Four years ago, Oroville Dam, the tallest in the United States, made international news when its massive 10-mile-long reservoir filled to the top in heavy winter storms, and raging waters destroyed its spillway, causing the emergency evacuation of 188,000 people.
But now, in the latest symbol of California’s worsening drought, the opposite problem is underway: Lake Oroville’s water level has fallen so low that on Thursday, for the first time since the dam was built in 1967, its power plant was shut down because there is no longer enough water to spin the turbines and generate electricity.
“This is just one of many unprecedented impacts we are experiencing in California as a result of our climate-induced drought,” said Karla Nemeth, director of the state Department of Water Resources, which owns the dam.
On Thursday, the reservoir was only 24% full, having fallen below an all-time low record set in September 1977. The lake level has dropped a stunning 250 feet in the past two years. The water level has 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.
The loss of Oroville’s electricity won’t by itself 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 problem illustrates a wider challenge facing California this year from the drought. Reservoirs are low all over.
And hydroelectricity is the state’s second-largest source of power, providing about 15% of California’s electricity each year. During the first four months this year, hydroelectric production in California fell 37% compared with the same time last year and 71% compared with 2019, according to the U.S. Department of Energy.
That power has to be made up to reduce the risk of blackouts.
“This is a huge problem. It’s part of the big challenge we are facing this summer,” said Severin Borenstein, co-director of the Energy Institute at the Haas School of Business at UC Berkeley.
The lost electricity can be replaced largely by increasing natural gas power plant production and importing electricity from other states, said Borenstein, who also serves on the board of the California Independent System Operator, which runs the state’s power grid.
But as California increasingly moves to renewable energy to reduce climate change and air pollution, hydropower is more valuable than ever, he said. That’s because as the sun goes down in the evening during hot summer months, solar energy drops. But people in the Central Valley, Southern California and other areas where temperatures regularly exceed 100 degrees continue to run air conditioners to keep cool.
If there are heat waves across the West, other states don’t have much extra electricity to sell to California. Last year, during a record heat wave, the state experienced two blackouts, the first in 20 years.
Last Friday, hoping to avert any more power shutdowns, Gov. Gavin Newsom issued an emergency order that temporarily waives some air pollution rules to allow natural gas power plants to generate more electricity and pays industries $2 a kilowatt-hour to reduce their electricity use during heat waves.
Many experts say hotter heat waves, wildfires that can destroy power lines, and shrinking reservoirs will be a regular part of California’s future.
“We are in a new normal. The planning needs to accommodate that,” said Siva Gunda, a member of the California Energy Commission. “We’re not talking about climate change coming. It’s here.”
Gunda, a mechanical and aeronautical engineer who formerly worked as the research director at the UC Davis Energy Efficiency Institute, said he remains hopeful.
“I’m cautiously optimistic that we won’t have any blackouts this year,” he said. “We are working really hard to make sure we get through. But it’s going to be tight.”
The ultimate solution, Gunda and Borenstein said, is for the state to continue to work with private industry to build more battery facilities to store electricity from solar power during the day and release it on the grid when the sun goes down on hot nights. State regulators also are requiring utilities like PG&E to line up more contracts to provide electricity during extreme heat waves.
This summer, none of that will help Lake Oroville. Just two years ago, in June 2019 after a wet winter, the reservoir was 97% full.
But after the two-driest years since 1976-77, the state’s below-average winter snowpack didn’t melt and flow into reservoirs. Most of it simply soaked into the bone-dry Sierra ground. Now all but one of Oroville’s boat ramps are above the lake level. Environmentalists say the state should have planned better and not given so much water from Oroville and other reservoirs to senior water rights holders, like farmers in the Central Valley.
“This wasn’t just the result of drought,” said Doug Obegi, an attorney with the Natural Resources Defense Council in San Francisco. “It was the result of decisions to allocate unreasonable amounts of water despite the drought.”
John Yarbrough, assistant deputy director of the State Water Project, said planners at the state Department of Water Resources were shocked at how the snowpack runoff didn’t flow into reservoirs.
“This year was unique. We had lower than average snowpack,” he said. “And only 20% of it turned into runoff that went into the reservoirs. When people think of the impacts of climate change, that’s what we observed this year.”
