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The Buckhorn

Copyright (c) 2010
Winters Express
312 Railroad Avenue, Winters, CA 95694
(530) 795-4551
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Glory be!


Lake Berryessa rises 41 feet
since October to rim of Glory Hole


DEBRA DeANGELO
Express editor
Back in October, when Lake Berryessa was at its lowest point in years, compounded by lingering drought in California, no one expected that enough rain could fall to bring the lake high enough to get anywhere near the top of the Glory Hole spillway.
And then it did.
Soaking storms in December and January began steadily filling the lake, which hit its low point on Oct. 23 of last year at 855,434 acre-feet, with an elevation of 398.59 feet — 41.41 feet below the glory hole spillway, says Roland Sanford, general Manager for the Solano County Water Agency, which controls the movement of water from the lake to Putah Creek.
Sanford says even water experts weren’t expecting such a dramatic increase in the lake level because it was a “La Niña” year, which is usually a dry year, and in October, the lake was only half full, and the Glory Hole stood high and dry atop a finger of rock near Monticello Dam.
By last weekend, the Glory Hole was all but hidden, with only the 72-diameter rim visible. Crowds flocked to the Monticello Dam, hoping to catch a glimpse of the lake finally spilling over. By Sunday, the lake had risen to less than a foot from the rim, and viewers cheered when wakes from passing wakeboard boats spilled some water into the swirling funnel, but the lake still hadn’t spilled on its own.
At press time on Tuesday, Feb. 14, Peter Kilkus, publisher of the Lake Berryessa News reported that Lake Berryessa was stable at 439.4 feet at 9 a.m., and was a mere 7.2 inches below Glory Hole, putting the lake at 99.9 percent capacity. Kilkus also noted that the dam has been releasing 700 CFS for the three days prior, up from 45 CFS daily for the previous month, which is why the lake stopped rising.
At this time last year, Kilkus says the lake level was 401.2 feet — 38.2 feet lower than it was on Tuesday. The level rose 35.7 feet since Jan. 1, with a total rainfall of 34 inches recorded there and 7.3 inches added since Feb. 1.
“With this week’s predicted rainfall, the Glory Hole may spill naturally by Saturday,” says Kilkus, adding, “No wakeboard boats to help this time.”
According to Sanford, the Glory Hole’s maximum capacity in Cubic Feet per Second (CFS) is 48,000 CFS. The last time the lake spilled was 2006, said Sanford.
The visible section of the Glory Hole is 20 feet. However, the complete structure is 244 feet from top to bottom, where the spillway empties into Putah Creek. The Glory Hole gets its name from its tube shape, similar to a morning glory flower.
The highest that Lake Berryessa has ever risen above the Glory Hole is 6.70 feet, says Sanford, with a lake elevation of 446.70, recorded on March 2, 1983. At that time, the lake held 1,733,451 acre-feet in storage. The lake is considered “full” at 1.6 million acre-feet, but can rise above that level. However, it is unlikely that it would ever go over the top of the Monticello Dam, because the dam was designed to let water flow around it and out onto the road rather than go over the top. According to Sanford, the lake level would have to rise to 455 feet, which would be 15 feet over the Glory Hole rim. Sanford notes that “the Bureau of Reclamation would like to believe that (this scenario) is practically impossible.”
With the Oroville Dam poised for a catastrophic failure of its emergency spillway after the lake surpassed its capacity over the weekend of Feb. 11-12, resulting in the evacuation of nearly 200,000, naturally people in the Winters area wondered if something similar could happen here. Sanford explains that the Monticello Dam and the Oroville Dam are completely different.
The Oroville Dam is an earthen dam, while the 300-foot Monticello Dam is concaved and made of concrete set into the rocky hillsides. Compared to the emergency taking place at the Oroville Dam, Sanford says Monticello Dam is “designed for that not to happen.”
In years past, the Solano Irrigation District’s dam tender told the Express in the early 1990s that the only way Monticello Dam could fail and put Winters underwater would be a complete immediate failure along the lines of the entire structure crumbling at once, comparing it to “a blast from the Mother Ship.” In other words, the entire structure would have to fail all at once.
If such a blast should ever occur, it was estimated that Winters would be under 40 feet of water in about 15 minutes, with floodwaters reaching all the way to Davis. However, until local residents see the Mother Ship circling in the night sky, they can rest assured that what is happening below the Oroville Dam is highly improbable to happen here.
A few dam facts
Monticello Dam is located in Napa County, and was constructed from 1953 to 1957. It gets its name from the town of Monticello, which was emptied as part of the process to create Lake Berryessa. Monticello residents relocated to many areas, including Winters. The remains of the flooded town are sometimes visible when the lake is at very low levels.
The Monticello Dam power plant was completed in 1983, and is managed by the Solano Irrigation District. It supplies power to the Bay Area. Solano Irrigation District supplies the official lake level information to the Express each week.
Water is diverted from the dam approximately six miles downstream of Monticello Dam at the Putah Diversion Dam, providing irrigation to farms along the 33-mile Putah South Canal, which ends at the Terminal Reservoir, which supplies water to the city of Vallejo.
During the construction phase, Lake Berryessa did rise high enough to spill over the top of the dam when it was at about half its finished height, causing damage and delays. The Glory Hole itself is roped off and when water is spilling in, it is extremely dangerous due to suction, like that of a massive bathtub drain. Swimming is prohibited beyond the ropes. A Davis resident died in 1997 when she swam toward the Glory Hole and was sucked down the spillway.