Reporting from Oroville, Calif. — More than 100,000 people in communities downstream of Lake Oroville were told to evacuate Sunday evening after authorities grew concerned that dangerous flood waters would start surging out of the huge reservoir.
The flood threat emerged suddenly Sunday afternoon when a hole developed in the auxiliary spillway that was being used for an emergency spill to lower the level of the full-to-the brim reservoir, the second-largest in California.
If the erosion advanced quickly uphill, it could undermine the concrete top of the spillway, allowing torrents of water to wash downhill into the Feather River and flood nearby Oroville and other downstream towns.
Kevin Lawson of CalFire said it had threatened to “unleash a 30-foot wall of water coming out of the lake.”
But by 10 p.m. Sunday, officials said the immediate threat had passed because water had stopped washing over the emergency spillway.
Nonetheless, the situation at the reservoir remained precarious. The two main avenues for getting water out of the lake — the unpaved emergency spillway and the main concrete spillway — were both damaged.
Both spillways are separate from Oroville Dam itself, which state officials continued to say was not in danger. The main spillway, a long concrete chute off to the side of the dam, has a gaping gash in it that forced officials to reduce releases last week.
That caused the lake to quickly rise with heavy storm runoff, triggering emergency releases down the auxiliary spillway, which consists of a concrete weir at the reservoir’s edge that sends flows down a hillside into the Feather River.
Although the emergency spill was small, it started to erode the hillside Sunday afternoon.
“There was significant concern that [the erosion] would compromise the integrity of the spillway, resulting in a substantial release of water,” Butte County Sheriff Kory Honea said at a Sunday evening news briefing.
“We had to make a very critical and difficult decision to initiate the evacuation of the Oroville area,” he added.
“Immediate evacuation from the low levels of Oroville and areas downstream is ordered,” proclaimed a Sheriff’s Department statement posted on social media. “This is NOT A Drill.”
The order affected rural communities located along the Feather River and included the counties of Butte, Yuba and Sutter. Oroville residents were told to make their way north of the lake to Chico, where an impromptu evacuation shelter had been set up at the fairgrounds.
The Yuba County Office of Emergency Services urged evacuees to travel only to the east, south or west. “DO NOT TRAVEL NORTH TOWARD OROVILLE,” the department said on Twitter.
As traffic slowed to a crawl, travelers reported encountering road blocks heading north on California highways 70 and 99. For those headed south, the driving was no easier as thousands poured onto the highways in an attempt to evacuate.
Belen Castaneda, 23, a preschool teacher from Biggs, fled her home around 4:30 p.m. for the Silver Dollar fairgrounds.
“We just grabbed everything we could,” she said. “Everyone was freaking out.”
Castaneda and her family — three sisters and her mom and dad — drove in two separate cars, bringing along their elderly neighbor who doesn’t speak English.
Castaneda said her family took special care to bring irreplaceable items. “Old family pictures we had brought from Mexico that we had for a long time,” Castaneda said, “and our birth certificates.”
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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California Water Service district manager Toni Ruggle surveys the Feather River at Bedrock Park downstream from the Oroville Dam.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Evacuee Estafani Reynoso, left, colors with Mennonite children at the Maranatha Mennonite Fellowship in Bangor, Calif.
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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.
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The Marysville cemetery underwater along the Feather River.
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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.
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Kamlesh Nahar, far left, talks to fellow evacuees at the Shri Guru Ravidass Temple.
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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.
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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.
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Verna Chadwick and 10-month-old son Raiden Ellis during a second night in the Bangor Community Hall.
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The emergency spillway, left, and the damaged main spillway at Lake Oroville are seen in an aerial photo Monday.
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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.
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Helicopters place large rocks on the damaged emergency spillway at Lake Oroville on Monday evening.
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Around-the-clock monitoring continues on the damaged primary spillway at Lake Oroville on Monday evening.
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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.
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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.
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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.
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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.
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The swollen Feather River flows through Oroville, Calif., on Monday.
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A building is submerged in Riverbend Park as more water is released from Lake Oroville.
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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.
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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.
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Water from Lake Oroville flows down the emergency spillway of the Oroville Dam toward the Feather River.
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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.
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A rainbow appears over Feather River as water cascades down the damaged spillway at Lake Oroville Dam.
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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.
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A California Highway Patrol cruiser patrols Lake Oroville Dam, which is closed to the public due to the damaged spillway.
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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.
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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.
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Water trickles down as workers inspect part of the Lake Oroville spillway failure in Oroville, Calif.
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A boat launch at Bidwell Canyon is still hundreds of yards above the current lake level on Jan. 21, 2016.
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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.
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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.
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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.
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Houseboats at Bidwell Canyon Marina at Lake Oroville, January 21, 2016.
(Brian van der Brug / Los Angeles Times) She also grabbed a couple items from her sprawling makeup collection.
“Some of that stuff is limited edition,” she explained.
By Sunday night, experts were planning to plug the crevice in the emergency spillway with bags of rocks dropped from helicopters.
They had also doubled discharges down the main spillway to help lower the lake level and reduce the overflow.
Lake Oroville is the keystone of the State Water Project that sends Northern California water hundreds of miles south to the southern San Joaquin Valley and the Southland.
In addition to flooding concerns, if operators can’t easily get water out of the lake that could interfere with deliveries to contractors, including the Metropolitan Water District of Southern California.
A series of powerful storms in Northern California sent runoff rushing into the lake just as a gaping hole developed in the main spillway Tuesday, forcing managers to reduce releases.
That pushed the reservoir to overflow Saturday, marking the first time the emergency spillway was used since the dam was finished in 1968. Until Sunday afternoon, it seemed to be going smoothly.
Millions of gallons of rushing water continued to pound and erode the massive Lake Oroville Dam spillway.
James Nash, 86, heard about the evacuation order from his apartment building manager. A retired chef and Korean War vet, he wasn’t sure where to go.
He couldn’t get to Chico on his bike. He had a small bag with shaving gear, a washcloth and paper towels. “No blankets. No water,” he said.
He remembered the 1997 evacuation order, which he ignored. There was no flooding then and he was pretty sure nothing would happen this time.
“I don’t believe it’s going to happen,” he said.
But he wasn’t comfortable enough to go back home, so he kept watching the water in the river below.
On Sunday evening, Christopher Cruz, 21, and his girlfriend, Jessica Isaacson, 18, waited outside of a CVS surrounded by the plastic jugs they had filled with water and the snacks and clothes they’d packed.
Stranded in Oroville, where they rent a room, they had hoped Isaacson’s mother would pick them up, but she was stuck in Chico. Finally, they called local law enforcement, who told them to wait outside the pharmacy until someone came for them.
Cruz said that when Lake Oroville started to hit its overflow point a few years earlier, he had thought about packing a bag.
“I just thought everything was going to blow over,” he said.
This time, with no car, he and Isaacson had set out walking, only to run into a police officer who told them in no uncertain terms that they were going in a dangerous direction.
“Heading that way is heading for death,” he told them.
bettina.boxall@latimes.com | chris.megerian@latimes.com | paige.stjohn@latimes.com | melanie.mason@latimes.com
Times staff writers Anna Phillips and Matt Hamilton contributed to this report.
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