Glory Hole Spill Watch 2019

Glory Hole Spill Watch is Over. The “How High Will It Go” Watch Is On!

The Lake Berryessa News Drone shows history as it happens - again! Couldn’t wait to share this amazing video by FAA-certified Drone pilot, Evan Kilkus. Thanks to Marty Rodden of Lake Berryessa Boat and Jet Ski Rentals (https://lakeberryessaboats.com/) and one of our favorite musician/composrs, Bill Scholer.

Enjoy the 4K SIGHT and SOUND of literally millions of gallons of water, literally going down a drain. The North half of the San Francisco Bay Area just experienced 2 days of a direct hit from an "Atmospheric River", which soaked the Lake Berryessa watershed with 10 to 15" of rain. Lake Berryessa went up 6 feet in just 3 days, and it peaked out on February 27th, 2019 at 4.1' above the spillway, known as the "Glory Hole". (When the lake overflowed in 2017, it peaked out at 3.5' over.) The water discharge peaked this afternoon as the storm has passed. Water discharge reached about 9,500 Cubic Feet Per Second. Normal winter flow, is less than 100 CFPS. Normal Summer outflow is 500-600 CFPS. 

Lake Berryessa Boat & Jet Ski Rentals: www.LakeBerryessaBoats.com - 707-966-4204, 4420 Knoxville Rd, Napa, CA 94558 

 Song: "The Last Cool Breeze", Bill Scholer 

 Video By: Evan Kilkus

Lake Berryessa overflowed Glory Hole at 10:30 AM on Tuesday,February 26, 2019.

The lake level hit 444.1' - 4.1'  above Glory Hole at 8 AM, 2/28/19. That’s an increase of more than 5' in 24 hours!

Glory Hole drone close 022719 edited-2


In 2017 the highest point was 443.6'. Before that it was 443.5' in 2006. Highest lake level was 446.7' in 1983.

Lake Levels 1990 2017


Two day rainfall in the Berryessa Highlands was 6.8" - season total is at 36.7" as of 2/28/19. Season total rainfall at Monticello Dam is now at 31.4".

Photographic and video evidence shows the lake spilling over at 10:30 AM. However, the official measurement provided by the Solano County Water Agency at that exact moment was 439.9 feet - off by 1 inch. The “official” machine-measured time of the lake hitting 440 feet was 11:30 AM. 

Glory Hole 022619 1030AMa

The Lake Berryessa water level is officially measured on the Monticello Dam in a “stilling well” equipped with a float tape attached to a digital rotary encoder that measures to 0.01 ft.

The Glory Hole is 72 feet in diameter at lake level, 245 feet long, and narrows down to about 28 feet at the exit to Putah Creek below the dam. The rim of the structure is very flat - as can be seen from the photos and videos showing lake water spilling over at exactly the same height all around its circumference. 

Those of us who have ever used a bubble level to simply hang a picture frame should be immensely impressed by the this feat of engineering from 1956.

The fact that the calibration between the measuring device and the actual lake level is only off by one inch is amazing. The Solano County Water Agency should simply recalibrate their measuring device by one inch to increase its accuracy to match the empirical evidence. 

Precision and accuracy are often used interchangeably, but in science they have very different meanings. Measurements that are close to the known value are said to be accurate, whereas measurements that are close to each other are said to be precise.

The ideal situation is when the measurement is both accurate and precise. That happens when your eyes see the water start to flow into Glory Hole at the same time as your cell phone app shows 440 feet on the SCWA lake level web site.

Glory Hole Spill Watch: 2019

Lake Level - 2/8/19, 430’

Only 10’ To Go!

Lake Level - 9AM, 2/16/19, 436.5’ Only 3.5 Feet To Go!

Lake Level - 2/19/19, 437.2’

Only 2.8 Feet To Go!)

Lake Level - 2/22/19, 438’

Only 2 Feet To Go!

Lake Level - 2/25/19, 438.2’

Only 1.8 Feet To Go!

Lake Level - 2/26/19, 10AM, 439.2’

Only 3.5 Inches To Go!

Lake Level -  2/26/19, 10:30 AM, 440’- Berryessa is Spilling into the Glory Hole

Glory Hole Spill Watch is Over.

“How High Will It Go” Watch Is On!

As of 8 AM on 2/28/19 the lake appears to have stabilized at 444.1' - 4.1' above Glory Hole.


Lake Level as of 2/26/19, 10AM

(Glory Hole Spill Watch - Only 3.5 Inches To Go!)

On a grey, rainy Tuesday, the lake level has reached 439.7 feet. The lake level is now only 3.5 inches below Glory Hole and rising. It has rained 3.2 inches in the Berryessa Highlands since 11 AM yesterday. The water looks closer to the top because of the perspective and the fact that the Glory Hole is 70 feet wide.

According to C. Marshal, as of 10AM, February 26th, small waves are now splashing over the spillway! Technically, the lake is still abot 3" below the spillway at this time.


Thanks to Lake Berryessa Boat & Jet Ski Rental for the top photo. (https://lakeberryessaboats.com/)

and to C. Marshal for the lower photo.

See real-time lake levels at: www.scwamonitoring.com/floodmap/lakelevel1.htm    

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Lake Level as of 2/25/19

(Glory Hole Spill Watch - Only 1.8 Feet To Go!)

Lake level has slowly reached 438.2 feet - 1.8 feet below Glory Hole. It has remained at that level for the last 24 hours. With several inches of rain predicted during the next few days, it is likely that Glory Hole will spill over by Wednesday. Total rainfall has remained at 26.34 inches since February 17 when the lake level was 437.0 feet.

