Traffic during Oroville evacuation a worry for many | TheUnion.com

Traffic during Oroville evacuation a worry for many

Jake Abbott
Special to The Union

Editor's Note: Aided by respondents to an informal survey the Marysville Appeal-Democrat conducted earlier this year, the newspaper has compiled a list of concerns and questions about the Oroville Dam, the emergency there in February, the evacuations, etc. In this series, officials respond to those questions.

There were many takeaways from last February's Lake Oroville spillway incident, but one very alarming one: a large number of Yuba-Sutter residents who evacuated said they experienced issues with leaving the area, mainly due to traffic congestion. And a startling number of residents reported that they stayed home instead of fleeing, risking their lives in the event the emergency spillway did collapse.

Local officials were asked to recount the experience and to weigh in on the events of that day when nearly 180,000 residents from Butte, Sutter and Yuba counties packed up and headed for safety following the announcement that there was a chance a wall of water more than 30 feet high was headed downstream.

Question: About the evacuation and ways to improve the process: In an informal survey conducted by the Appeal-Democrat, 22 percent of respondents said they stayed at home and chose not to evacuate.

Answer: Yuba County Public Information Officer Russ Brown said the only time public safety officials order a mandatory evacuation is when the community is facing a potential life-or-death situation.

"Had the spillway collapsed, those residents would have had limited time to get out of an area that was projected to be inundated with more than 30 feet of water," Brown said.

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Brown said 60,000 residents were notified of the evacuation in Yuba County. Emergency responders really only have the ability to assist residents that are experiencing medical situations or need special assistance in the event of a catastrophe, so essentially it comes down to personal responsibility of the individual to heed the evacuation order when it is issued, he said.

"Yuba County Office of Emergency Services hopes all residents will be immediately responsive to evacuation orders, understanding that those orders were issued in sincere response to a dangerous situation," Brown said.

Chuck Smith, Sutter County public information officer, said the county conducted two online surveys this year asking residents similar questions about the spillway incident and found that 70 percent or more residents said they complied with the evacuation order.

Smith said there are a number of reasons some residents chose to stay behind. Some didn't have transportation or the financial resources; some weren't aware there was an evacuation; some might not have believed the threat was real and others just didn't want to or couldn't contend with the traffic, he said.

"Those who did not evacuate, and those whose experience it was that took more than eight hours to reach a safe place, could have drowned or been injured or might have had to be rescued had the spillway actually failed," Smith said.

He said local government agencies must work to improve outreach to local residents about preparedness in an emergency situation.

"They also must ensure there are multiple ways to communicate the risk to the public, including old and new technology," Smith said. "And they must work to be sure messages are clear, not contradictory, with actionable information."

Q: What could be done about the congested roadways out of the area and the bumper-to-bumper, stop-and-go traffic?

A: It's no secret that traffic was one of the biggest issues regarding the evacuation. Brown said public safety officials understand residents were frustrated about the bumper-to-bumper hold-up on virtually every major roadway out of the area.

"There are simply not enough evacuation routes to handle the number of vehicles evacuating," he said.

However, it didn't go as badly as some might suggest when considering the bigger picture, Smith said. First of all, it was a no-notice evacuation, meaning officials had no opportunity to strategically place resources in areas to help with the flow of traffic – all they were told was to get people out within the hour. Secondly, it was the single largest peacetime evacuation in U.S. history for anything other than a hurricane, Smith said.

"From the perspective of Yuba County OES, the traffic congestion was expected, and we believe the overall plan was successful to the point that all who evacuated were able to get to safety," he said. "The greatest danger came from those who chose to drive carelessly and endanger others."

As the area's population continues to increase, and the way people communicate evolves, it's important that local government agencies continue to push for improving highway infrastructure in the region, as well as "robust emergency management training" for county staff, Smith said.

"Sutter County, Yuba City and Live Oak will be conducting joint emergency trainings and all are committed to improving lines of communication, not only between the agencies, but with the operators of dams which impact this region," Smith said. "Not just Oroville, but also Bullards Bar and Shasta."

Officials encourage residents to check out county websites for more information on how to be prepared and other emergency planning information. Information for Yuba County residents can be found at http://www.BePreparedYuba.org. Sutter County residents can go to http://www.BePreparedSutter.org.

Q: Is the Lake Oroville Dam safe? A number of local residents have raised concerns over the safety of the dam itself. Despite questions of whether or not it is 100 percent safe from failure or if the structure has a life expectancy, officials from the Department of Water Resources say it is structurally sound.

A: "Oroville Dam was designed and constructed to meet the need for public safety with robust and resilient elements to control seepage, safely pass the largest of floods, and to be stable during high water events and seismic activity," said Erin Mellon, assistant director of Public Affairs for DWR.

The dam was founded on solid rock, she said. The rock foundation was reinforced with concrete, and the central, sloping core is supported by a concrete footing. Both the dam and its foundation have seepage collection and monitoring systems – a near vertical drain and a toe seepage weir.

When looking at the numbers, the dam has actually exceeded expectations – in terms of seepage and displacement – of what was anticipated during the initial design phase.

"The original design planned for up to five feet of post-construction crest settlement, but only about 10 inches has actually occurred," Mellon said. "Between seven and 7,000 gallons per minute of embankment seepage was estimated during design, but measurements show seepage of only about seven to 10 gallons per minute, which is very low for an earthen dam of its size."

Mellon said earthen dams typically don't have a set life expectancy because they allow for ongoing maintenance. The dam is periodically reviewed and evaluated, she said, to make sure it continues to meet dam safety standards – including annual inspections, performance reviews for monitoring instrumentation, as well as updates to hydrology and seismic stability.

State and federal law also requires the dam be reviewed every five years by an independent entity consisting of experts. Officials from the California Division of Safety of Dams and the Federal Energy Regulatory Commission conduct annual inspections too.

"Oroville dam remains safe and sound," Mellon said.

Mellon said even though the dam is structurally sound, downstream residents "should always be aware of their risk."

DWR developed an inundation map that shows what would happen in the event the dam itself failed, including estimates on how long it would take for water to reach certain areas and how deep it would be.

The map can be found here: https://goo.gl/jbcZEu.

Jake Abbott is a reporter for the Marysville Appeal-Democrat. Contact him at jabbott@appealdemocrat.com

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