At 8 a.m. Saturday, a sheet of water began spilling from the brim of California’s second-largest reservoir and washing down a partly cleared hill to the Feather River.
It was the first time in the 48-year history of Lake Oroville that the reservoir was so full that it triggered uncontrolled releases down an emergency spillway.
Bloated with storm runoff, the reservoir had gone from 80% full to overflowing in less than a week when managers were forced to reduce releases on Oroville’s heavily damaged concrete spillway.
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The emergency spillway was doing what it was supposed to do: letting water out of the huge lake so it wouldn’t top the dam.
State water officials called the spill a small one and said they expected it to end Sunday or Monday as lake levels dropped below the emergency threshold.
“The flow rates that we see now pose no threat to the dam and no flood threat to downstream waters,” said Bill Croyle, acting director of the state Department of Water Resources.
But he made it clear that while this is Oroville’s first emergency spill, it may not be the last.
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An aerial view of the water flowing out of the Oroville Dam main spillway, in Oroville, Calif., on Tuesday, February 21, 2017.
(Marcus Yam / Los Angeles Times)
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An aerial view of the water flowing out of the Oroville Dam’s main spillway on Feb. 21. (Marcus Yam / Los Angeles Times)
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Reduced water releases at the Oroville Dam have made damage to its main spillway more visible. (Marcus Yam / Los Angeles Times)
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With a reduced flow on Sunday, most of the water being released from the Oroville Dam is not going down the spillway; it has broken through and is flowing down the hillside. (Marcus Yam / Los Angeles Times)
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With a reduced flow on Sunday, most of the water being released from the Oroville Dam is not going down the spillway, it’s broken through and is going down the hillside.
(Marcus Yam / Los Angeles Times)
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With a reduced flow on Sunday, most of the water being released from the Oroville Dam is not going down the spillway, it’s broken through and is going down the hillside.
(Marcus Yam / Los Angeles Times)
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Juan Alvarez reassures his girlfriend, Sarah Hendrix, after helping her move out of her home in rural Maxwell. Water was a foot high and crews had to evacuate 100 people because of flooding-- some by boat.
(Marcus Yam / Los Angeles Times)
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Ron Chambers lets Duke out of his crate for the first time in hours since the flooding began n Maxwell, Calif. on Saturday.
(Marcus Yam / Los Angeles Times)
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Kevin Anfinson and other volunteers help shovel the muddy sediment that has built up in the salmon raceway at the Feather River Fish Hatchery in Oroville, Calif. (Marcus Yam / Los Angeles Times)
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Fernando Martinez and his mother, not pictured, wade through a road in Gridley, Calif., flooded by the Feather River as it continues to swell from the water being let out of Lake Oroville.
(Marcus Yam / Los Angeles Times)
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A man in a 4x4 truck turns around on Gridley Road after having second thoughts about making it across the flooded road, which had been closed.
(Brian van der Brug / Los Angeles Times)
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Randy Boheim packs up his tools and emergency supplies in anticipation of having to evacuate his whole family as floodwaters creep closer to his home in an Oroville, Calif., mobile home park. The nearby Feather River continued to swell from the water being let out of Lake Oroville ahead of this weekend’s storm.
(Marcus Yam / Los Angeles Times)
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A plantation in Oroville, Calif., sits in floodwaters as the Feather River continues to swell from the water being let out of Lake Oroville ahead of this weekend’s storm.
(Marcus Yam / Los Angeles Times)
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Helicopters ferry sand and rocks to the Oroville Dam’s emergency spillway reconstruction project in Oroville, Calif., ahead of coming rains.
(Brian van der Brug / Los Angeles Times)
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California Water Service district manager Toni Ruggle surveys the Feather River at Bedrock Park downstream from the Oroville Dam.
(Brian van der Brug / Los Angeles Times)
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McKenna Harvey, 9, left, Kylie Atteberry, 11, and Brooklyn Atteberry, 7, hold signs thanking workers in the repair effort at the Oroville Dam.
(Brian van der Brug / Los Angeles Times)
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A helicopter flies over as water flows from the main spillway at Lake Oroville. (Marcus Yam / Los Angeles Times)
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Reconstruction continues in a race to shore up the emergency spillway at Oroville Dam. (Brian van der Brug / Los Angeles Times)
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As rain clouds gather, friends from left, Johnny Eroh, Cody Balmer, Kristien Bravo and Jerel Bruhn hang out by the flooded Feather river in the Bedrock neighborhood of Oroville, Calif., last week. (Marcus Yam / Los Angeles Times)
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Evacuees at the Bangor Community Hall in Bangor, Calif., listen to Butte County sheriff’s deputies in February as the mandatory evacuation order was lifted. An evacuation advisory was lifted Wednesday. (Brian van der Brug / Los Angeles Times)
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Evacuees at the Bangor Community Hall get the news from Butte County sheriff’s Deputy Jeff Heath that the evacuation order has been lifted.
