Department of Water Resources
A daily compilation for DWR personnel of significant news articles and comment
October 14, 2008
1. Top Items -
Low lake levels impact electric generation
By MARY WESTON - Staff Writer
OROVILLE -- Low water elevations at
The power plant located underground near the dam is a pumping and power-generating facility. Operated by the California Department of Water Resources, the plant produces electricity to pump water for the State Water Project.
Maury Miller, superintendent of the DWR operations office in Oroville, said lake levels impact power generation.
There are six generators at the power plant, and two of them are out of service because of the lake level, currently about 677 feet.
Oroville has one of the three pumping-generating plants in the State Water Project. Six generators pump water through the Oroville facilities and generate electricity.
"Obviously, there's an impact because we can't generate at capacity," Miller said.
The generators have different operation requirements, so the units are checked often during low water levels.
If a generator starts vibrating too much to operate safely, it's taken out of service, he said.
Tuan Bui of the State Water Project Power Management and Optimization branch said the water project is a "net quantity consumer," which means the project buys more water than it generates on a day-to-day basis.
Water is piped from the lake to the generators at the Hyatt Power Plant. During low lake elevations, it's more difficult to pump the water because of decreased water pressure, Bui said.
However, the value of power generation lost during low lake elevations is difficult to calculate, said Don Strickland of DWR.
"We don't produce power to make money," he said.
The State Water Project doesn't pump water during peak power usage times in exchange for higher electricity use in off-peak hours.
In Oroville, DWR maximizes power generation by pumping water through the generators at the powerhouse, storing it in the Thermalito Forebay and Afterbay, then pumping it back to the lake and through the generators at the powerhouse again, Strickland said.
"It's near impossible to put a dollar figure on Hyatt generation," Strickland said, "since DWR doesn't produce power for sale, only for running the SWP."
The power put on the state grid during peak demand periods in exchange for more power in off-peak periods is not broken down for each power plant, he said.
"It's a system-wide account," Strickland said. "There's no separate account for Hyatt alone."
However, he said there's a point at which water couldn't be released and power generation would cease.
Matt Notley, an information officer for DWR, said the lake level called "dead pool" is at 605 feet. Water levels dropped to 645 feet in 1977, but that's the lowest the lake has ever been.
Now, Notley said the lake is at 30 percent below storage capacity, and the lowest average lake elevations are 49 percent of full. Capacity is more than 3.5 million acre-feet.
The project transports water to about 20 million Californians and about 660,000 acres of irrigated farmland. About 70 percent goes to urban users and 30 percent goes to agricultural users.
The 29 water contractors repay all water supply related costs of the SWP.#
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