Greg Toppo, USA TODAY

and Redding (Calif.) Record Searchlight

Roads leading out of Oroville, Calif., were jammed with traffic Sunday evening some 140,000 people were ordered to evacuate the area due to the possibility of failure of the alternate spillway at Oroville Dam, authorities said.





Butte County Sheriff Kory Honea said during a news conference Sunday night that he had no choice but to order the evacuation.

“I didn’t have the luxury of waiting to see if all was OK. We need to get people moving quickly and to save lives in case the worst case came to fruition,” Honea said.

“This is a very dynamic situation. This is a situation that could change very, very rapidly,” he said.

“We recognize that this has caused a significant problem with traffic, in terms of exiting the area.”

State route 70 northbound, which runs past Oroville, was gridlocked as of 7:20 p.m. PT. Highway 99, an alternate north-south route eight 10 miles to the east, and state route 162 heading east, away from the Feather River, were jammed as were nearby surface streets, according to satellite feeds from Google Maps.

Highway 49 in Nevada County was turned into one-way traffic, according to Caltrans.

Oroville Police said its department arranged a medical evacuation for a man in a wheelchair in a house on Robinson Street, a few blocks from the Feather River, which runs below the endangered spillway.

Oroville residents were ordered to evacuate Sunday afternoon. The evacuation order was extended to include Marysville and Yuba County around 5:45 p.m. PT, according to Caltrans.

In a post on its Facebook page, the Butte County, Calif., Sheriff’s Department ordered an “immediate evacuation from the low levels of Oroville and areas downstream.”

Police said a “hazardous situation is developing” with the Oroville Dam auxiliary spillway, in which severe erosion could lead it to fail, resulting in an “uncontrolled release of flood waters from Lake Oroville.”

California Department of Water Resources officials had decided to use the emergency spillway to take pressure off the dam's regular spillway, which developed a giant crater last week, Redding (Calif.) Record Searchlight reported. That crater had been growing daily, so to take pressure off the spillway, the state began using the emergency spillway, but that also became compromised.

Flow through the broken main spillway was increased to 100,000 cubic feet per second in an effort to lower the water level in the lake more rapidly.

Residents of Oroville, located about 65 miles north of Sacramento, were ordered to evacuate northward, toward Chico, Calif. As of 6 p.m., Oroville police radio said there were "still a few stragglers" downtown but most people were gone. They also called for expanding the evacuation area to include area around the high school.

Honea wasn’t sure when residents would be able to return home. “We have to assess the safety of the spillway before we let the public back in,” Honea said.

Lake Oroville is one of California’s largest man-made lakes, and the 770-foot-tall Oroville Dam is the nation’s tallest. The lake is a central piece of California’s government-run water delivery network, supplying water for agriculture in the Central Valley and residents and businesses in Southern California.

The dam was built in 1968. Following heavy rains this winter, water on Saturday overtopped the emergency spillway for the first time since its completion, The Sacramento Bee reported Saturday.

Bill Croyle, acting director of the Department of Water Resources, said the dam itself is not threatened, but that the crisis won’t be over soon, since Northern California is on pace for its wettest winter ever. He said an estimated 2.8 million acre-feet of snow blankets mountains above the dam, putting more strain on it in months to come.

“Our next 60 to 90 days will be critical, how we route this (snow) runoff through this reservoir,” Croyle told The Bee. “There’s a lot of snow up there.”

In a tweet, the California Department of Water Resources late Sunday said it planned to use helicopters to drop rocks to fill in the gouge in the auxilliary spillway and stabilize it.

Michelle Grandinetti and her family quickly left their home, headed for family in Elk Grove, southeast of Sacramento.

“We took enough clothes for three days, our children, seven total that are still with us, our two dogs and food for them!” Grandinetti wrote in a Facebook message to The Bee. “We just moved here a few months ago and haven't ever had to deal with this! Everyone is leaving! All the stores are closed! Just got on the freeway and the river is only feet away!”

Erin English of Linda, Calif., told the Record Searchlight she got a robo-call telling her to evacuate and get to higher ground. She immediately called 911 and dispatchers at first told her to go to Chico, then said she might not make it there before water came through. They told her to go to Colusa Casino, about an hour's drive west.

She headed out with her husband, two children and her dogs. They didn't have time to grab anything from home, she said.

"I'm scared to death. I've never been through anything like this before. I pray for the safety of everybody here."

Kevin Carroll of Marysville, Calif., said he was dubious about the evacuation order, but he obeyed it. He and his wife gathered up clothes and their dogs and left. "My wife said go," he said. "The river is right on our back door."

But he said he didn't expect Marysville to flood. "I'm not saying it won't. There's a lot of room in that river right now," he said.

"It can save lives or be a waste of time. I hope for the best for the evacuees. Be safe."

Two tribal casinos in Oroville were trying to calm customers as they dealt with evacuation orders, and employees who picked up the phone had little time to talk.

“We’re really rushed right now,” said an employee at Feather Falls Casino & Lodge, about five miles south of the Feather River. “We’ve got the evacuation orders.”

At Gold Country Casino and Hotel, an operator said the phones “have been ringing off the hook” because of the emergency evacuations. That casino sits about three miles east of the river.

Kirsten McFaul, a student at Butte College and an Oroville native, said she drove to Sacramento when the college canceled classes on Friday. Yesterday, residents learned that the dam was at capacity and had overflowed into the spillway.

McFaul had been planning to drive home Sunday, but after the evacuation was announced her family left immediately and drove to Paradise, a town about 20 miles north of Oroville. They’re waiting there until it’s safe to return.

“We have been in fear of flooding since Friday, when we were told to prepare for evacuations just in case,” she said via Twitter. “We’ve had some (evacuations) uphill for fires but it was never a huge deal. We’ve never been evacuated like this in my lifetime.”

Contributing: Doug Stanglin, USA TODAY, and The Associated Press. Follow Greg Toppo on Twitter: @gtoppo