(Brian van der Brug / Los Angeles Times)
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Evacuee Sharon Dalton, right, hugs Raiden Ellis, 10 months, and Chris Ellis as they say their goodbyes as she leaves the Bangor Community Hall in Bangor, Calif., on Tuesday.
(Brian van der Brug / Los Angeles Times)
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David McGlamery returns to his Oroville home with his belongings after the evacuation order was lifted. The family had to retreat to Chico, where they initially stayed at a Walmart parking lot with other evacuees. (Marcus Yam / Los Angeles Times)
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Bill Tirey helps family members move back into their home in the Bedrock neighborhood of Oroville near the Feather River after evacuation orders were lifted.
(Marcus Yam / Los Angeles Times)
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Maria Alancar returns home to greets her pet pig Bacon, who was left behind when the family moved to higher ground in Honcut, Calif.
(Brian van der Brug / Los Angeles Times)
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Sulet Lopez, 21, left, Melissa Mendoza, 3, and Yeanet Lopez, 18, pack up their car at the Bangor Community Hall in Bangor, Calif., to head home after the evacuation order was lifted.
(Brian van der Brug / Los Angeles Times)
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Erica Stenholm, left, Ronnie Vaughan, and Brooklyn Jackson, 7, unpack their car upon returning home after the evacuation order had been lifted in Oroville.
(Marcus Yam / Los Angeles Times)
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Jonah Avina, left, and his wife, Eileen, pray before lunch at the Maranatha Mennonite Fellowship in Bangor, Calif., on Tuesday. The Bangor-area Mennonites are hosting several immigrant families evacuated from the nearby town of Honcut.
(Brian van der Brug / Los Angeles Times)
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Evacuee Estafani Reynoso, left, colors with Mennonite children at the Maranatha Mennonite Fellowship in Bangor, Calif.
(Brian van der Brug / Los Angeles Times)
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Crews work on a damaged section of the emergency spillway at Lake Oroville on Monday. (Josh Edelson / AFP/ Getty Images)
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An Oroville property is flooded on Monday as thousands were under evactuation orders.
(Josh Edelson / AFP/Getty Images)
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The Marysville cemetery underwater along the Feather River.
(Marcus Yam / Los Angeles Times)
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Nirmal Singh, a Sikh priest, conducts a morning prayer ritual as evacuees sleep in the background at the Shri Guru Ravidass, a Sikh temple that has opened its doors for evacuees of the Oroville Dam crisis in Rio Linda, Calif.
(Marcus Yam / Los Angeles Times)
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Kamlesh Nahar, far left, talks to fellow evacuees at the Shri Guru Ravidass Temple.
(Marcus Yam / Los Angeles Times)
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Maria Lopez reads on her smartphone as she spends a second night in her father’s car in the parking lot of the Bangor Community Hall.
(Brian van der Brug / Los Angeles Times)
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Sharon Dalton finds a quiet spot under a table as she spends a second night with her dog Cruiser inside the Bangor Community Hall.
(Brian van der Brug / Los Angeles Times)
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Verna Chadwick and 10-month-old son Raiden Ellis during a second night in the Bangor Community Hall.
(Brian van der Brug / Los Angeles Times)
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The emergency spillway, left, and the damaged main spillway at Lake Oroville are seen in an aerial photo Monday.
(Elijah Nouvelage / Getty Images)
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A dump truck crosses the primary spillway to deliver boulders to the damaged emergency spillway at Lake Oroville on Monday evening.
(Brian van der Brug / Los Angeles Times)
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Helicopters place large rocks on the damaged emergency spillway at Lake Oroville on Monday evening.
(Brian van der Brug / Los Angeles Times)
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Around-the-clock monitoring continues on the damaged primary spillway at Lake Oroville on Monday evening.
(Brian van der Brug / Los Angeles Times)
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Water rushes down a spillway at the Oroville Dam. (Brian van der Brug / Los Angeles Times)
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California Department of Fish and Game wardens view the damaged spillway on Monday. (Brian van der Brug / Los Angeles Times)
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Bill O’Kelley, 86, and wife Doris O’Kelley, 84, of Oroville sit near a flagpole Monday at the Silver Dollar Fairgrounds evacuation center in Chico, Calif.
