Oroville Dam: Residents remain in shelters as officials rush to repair damage before next storm hits
Updated
Tens of thousands of California residents remain in shelters as engineers work to shore up the tallest dam in the US before new storms sweep the region.
Key points:
- More storms are expected for Wednesday and Thursday this week
- Officials say the immediate danger of a wall of water sweeping through the area has been averted
- While safety is being reviewed, many residents remain in shelters that are running short on supplies
Authorities ordered mass evacuations on Sunday (local time) for 188,000 people living below the Lake Oroville Dam, out of concern a crumbling emergency spillway could fail and send a 10-metre wall of water roaring downstream.
That immediate danger has been averted, however, some evacuation orders remain in effect while the risk to those living in the Feather River Valley below the lake is being reviewed.
"We're doing everything we can to get this dam in shape [so] that they can return and live safely without fear. It's very difficult," California Governor Jerry Brown said.
Mr Brown sent a letter to President Donald Trump on Monday requesting he issue an emergency declaration, which would open up federal assistance for the affected communities.
The water level in the lake rose significantly in recent weeks after storms dumped rain and snow across California, particularly in northern parts of the state.
The high water forced the use of the dam's emergency spillway, or overflow, for the first time in the dam's nearly 50-year history on Saturday.
Crews dropped large bags filled with rocks into a gap at the top of the emergency spillway to rebuild the eroded hillside.
The main spillway, a separate channel, is also damaged because part of its concrete lining fell apart last week. Both spillways are to the side of the dam itself, which has not been compromised, engineers said.
The situation grew less dire as water levels dropped, leaving the weakened unpaved emergency spillway largely intact. By Monday, the level of the lake fell enough so that water was no longer pouring over the hill.
'I'm trying to get out of here too. That's a lot of water'
The sudden evacuation panicked residents, who scrambled to get their belongings into cars and then grew angry as they sat in bumper-to-bumper traffic hours after the order was given.
Raj Gill, managing a Shell station where anxious motorists got gas and snacks, said his boss told him to close the station and flee himself, but he stayed open to feed a steady line of customers.
"You can't even move. I'm trying to get out of here too. I'm worried about the flooding. I've seen the pictures — that's a lot of water," he said.
A Red Cross spokeswoman said more than 500 people showed up at an evacuation centre in Chico, California.
The shelter ran out of blankets and cots, and a tractor-trailer with 1,000 more cots was stuck in the gridlock of traffic fleeing the potential flooding on Sunday night, Red Cross shelter manager Pam Deditch said.
A California Highway Patrol spokesman said two planes would fly on Monday to help with traffic control and possible search-and-rescue missions.
At least 250 California law enforcement officers were posted near the dam and along evacuation routes to manage the exodus and ensure evacuated towns did not become targets for looting or other criminal activity.
All 23,000 California National Guard servicemen on standby
Department engineer and spokesman Kevin Dossey told the Sacramento Bee the emergency spillway was rated to handle 7,000 cubic metres per second, but it began to show weakness on Sunday after flows peaked at 350 metres per second.
The California National Guard notified all its 23,000 soldiers and airmen to be ready to deploy, the first time an alert for the entire Guard had been issued since the 1992 riots in Los Angeles.
The sudden decision on Sunday to evacuate tens of thousands of people was a departure from earlier assurances, when officials had stressed the Oroville Dam itself was structurally sound.
Officials are most concerned about the dam's emergency, earthen spillway, which began taking on water diverted from the main concrete spillway — but engineers do not know what caused it to cave in.
Chris Orrock, a Department of Water Resources spokesman, said it appeared the dam's main spillway had stopped crumbling even though it was being used for water releases through channels to route the water away from populated areas.
The aim is to lower the reservoir's overall water level by 15 metres — and prevent further spillover down the emergency hillside channel — before more rain arrives in the coming days and snow-melt runoff begins in the spring, acting state water resources director Bill Croyle said. He said he hoped to achieve that goal within two weeks.
Another storm was forecast to arrive as early as Wednesday or Thursday, though officials said they expected much of that precipitation to fall as snow rather than rain.
The lake is a central piece of California's government-run water delivery network, supplying water for the state's Central Valley agricultural heartland and homes and businesses in Southern California.
AP/Reuters
Topics: dams-and-reservoirs, floods, emergency-incidents, united-states
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