two years would be about 50% above average.

And, yet, here we are, being concerned about a possible lower than average year....

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RE: Flooding, Lake Lag, California Water situation - Mick - 10-03-2024

(10-03-2024, 11:21 AM)M T Wrote:  Btw, re: "California water officials think we'll be back in a drought".  As I read the free part of that article, it is not that they think we'll be back in a drought, it is that they warn California COULD go back into a drought.  Officials need to plan for the full range of possibilities.  It is appropriate that they warn and consider the possibility of a drought even if they don't plan for one.

So, stepping back and thinking about this a second.  After two wet years (and an exceptionally hot, typically dry, summer), we are only a bit above historical averages. 

What I wish I knew (current & historical):
  How much water was let out of the reservoirs (making room for incoming water) that could have been saved had there been more storage.
  How is the water being used:  Household water, industrial water, farming, ecological usage (preserving estuaries, etc), runoff to the ocean, power generation, etc.
  If no rain or snow fell, how long do the reservoirs last.

Is the historical average meaningful when we draw down more water today (than in the years comprising the average) for the ways it is being used  (such as increase in population, household irrigation, farm irrigation, etc.)

Using the charts linked from https://cdec.water.ca.gov/water_cond.html
I find the data in the "Current Water Year <location> Precipitation Index Chart" interesting to consider.
Averaging the last two years versus the Average (1991-2020) rainfall:
Northern Sierra:  57.4  vs  53.2   (+4.2 = +7.9%)
San Joaquin:  48.8 vs 39.9  (+ 8.9 = +22.3%)
Tulare Basin:  38.5 vs 28.3  (+ 10.2 = +36.0%)

This year's snowpack (dark blue line in "Current Year Regional Snow Sensor Water Content Chart") tracked the "average" quite closely for North, Central, and South.  Last year's (yellow) was about double the average.  Averaging over the two years would be about 50% above average.

And, yet, here we are, being concerned about a possible lower than average year....

Could part of that concern be founded in the drying up of the Colorado River and other out-of-state water resources?

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RE: Flooding, Lake Lag, California Water situation - Mick - 11-11-2024

San Luis Reservoir will soon expand by 130,000 acre feet, enough for 650k people for a year. Meaning they will raise the 382 foot dam walls by 10 feet.

Santa Clara Valley Water District will come up with slightly less than half of the funding ($435 mms.). Total cost, $942 mms.

Deal reached to expand massive reservoir near Bay Area to increase water supplies

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RE: Flooding, Lake Lag, California Water situation - M T - 11-12-2024

(11-11-2024, 07:52 PM)Mick Wrote:  San Luis Reservoir will soon expand by 130,000 acre feet, enough for 650k people for a year. Meaning they will raise the 382 foot dam walls by 10 feet.

Santa Clara Valley Water District will come up with slightly less than half of the funding ($435 mms.). Total cost, $942 mms.

Deal reached to expand massive reservoir near Bay Area to increase water supplies

Quote:Under the deal, the Santa Clara Valley Water District, a San Jose agency that provides water to 2 million residents in Santa Clara County, would contribute $435 million [46%] of the $942 million cost of the project. It would receive the largest share of the new water, 60,000 acre feet [46%].
...
Under the deal, the federal government will put up 30% of the funding and receive 30% of the new storage space in the reservoir, or 39,000 acre feet. The eight water agencies will contribute 70% of the funding and receive 91,000 acre feet [70%]. Construction would begin in 2027 and end in 2032, overseen by the Bureau of Reclamation.
...
Other agencies that would receive some of the water are the massive Westlands Water District in Fresno, the Byron Bethany Water District in Contra Costa County, the city of Tracy, the San Benito County Water District and the Del Puerto, San Luis and Pacheco water districts.

IIUC, this will increase the capacity by about 6.5%.  But the numbers given are for storage capacity, not flow.

How much of the current water (outflow) is earmarked for So.Cal. municipal systems,  Central Valley farmers?
Where does the 30% new capacity for the Federal Government go?

I don't quite understand how this works. Sure, it will hold more water when full.  But how much does S.C. County get each year?  Is there sufficient inflow to fill it each year?  It seems there has been in the last few years, but go back 3 years and it was about 100' lower than today.   If it isn't full, will S.C.C. get a proportional share, or will SoCal and the farmers get first dibs.

It seems this reservoir is managed to maintain a level of about 100' lower than the top of the dam.   In 2019, it was within 50' of its capacity only for 4.5 months.  The next year, only a month.  From May 2020 to March 2023, it never got within 50'.  From October 2023 to now, it hasn't been within 50' of capacity.    I kinda wonder what good the extra 10' will do.  If we get the rains/snow of 2023 each year, great.  But even those rains didn't help the reservoir for a year.

Has SCC already acquired the money for this?

It seems like a reasonable deal if SCC is guaranteed 6.5% * 60% of the outflow.

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RE: Flooding, Lake Lag, California Water situation - Mick - 11-12-2024

(11-12-2024, 04:02 AM)M T Wrote:  

(11-11-2024, 07:52 PM)Mick Wrote:  San Luis Reservoir will soon expand by 130,000 acre feet, enough for 650k people for a year. Meaning they will raise the 382 foot dam walls by 10 feet.