(Brian van der Brug / Los Angeles Times)
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Coua Tha, of Oroville prepares a meal for her family in the parking lot at the Silver Dollar Fairgrounds evacuation center in Chico, Calif.
(Brian van der Brug / Los Angeles Times)
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Desiree Garcia and daughter Kay’lee Pearl Garcia, 3, of Oroville look over donated clothing Monday at the Silver Dollar Fairgrounds evacuation center in Chico, Calif.
(Brian van der Brug / Los Angeles Times)
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Members of Oroville’s Jordan Crossing Mission pray with a volunteer service member Monday at the Silver Dollar Fairgrounds evacuation shelter in Chico, Calif.
(Brian van der Brug / Los Angeles Times)
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The swollen Feather River flows through Oroville, Calif., on Monday.
(Rich Pedroncelli / Associated Press)
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A building is submerged in Riverbend Park as more water is released from Lake Oroville.
(JOSH EDELSON / AFP)
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Siblings Zach Soto, 11, left, and Gabby Soto, 13, keep an eye on the Feather River along a railroad bridge in Oroville, Calif., on Monday. The family decided to stay in Oroville as they live on high ground near downtown.
(Brian van der Brug / Los Angeles Times)
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Water flows down the damaged main spillway of the Oroville Dam at 55,000 cubic feet per second into the Feather River. (Brian van der Brug / Los Angeles Times)
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Water from Lake Oroville flows down the damaged main spillway.
(Brian van der Brug / Los Angeles Times)
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Water from Lake Oroville flows down the emergency spillway of the Oroville Dam toward the Feather River.
(Brian van der Brug / Los Angeles Times)
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Pacific Gas & Electric crews aided by a helicopter removed transmission lines and insulators from towers standing in the bed of the emergency spillway of Lake Oroville.
(Brian van der Brug / Los Angeles Times)
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A rainbow appears over Feather River as water cascades down the damaged spillway at Lake Oroville Dam.
(Brian van der Brug / Los Angeles Times)
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Water cascades down the spillway below Oroville Dam. The water is being released by authorities to avoid flooding at Lake Oroville because of recent heavy rain. (David Butow / For The Times)
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Pacific Gas and Electric Co. crews move two electric transmission line towers on the bank of Feather River as a precaution if the Lake Oroville Dam emergency spillway needs to be used.
(Brian van der Brug / Los Angeles Times)
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A California Highway Patrol cruiser patrols Lake Oroville Dam, which is closed to the public due to the damaged spillway.
(Brian van der Brug / Los Angeles Times)
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Water cascades down the spillway below the Oroville dam. The water is being released by authorities to ease flooding in Lake Oroville because of recent heavy rain.
(David Butow / For the Times)
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Butte Country Sheriff Kory L. Honea speaks with department of water and power workers at an overlook as the observe runoff from the Oroville Dam.
(David Butow / For the Times)
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Water trickles down as workers inspect part of the Lake Oroville spillway failure in Oroville, Calif.
(Randy Pench / Associated Press)
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A boat launch at Bidwell Canyon is still hundreds of yards above the current lake level on Jan. 21, 2016.
(Brian van der Brug / Los Angeles Times)
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California State Park Ranger Bryan Taylor searches for signs of disturbance or theft as California’s severe drought conditions are revealing historic artifacts at Lake Oroville, June 21, 2014.
(Allen J. Schaben / Los Angeles Times)
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Severe drought conditions are evident as a family treks across a long path back to their car at Lake Oroville, June 21, 2014.
(Allen J. Schaben / Los Angeles Times)
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Houseboats are dwarfed by steep banks that show the water level down 160 feet from the high water mark at the Bidwell Bar Suspension Bridge over Lake Oroville on June 21, 2014.
(Allen J. Schaben / Los Angeles Times)
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Houseboats at Bidwell Canyon Marina at Lake Oroville, January 21, 2016.
(Brian van der Brug / Los Angeles Times)
With northern Sierra precipitation levels tracking ahead of the wettest year on record so far this winter, Oroville managers have a nerve-racking several months ahead of them. “There’s a lot of snow up there,” Croyle observed.
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The snowpack in the northern Sierra, which includes the Feather River watershed, is 150% of normal for the date. Statewide it is 180% of average.
Reservoirs around the state are making flood-control releases.