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Lake Level as of 2/23/19

(Glory Hole Spill Watch - Still Only 2 Feet To Go!)

Lake level remains at 438.0 feet - 2 feet below Glory Hole. It did not rise during the last 24 hours.

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Lake Level as of 2/22/19

(Glory Hole Spill Watch - Only 2 Feet To Go!)

Lake level has just hit 438.0 feet - 2 feet below Glory Hole. It only rose about 1 inch during the last 24 hours.

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Lake Level as of 2/21/19

(Glory Hole Spill Watch - Only 2.1 Feet To Go!)

Lake level appears to have stabilized at 437.9 feet - 2.1 feet below Glory Hole. There has been no rain at Monticello Dam for the last 5 days. If we get the predicted rainstorms next week, it’s possible that Lake Berryessa may spill over Glory Hole by the end of February.

Some folks may wonder how the Solano Irrigation District (SID - www.sidwater.org) and the Solano County Water Agency (SCWA -www.scwa2.com) which are responsible for the operation of the dam and the use of the water manage to get such accurate lake level and rainfall readings. See my paper on that subject (and other topics) at:

www.lakeberryessanews.com/special-publications/as-lake-berryessa-flows/as-lake-berryessa-flows-2.html

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Measuring Levels and Rainfall

The Lake Berryessa water level is actually measured on the Monticello Dam in a “stilling well”. The simplest method of measuring lake water levels is a stilling well equipped with a float tape attached to a digital rotary encoder that measures accurately to 0.01 ft.

Rainfall is measured using a tipping bucket rain gauge. However, the rain gauge on the top of Monticello Dam has never been very representative of precipitation in the overall Lake Berryessa area. The gauge is working well, but the location, surrounded by mountains on two sides with a strong up-draft coming up the canyon and over the dam, prevents getting reliable data. SCWA is considering changing this gauge location.

For example, the total rainfall measured at the dam as of 2/21/19 is 26.3 inches. But a weather station in the Berryessa Highlands (www.wunderground.com/personal-weather-station/dashboard?ID=KCANAPA84) puts total rainfall this season at 29.9 inches - a 3.6 inch difference.

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Lake Level as of 2/19/19

(Glory Hole Spill Watch - Only 2.8 Feet To Go!)

Lake level has slowly reached 437.2 feet - 2.8 feet below Glory Hole. It has remained at that level for the last 12 hours. Hwy 128 is open to Winters.

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Lake Level as of 2/18/19

(Glory Hole Spill Watch - Only 3 Feet To Go!)

Lake level has stabilized at 437 feet - 3 feet below Glory Hole. It has remained at that level for the last 24 hours. Creeks still have water but are flowing at slow rates.    

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Lake Level as of 2/17/19, 9AM

(Glory Hole Spill Watch - Only 3.2 Feet To Go!)

The lake barely continues to rise - only 3.6 inches in the last 24 hours and only 1 inch in the last 12 hours. We are not looking at any significant increase until the next storm rolls in - which will not be for at least another week. Now at 436.8 feet the level is only 3.2 feet below Glory Hole - 5.4 feet higher than its highest point last year. Total season rainfall has reached about 26.34 inches at Monticello Dam and 29.9 inches in the Berryessa Highlands.

For those of you who enjoy my statistics, during the last 7 days the lake has risen at an average of 1.5 feet per inch of rain due to steady rain and saturated ground. (6.3’ rise on 5.5” of rain) Since February 1st the lake has risen at an average rate of 10 inches per inch of rain. (8.2’ rise on 9.8” of rain)

If the coming dry spell lasts more than a few days, it will take another 1 to 2 inches of new rain before the runoff begins again - or about 5 more inches this year to spill over Glory Hole. This is likely to happen, but the actual date cannot be predicted. It could still happen in February, but that would mean a big storm series during the last week of February.

See the lake rise in real time at:

 www.scwamonitoring.com/floodmap/lakelevel1.htm

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Lake Level as of 9AM, 2/16/19

Glory Hole Spill Watch - Only 3.5 Feet To Go!

The lake continues to rise slowly - only 8 inches in the last 24 hours. Now at 436.5 feet the level is 2.4 feet higher than its highest point last year - and only 3.5 feet below Glory Hole.

Total rainfall at Monticello Dam has reached almost 27 inches for the season.    

For comparison, the rainfall in the Berryessa Highlands is always higher than at the dam and has reached 29.8 inches. But more important to the lake level is the rainfall at and above the north end of the lake. See the story and map below. If the rains keep coming as predicted, the lake may spill over Glory Hole before the end of February. Then the question will turn to how high can it go before the end of the rainy season. 

Lake Berryessa Watershed 

Rainfall measurements at the dam may not be representative of the area, but they are also not the best indicator of how fast the lake may rise. The Lake Berryessa watershed is primarily fed by Putah Creek which originates from springs on the east side of Cobb Mountain in Lake County. Putah Creek enters Napa County about 11 miles east of Middletown. 

The upper watershed encompasses the 576–square mile area upstream of Monticello Dam. Putah Creek merges with Butts Creek just before it empties into Lake Berryessa. Therefore, rainfall over the Cobb Mountain and Middletown areas provides the bulk of water entering Lake Berryessa. 

One reason that Lake Berryessa rose so quickly in 2017 was the very heavy rainfall that occurred on Cobb Mountain and the Middletown area. There is NO connection to Clear Lake.

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pKilkus@gmail.com                       © Peter Kilkus 2018