Santa Clara Valley Water District will come up with slightly less than half of the funding ($435 mms.). Total cost, $942 mms.

Deal reached to expand massive reservoir near Bay Area to increase water supplies

Under the deal, the federal government will put up 30% of the funding and receive 30% of the new storage space in the reservoir, or 39,000 acre feet. The eight water agencies will contribute 70% of the funding and receive 91,000 acre feet [70%]. Construction would begin in 2027 and end in 2032, overseen by the Bureau of Reclamation.
...
Other agencies that would receive some of the water are the massive Westlands Water District in Fresno, the Byron Bethany Water District in Contra Costa County, the city of Tracy, the San Benito County Water District and the Del Puerto, San Luis and Pacheco water districts.

Quote:IIUC, this will increase the capacity by about 6.5%.  But the numbers given are for storage capacity, not flow.

How much of the current water (outflow) is earmarked for So.Cal. municipal systems,  Central Valley farmers?
Where does the 30% new capacity for the Federal Government go?

I don't quite understand how this works. Sure, it will hold more water when full.  But how much does S.C. County get each year?  Is there sufficient inflow to fill it each year?  It seems there has been in the last few years, but go back 3 years and it was about 100' lower than today.   If it isn't full, will S.C.C. get a proportional share, or will SoCal and the farmers get first dibs.

It seems this reservoir is managed to maintain a level of about 100' lower than the top of the dam.   In 2019, it was within 50' of its capacity only for 4.5 months.  The next year, only a month.  From May 2020 to March 2023, it never got within 50'.  From October 2023 to now, it hasn't been within 50' of capacity.    I kinda wonder what good the extra 10' will do.  If we get the rains/snow of 2023 each year, great.  But even those rains didn't help the reservoir for a year.

Has SCC already acquired the money for this?

It seems like a reasonable deal if SCC is guaranteed 6.5% * 60% of the outflow.

The San Luis Reservoir has been full three times over the past 12 years. It's located between Gilroy and Los Banos and is the fifth largest reservoir in the state. Eight separate water agencies reached a deal with the Federal government to increase the reservoir's size. Under the deal, the Santa Clara Valley Water District, a San Jose agency that provides water to 2 million residents in Santa Clara County, would contribute $435 million [46%] of the $942 million cost of the project. It would receive the largest share of the new water, 60,000 acre feet [46%].

Bing Videos

The extra 60,000 af are approximately three times the size of Lexington Reservoir. Fun fact: San Luis Reservoir is the largest off-stream reservoir in the United States. From Wikipedia: An off-stream reservoir is a reservoir that is not located on a streambed, and is supplied by a pipeline, aqueduct or an adjacent stream. San Luis Reservoir is the largest off-stream reservoir in the United States. Although it is located on a small stream, it gets the vast majority of its water from the California Aqueduct by pumping aqueduct water up-hill to the reservoir.

Deal reached to expand massive reservoir near Bay Area to increase water supplies | News & Features | ArcaMax Publishing

Deal to expand reservoir should boost California's water supply | KTVU FOX 2

Here's a photo of the reservoir from March 30, 2023:



And this photo is from September, 2024:

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RE: Flooding, Lake Lag, California Water situation - M T - 11-12-2024

10% full in 2016
  (story)
2014

July 2021

This video has a number of images of the lake over time.

I did find a reference to it being full only 3 times in its existence, but I think that's just a management decision.  So, I still question what good the extra 10 feet will do.

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RE: Flooding, Lake Lag, California Water situation - Leftcoast - 11-12-2024

Per Mick's table showing San Luis at 99% the lake was most recently at capacity on June 15, 2023. 

The main value of expanding San Luis is the ability to "bank" water during the big rain years like 2023.  Expansion provides almost no flood control value and it's unclear to me if it will do much to expand the dam's electricity generation capability.

June 15, 2024
Large (1 MM+ AF):
San Luis, 99% / 159%

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RE: Flooding, Lake Lag, California Water situation - BostonCard - 11-18-2024

First major storm and atmospheric river headed to California, and it’s going to be a doozy…

https://www.sfchronicle.com/weather-forecast/article/bomb-cyclone-atmospheric-river-rain-california-19923845.php

BC

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RE: Flooding, Lake Lag, California Water situation - cardcrimson - 11-18-2024

(11-18-2024, 03:41 PM)BostonCard Wrote:  First major storm and atmospheric river headed to California, and it’s going to be a doozy…

https://www.sfchronicle.com/weather-forecast/article/bomb-cyclone-atmospheric-river-rain-california-19923845.php

BC

Great. Looks like I'll be on the roof tomorrow blowing off the leaves, and they're not all down yet. . .

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RE: Flooding, Lake Lag, California Water situation - 82lsju - 11-19-2024

Quote:A new study from Stanford researchers shows central California’s vast San Joaquin Valley has sunk at a record pace since 2006. Strategic recharging of aquifers could help slow or stop the sinking.

https://news.stanford.edu/stories/2024/11/groundwater-pumping-drives-rapid-sinking-in-california?utm_content=httpsnewsstanfordedustories202411groundwaterpumpingdrivesrapidsinkingincalifornia

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