In Mariposa County, the small reservoir behind Mariposa Dam was overflowing, sending water down its spillway for the first time since the 1950s, said Merced County spokesman Mike North. About 25 homes were flooded Saturday by the swollen Mariposa Creek.
This winter’s turnaround from five parched years has been dramatic. A year ago at this time, Oroville was slightly less than half full. In 2014, it was a little more than a third full and its receding shoreline served as a vivid symbol of the drought’s punishing toll on the state.
But Californians shouldn’t be surprised.
“If you look at a map of the U.S. and weather variability, California is the most variable place in the country,” said Jeff Kightlinger, general manager of the Metropolitan Water District of Southern California. “This is an extreme. But it’s not outside of what we’ve experienced in the past.”
Completed during the administration of Gov. Ronald Reagan, Oroville is the keystone of the State Water Project that sends Northern California water hundreds of miles to the Southland.
As the head of the project’s biggest customer, Kightlinger has been anxiously watching since Tuesday, when a hole big enough to swallow a small house opened in the long concrete chute that is the lake’s normal spillway.
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Dam managers briefly shut down releases and then restarted them at a reduced rate as they struggled to keep the lake from rising to a point that would trip emergency spills.
Friday they thought they had managed to do that. But it rained Friday night. By Saturday morning the lake level had risen to an elevation of 901 feet — the point at which water started washing over the 1,700-foot-long top of the emergency spillway.
It snaked down the hill, a shallow rippling stream glinting in the sunlight.
Dam managers wanted to avoid that sight for two big reasons. They don’t control the emergency releases. Nature does. The spill won’t stop until inflow volumes drop below the discharge.
And as the water streams down the hillside, it carries sediment and debris into the Feather River — material that can clog the river channel, the dam’s powerhouse and downstream diversion facilities.
Crews worked frantically at the end of the week clearing trees and brush from the water’s emergency path. Utility crews used helicopters to remove power lines.
Booms and boats were brought in to collect debris from the pool at the dam’s base. More than 10 million salmon were evacuated from the Feather River hatchery downstream because the river water had grown too muddy for them.
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Water flows down a hillside from the emergency spillway at Lake Oroville depositing mud and debris into the Feather River in Oroville, Calif.
(Brian van der Brug / Los Angeles Times)
Engineers are limiting flows down the damaged spillway so as not to further erode it. But that is also cutting releases, which means that after this emergency spill is over, more may be necessary to counter runoff in future storms.
Croyle said the state is already studying repair options, including building a new spillway to replace the broken one. But that work can’t begin until the runoff season ends. And it will be expensive.
Croyle estimated that it will cost $100 million to $200 million to fix the spillway — a bill that will largely go to State Water Project contractors, including Metropolitan.
“Obviously down the road, we’ll be talking with FEMA and the federal government and the state government about disaster funds,” Kightlinger said. “But … there will eventually be a sizable bill for the state water contractors — and ultimately to Metropolitan.”
Kightlinger said his agency is volunteering technical and engineering assistance to the state to develop repair plans.
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He agreed that Oroville’s earthen dam “should be in fine shape.” But he said the unprecedented use of the emergency spillway comes with risks of hillside erosion and sending damaging sediment downstream.
“We just hope they make it through this winter without catastrophic damage and go from there,” Kightlinger added.
Greg and Doreen Schmidt live in a low-lying area of downtown Oroville, not far from the dam.
“Once it spills over” the emergency spillway, “who knows what’s going to happen,” Greg Schmidt said. “But it seems like they have it under control.”
Nonetheless, Doreen said, “I have my bags packed and I’m on alert.”
Ralph Thomas was more sanguine as he watched the roiling dam releases flow under the Table Mountain Boulevard Bridge in Oroville.
“This ain’t nothing compared to ’97,” he said. “Back then the water was almost up to the bridge.”
Bettina Boxall covered water and the environment for the Los Angeles Times before retiring in 2021 after 34 years at the paper. She shared the 2009 Pulitzer Prize for explanatory reporting with colleague Julie Cart for their five-part series on the causes and effects of escalating wildfire in the West.
Patrick McGreevy covered the California Legislature out of the Sacramento bureau until 2021. He joined the Los Angeles Times in 1998 and worked in the City Hall and San Fernando Valley bureaus, writing about subjects including Valley secession, LAPD reform and city government during the administrations of Mayors Richard Riordan, James Hahn and Antonio Villaraigosa. He is a native of San Diego and a graduate of San Jose State University.
