After two years of setbacks and struggles due to a severe drought, California got some good water news on Tuesday.
The reservoir behind the tallest dam in the state and the nation, Lake Oroville in Butte County, now has enough water in it after heavy December rains that the power plant began operation again.
The power plant was shut down on Aug. 5 because there was no longer enough water to spin the hydroelectric turbines and generate electricity. It was the first time for such a shutdown since 1967 when construction at Oroville Dam was completed, and the action became a symbol of California’s worsening drought.
Since then, however, the reservoir’s level has risen 76 feet, due to a powerful atmospheric river storm in October and a series of drenching storms in December.
“This is a significant milestone as California sees some relief from drought conditions,” said Karla Nemeth, director of the state Department of Water Resources. “Providing clean hydropower to the state energy grid allows DWR to assist in meeting the state’s clean energy goals.”
Lake Oroville is a massive reservoir which stretches 10 miles long when full. The linchpin of the State Water Project, it was constructed by former Gov. Edmund “Pat” Brown.
In August, following the driest two-year period in Northern California since 1975-77, Lake Oroville was just 24% full, reaching an all-time low. The water level sat well below boat ramps and images of the lake were broadcast by international news outlets.
As the state continued to make minimal water releases from the dam to stop the Feather River downstream from drying up — a requirement under federal and state law to protect fish and wildlife — the reservoir continued to drop.
It reached a low point on Sept. 30 at just 22% full.
After the rains of October and December, the reservoir has risen steadily. On Tuesday was 39% full.
While that represents a dramatic increase in the past three months — up 89 feet from its lowest point three months ago — the water level has another 183 feet to rise before the lake is full. And it’s still not yet back to normal for this time of year.
At 39% full Tuesday, it was 74% of its historic average for that date.
In August, the water level had fallen below the intake pipes that normally send water to spin six huge turbines at the Edward Hyatt Power Plant in the bedrock under the dam.
Hydroelectricity is the state’s second-largest source of power, providing about 15% of California’s electricity each year.
The loss of Oroville’s electricity didn’t cause blackouts. Even when the lake is full, the Hyatt power plant, one of the largest hydroelectric plants in the state, provides about 1% of California’s peak statewide electricity demand.
But the fact that Oroville Dam, a 770-foot tall colossus, could no longer generate electricity was an alarming reminder of the severity of the state’s drought.
State water officials said Tuesday that they have brought one of the turbines back into operation, generating 30 megawatts of power, and plan to bring others online as the lake level continues to rise.